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# OAR Box 1877 Prepped by Keeia Richards



## Document

Number: 

# 43 ) ll-B-4 0 Docket Number: 

# A-90-1 9

Primed 12/2/200810:36:50AM

Sheet 43 of 46* I 

## P. 2 

# A-90-1 9 ll-B-4 0 MEMORANDU M TO : Proces s Vent s Docke t A-90-1 9 FROM : Wand a Floy d DATE : Decembe r 199 0 SUBJECT : HO

NNESHAP : IndustryCharacteristics/Cresol s Attache d i s a product-proces s summar y(PPS ) fo r th e productio n o f Cresols/Cresyli c Acid s (Mix ) vi a Recover yfro mSpen t Refiner yCaustic s category . Thi s PP S wa s develope d a s par t o f the Industria l Profil e projec t i n suppor t o f the Hazardou s Organi c NESHA P (HON ) regulator yeffort . Informatio n i n thi s PP S i s use d a s a basi s fo r emission s an d cos t impac t estimate s fo r th e HONprogram . Liste d belo w ar e the keyreference s use d i n developin g the attache d PPS . Genhartz , Wolfgang , ed . Ullmann' s Encyclopedi a o f Industria l Chemistry . 5t h edition . VC H Publishers , Florida , 1985 . pp . 25-47 . "Cresylics. " In : Chemica l Marketin g Reporter . Schnel l Publishin g Company , Ne w York , Novembe r 30 , 1987 . "Cresol s & Cresyli c Acid. " In : Mannsvill e Chemica l Products . Ne w York , Novembe r 1985 . 198 9 Directoryo f Chemica l Producer s USA . SR I International , California , p . 542 . McKetta , Joh n J. , ed . Encyclopedi a o f Chemica l Processin g and Design , Marce l Dekker , Inc. , NewYork , 1977 . pp . 212-225 . Kirk-Othmer . Concis e Encyclopedi a o f Chemica l Technology . Joh n Wile y& Sons , Ne w York , 1985 . p . 73 . Shreve , R . Norri s and Brink , Jr. , Josep h A . Chemica l Proces s Industries . 4t h edition . McGraw-Hil l Boo k Company , NewYork , 1977 . pp . 72-77 . Kirk-Othmer . Encyclopedi a o f Chemica l Technology . 3r d edition . Joh n Wile y6 c Sons , Ne w York , 1978 . Volum e 22 . p . 593 . 

# 00:0*. A-90-1 9

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## Date : f/io/to Reviewer : ADMINISTRATIV E NOTE S 

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### 3 0 Cresol s an d Xylenol s wil l be expande da s th e price s o f oil andnatura l ga s rise . Thi s woul dyiel

dmore low-temperature tar , i n whic h th e conten t

of cresol s an dxylenol s i s much greate r

tha n i n high-temperatur e coke

ove n tar . 1.3.2 . Recover

y fro m SpentRefiner

y Caustic s I n th e Unite dStates , cresol s an dxylenol s are obtaine dmainly fro

mth e naphth afraction s pro duce db y catalyti c an dtherma

l crackin g i

n the petroleu mindustry , whic

h contain , o n th e aver age , ca . 0. 1 % C 6 -C 8 phenol s [34] , [36] . I n th e scrubbin g of

th e sulfu r compound s containe di

n thes e fraction s (hydrogensulfides , alkyl

- an d arylthiols ) wit

h concentrate dalkalin e solutions , aproces s know n a s "sweetening, " th e aci d cresol s an dxylenol s are als o extracted . Th e com positio n of

th e spent cresylat e caustic s fluctuates widely , an dthe

y contai n o n th e averag e 20-25 % C 6 -C 8 phenol s an d10-15 % sulfu r compounds . Th e caustic s are collecte db y th e re processin g firms Merichem , Northwes t Petro

chemical , andProductol , an dare reprocesse di n central plant s b

y avariet y o f processes . A t the Northwes t

Petrochemica

l i n Ana

cortes , Washington , th e thiol s i n th e alkalin e solutio n ar e first

oxidize dwit

h air t o giv e disul

fides, whic

h ar e then decante da s a

n oil y laye r [37] : RSN a + R'SN a + 0. 5 O , + 11, 0 . RSSR

: + 2 NaO l I Th e phenol s ar e then precipitate dfro mth e aqueou s alkalin e phas e i

n apacke dcolum

n wit h acountercurren t

strea mof carbo n dioxid e (flu

e gas ) an ddecanted . Th e phenol s still present i n the carbonate-hydroge n carbonat e phas e (2

- 6% ) are extracte dwit

h a n organi c solvent , fro

m whic h the y are extracte dagai n wit

h a n aqueou s alkalin e phase , whic

h i s then returne dto th e col

umn . A typica

l compositio n o

f th e pheno l mix

ture obtaine di

n thi s wa y migh t b e a s follows : 20 % phenol , 18 % o-cresol , 22 % w-cresol , 9 % p-cresol , 2 8 % xyleno l (all si x isomer s plu s ethyl

phenol) , an d3 % highe

r phenols . Thi s mixture i s then separate db

y distillatio n int o phenol , ocresol , m-/p-creso\ mixture , an dxylenols , o r mix

ture s in whic

h particula

r constituent s predomi

nate . Th e Meriche

mCo . of Houston , Texas , i s the bigges t processo r of spent refiner y caustics , in th e Unite dStates , an dprecipitate s th e phenol s wit h Vol . A 8 hydroge n sulfide , awast

e produc to f th e refinerie s i n Houston [38] , [39] , instea d o f usin g carbo n dioxide . Afte

r extraction wit

h asolvent

, th e sulfid e solutio n obtained in thi s process is concentrate

d i n a triple-effec

tevaporator t

o giv e sodiu msulfid

e fo r us e in th e pape r

industr y an d i n ore dressin g [39] . Th e water vapo r condensat e forme dat

thi s stag e i s strippe d wit

h natura l ga s t o remov e odo

rou s compounds , afte

r whic h i t i s passe dt o a coolin g tower . Th e natura l ga s i s then useda s a fue l i n th e final proces s ai r

incinerator . Befor

e being introduce dint o the wast e ai r incinerator , whic h i s operate da t

ca . 1370°C , th e proces s ai r fro mall of th e othe r

part s of th e plan t

i s scrubbe dwit

h alkalin e solution . In addition , odor-neutralizin g chemical s ar e spraye dalong

sid e th e plan t

area . Al l of th e water at th e plan t (includin g rai n water) i s recycledi n a n integrate d system . Water

i s release dint o th e environment almos t completely a s water

vapo r fro mth e cool

ing tower s [39] , [40] . Accordin g to the proces s operated unti l 197 1 b y the Pittsburg h Consolidate d Chemica

l Co . [41] , [42] , the spen

t refiner y caustic s wereireate d directl y wit h flu e ga s contain in g 8-14 % carbo

n dioxide.'Fro m the crude pheno l thu s precipitated , a fraction boilin g a t100-23 5 " C was remove d b y distillatio n an

d extracte

d continuousl y in a counter curren to f aqueou s methanol-ligh tnaphtha . Afte r remova l o f the fina l thiol an d base residues wit

h a n ion exchange resin , the cresylic acid s tha tha d entere d th e aqueous methanoli c phase wer e recovere

d b y fractiona

l distillation . I n 1984 , the "cresylics " capacitie s of Meri

chem , Northwest , an dProducto l wer e 5 5 000 , 15000 , an d1000 0 t/a , respectivel y [43] . Howev

er , thes e figure s include phenol , th e xylenols , an d severa l othe r alkylphenols . I

n addition , Meri

che mn o longe

r isolate s cresylic s exclusivel y fro mspent refiner y caustics , bu t

als o work s u

p crud e phenol s fro

mcoa l tar s of variou s types . Th e recover

y of cresol s an dxylenol s fro

m spen t refiner y caustic s ha s s o fa

r bee n confine d t o th e Unite dStates . Becaus e differen t refiner y technique s ar e usedin th e Federal Republi c of Germany , the ' productio n o f cresol-containin g spent caustic s i s insufficien

t fo r economica

l re processing ; o r

n o spent caustic s are produce da t all becaus e desulfurizatio n i s carrie dou t differ

ently , e.g. , b

y hydrotreating . I n th e Unite dState s a s well , th e recover

y of creso l fro mspent refiner y caustic s i s stagnatin g o r

eve n recedin g becaus e the refinerie s ar e likewis e changin g ove r either to hydrotreatin g o r

t o UOP' s Mero x process , partl y becaus e th e pric e of

sodiumhydroxide ha s risenP.1 1



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# SH-37 7

fourth edition 

# CHEMICA

L PROCES S INDUSTRIE S

R . NORM S SHREV E Lau ProfossorEmaritus of Chtmicat

Engin—ring Purdttt Vnivttrsity 

### JOSEP H A . BRINK , JR . Consulting Chtmicat

Enginmmr Professorand

Chairman of

Oumieal Engimaring Washington Stat* Vnivtnitr

MeCRAW-HIL

L BOO KCOMPAN

Y Horn IW * Ss. Lornls San Francisco Atddmmd Bog—. OtsssUorf

Johamasburg Undo* Madrid Main Motmal >« r Dolhl

Panama Paris _<_

_Pamlm Singapore SydnarTokyo Toromsa 

# mm

LIBRAR Y DURHAM , N.C.Librar y o f Congrea a Catalogin g i a PabUeatio a Dat a Shreve , Randolp

h Norris , 1885-1975 . Oiemica l proces s industriea . Include s bibliographie s an dindex . 1 . Chemistry , Technical . I . Brink , Joseph A. , date , join t author . II . Tide . TP14S.S 5 197 7 660. 2 77-423 6 ISB N 007^57145- 7

Copyrigh t © 1977 , 1967 , 195 6 b

y McGraw-Hill , Inc . All rigfat s reserved . Copyrigh t 194 6 b y McGraw-Hill , Inc . All right s reserved . Printe di n th e UnitedState s o

f America . N

o par t o f thi s publicatio n ma

y b e reproduced , store di

n aretrieva

l system , or transmitted , i

n an y for mor b y an y means , electronic , mechanical , photocopying , recording , o r otherwise , withou

t th e prio r writte n permissio n o

f di e publisher . 3456789 0 FGRFG R786543210 9

The editon for

this book

vert Jeremy Robinion and

Either Gelalt, and the production supervisor was Teresa F. Leaden. It vas set in Bodoni Book. Printed and bound by Fairfield

Graphics.



## •tf7 2 [Chap. 5] Coal Chemicals ammoni a liquo r i s pumpe d bac k int o th e pipe s t o hel p condensation ; th e res tgoe s t o th e ammoni a still , which release s th e ammoni a for subsequen tchemica l combinatio n in th e saturator . Al l th e tar flows to storag e tank s fo r ta r distiller s or for fuel. 8 Figur e 5. 3 ca n b e divide d into differentsteps , representin g th e flow of material through th e variou s piece s o

f equipment , wherei n th e prope r physica l operatio n or chemica l conversio n take s place . Figur e 5. 3 ma

y b e thu s broke n down int o th e followin g sequences : Coa l i s transferred , crushed , an d screene d (Op) . Coa l i s charge d to a hot , empt y ove n (Op)*

. Coa l i s chemicall y transforme d t o cok e an d volatile s b y pyrolysi s (Ch) . Ho tcok e i s pushe d ou tof th e oven , quenched , an d transporte d (Op) . Condensabl e products of distillatio n ar e liquefie d an d collecte d i n th e hydrauli c mai n (Op) . Fou l ga s i s cooled , an d tar extracte d (Op) . Ammoni a i s remove d fro m ga s a s ammoniu m sulfat e (Ch) . Ca s i s coole d and subjecte d t o benzo l an d toluo l removal by absorptio n in stra w oi l (Op) . Hydroge n sulfid e i s remove d (Ch) . Purified ga s i s metere d an d transferre d t o consumer s (Op) . Th e ta r separate d fro

m th e collectin g mai n an d th e tar extracto r or electrostati c precipitator s i s settle d fro

m ammoni a liquo r and , togethe r wit h ligh toil , subjecte d to th e sequence s represente d by th e flowchart(Fig . 5.6) . Koppers-Becke r oven s are th e mos twidel y use d vertical-flu e oven s in th e Unite d States . Th e elevatio n i s show n i n Fig . 5.4 . Thes e oven s ar e al l o f th e regenerativ e typ e an d hav e individua l hea t regenerators , generall y fro m sid e t o side , underneat

h th e oven . Th e reversal of th e ai r an d waste ga s flow i s mad e fro

m sid e to sid e ever y half hour . Th e ga s burn s upward , crosse s ove r th e to p of th e oven , come s downward o n th e othe r side , an d exit s through th e regenerativ e ove n underneath . Thi s travel i s completel y reverse d periodically . RECOVER

Y O F COA L CHEMICALS

* Th e gaseou s mixtur e leavin g th e ove n i s mad e u p o f permanen tgase s whic h for m th e final purifie d coke-ove n coa l ga s for fuel , accompanie d by con densabl e wate r vapor , tar , an d ligh toils , wit h soli d particle s of

coal dust , heavy hydrocarbons , an d comple x carbo n compounds . Th e ga s i s passe d from th e foul mai n (Fig . 5.3 ) into th e primar y con dense r an d coole r a

ta temperatur e of

abou t165°F . Her e th e gase s are coole d to 85° F b y mean s of water . Th e ga s i s conducte d t o a n exhauster , whic h serve s t o compres s it . Durin g th e compressio n th e temperatur e of

th e ga s rise s to a s hig h as 120°F . Th e ga s i s passe d t o a final ta r extractor , wher e th e tar i s thrown ou tb y impingemen tof ga s jet s agains tmetal surfaces . In newe r plants th e tar extracto r ma

y b e replace d b y electrostati c precipitators . O n leavin g th e tar extractor , th e ga s carrie s three-fourth s of

th e ammoni a and 95 % of th e ligh toi l originall y presen twhe n i tlef tthe ' oven . Th e ga s i s le d t o a saturator(Fig . 5.3) , which contain s a solutio n o f 5 to 10% 1 0 sulfuri c acid , wher e th e ammoni a i s absorbe d wit h th e formatio n o f

soli d an d crystallin e ammonium sulfate . Th e saturato r i s a lead-lined , close d vessel , wher e th e ga s i s fe d i n b y a serrate d distributo r underneat h th e surfac e of

th e aci d liquid . Th e aci d concentratio n i s maintaine d b y th e additio n o f 60°B e sulfuri c acid , an d th e temperatur e i s kep ta t140° F by th e reheate r an d th e hea tof neutralization . Th e crystallize d ammoniu m sulfat e i s remove d fro m th e botto m o f th e saturato r b y a compressed-ai r injector , or a centrifuga l pump , an d draine d o n a table , fro m which th e mothe r liquo r i s ru n back into th e saturator . Th e sal ti s drie d i n a centrifug e and bagged , usuall y i n 100-l b sack s (Chap . 18) . "Lowly , op. cil.. Suppl . Vol. , pp . 462-471 . fo r othe r type s o f ovens . 9 Detail s fo

r thi s recover

y o f the man y coa l chemical s are t

o b e foun di n Lowry . op. cit., Suppl . Vol. , pp . 618-628 , fo r u r processing , pp . 629-674 , fo r light-oi l processing ; ECT . 2

ded. . vol . 2 . p . 299 . 1963 . 10 A t the su n o

f t charge , the acidit

y i s ofte n a ahig h a s 25% . but

ammoniu mbisulfat e i s liable t

o b e forme dwhe n fre e sulfuri c aci dexceed s 1 0 t

o 11% . VM " t

OiP- r •30*/J - »

S-* - I -mmom

a I th e ta r •ugl i th e > n take s

'P. * (Op) . ipttators resente d tes . Th e lua l heat i d wast e i e to p of lerneath . l e u p of b v con - •ons . and lar v con i v mean s lpressio n >r . wher e s th e ta r is carrie s oven . trie acid , ate . Th e •derneat h e sulfuri c ion . The ressed-ai r bac k into p . 18) . 528 , fo r u r fre e sulfuri c Coking of Coal 7 3



# fP l-y.-vfirg.jgg ? 

# Wl^

_-S- r_ U J j r 1 ' , gar ? •*•* - v^T W

Fig. 5. 6 Flowchar

t o f coal-ta r continuou s distillatio n (withou t ta r dehydration) . Th

e pipe .lil l i . u

f th e radian t t * pe . Th e erude-ta r fee dinle t i s a t the lowe r right. Thi

ai s filtere dandpumpedthrough the reflu x vapor-ta r hea t exchanger , economizer, pitch-ta r hea t exchange r int o the to p o f the lowe r thir do f th e distillatio n colum

n andou t a t the bottom , t

o the circulating pump s an

dint o th e pip e stil l (wher e th e crud e u r join s 4 t o 5 volume s o

f the circulatio n pitc

h an do n finall v t o nea r the to p o f th e distillation columnl . Th e vapors , steam-distille

dan dsuperheated , pas s overhea dfro mthe to p o f the tray-tvp e distillation column , enter the botto mo f the bubble-ca p fractionating column , an dare separatedint

o fou r fractions : 1.2.3.4 . wit

h aresidue . 5 . leavin

g a t th e botto mo f thi s fractionatin g column . Th

e produc t pitch . 6 . cascade s fro

mth e to p o f the distillatio n colum

n dow n throug h the superheate d steaming sectio n t o establish the desiredpitc

h hardnes s an

dt o stri p th b pitc

h o f the higher-boilin

g volatil e oils . I t i s the n withdraw

n fro m abov e th e middl e o f th e distillatio n colum

n andconducte dthrough th e pitch-ta r hea l exchange

r t o storage . Th e product s are : Sid e strea m1 : Ligh

t oil . b p t o 170°C . Sid e strea m2 : Carboli

c oil . b p 170-205°C . Sid e strea m3 : Naphthalene "oil. b

p 205-24O*'C . Sid e strea m4 : Creosot

e o r was h oil . b p 240-280"C . Residu e 5 : Th

e residue o

r anthracene , b

p 270-340°C . Pitc h 6 : Residuu

mo r pitch , b p 325-400°C . lher e ar e standb y stea mpump s i

n th e even

t o f failur e o f th e motor-drive

n pumps . Th e Wilto

n principl e o f

recirculation o

f ho i pitc h a t 350° C mixe

dwit h th e crude u r

a t 120° C rise s th

e temperatur

e o f -th e pitch-ta r leavin g th e pipe stil l t o on h 350° C an

d avoid s thermal-cracking andvaporization i n th e pip e still . {Chemical Engineering. Wiltons Ltd.. London. Se e specia l pamphlet s fro mthi s compan

y fo r details. )
Th e ga s leavin g th e saturato r a tabout140° F i s take n t o final cooler s o

r condensers , where " i s scrubbe d wit h wate r unti l its temperatur e i s 75°F . Durin g thi s coolin g som e naphthalen e separate s and i s carrie d alon g with th e wastewate r an d recovered . Th e ga s i s passe d int o a light-oil o r benzol scrubber(Fig . 5.3) , ove r whic h i s circulated , a tabou t75° F a s th e absorben tmedium , a heav y fraction o

f petroleu m calle d straw oil. or sometime s a coal-ta r oil . Th e stra w oi l i s sprave d mt o the top o

f th e absorptio n towe r whil e th e ga s flows u p throug h th e tower . Mostscrubber s us e s pua l meta

l packing , althoug h woode n grid s were formerl y used . Th e stra w oi l i s allowe d t

o absorb snou t2 t o 3 % o f it s weigh to f

ligh toil , wit

h a removal efficienc y o f about957 c of

th e light-oi l vapo r " 1 th e gas . In e ric h stra w oil . afte r bein g warmed i n heatexchanger s b v vapors fro m th e light-oi l stil l an

d "•e n b y hoi debenzolize d oi l flowing ou tof th e still , i s passe d t

o th e strippin g column , wher e th e stra w oil , flowing downward , i s brough tint o direc tcontac twit h liv e steam . Th e vapors of th e ligh t ° " an d stea m pas s of

f and upwar

d fro m th e stil l through th e heatexchange r previousl y mentione d int o a condense r and wate r separator . Th e lean , or stripped , stra w oi l i s returne d throug h th e ea texchange r r

o th e scrubbers . Th e gas . afte r bein g strippe d of it s ammoni a an

d ligh toil , ha

s th e 

# I

• > ! V i f 5 

# 37 4 [Chap. S] Coal Chemical* TABL E 5. 3 Approximate Yield*per Ton of Coat Carbonized (Depending on Owl

and Conditions L

acd,Hightemperature. lb Lowtemperature, lb Furnac e cok

e Cok e breez e Semicok e (12 % volatiles ) Ta r Ammoniu msulfat e Ligh t oi l (remove dfro mgas oi l scrubbing ; se

e Tabl e 5 Ca s b v -4 ) 1.43 0

9 3 7 8 2 0 2 0 3.50 0 1.440

15 0 1 8 1 6 25 0 Source . Ind. Eng. Chem. 48 , 35 2 (1956) . Se e als o Fig . 3.3 . Not

e tha t 4 l b o f technica l ammoniu msulfat e i s equivalen

t t o 1 l b o f ammonia . sulfu r remove di

n purifvin g boxes , whic h contai n iro n oxid e o n woo dshavings , o r bv asolutio n o

f ethanolamin e (Girbotol ) i n scrubbin g towers , th e bes t present-da v practice . Thes e procedure s ar e full y describe di n Chaps . 6 an d7 . U.S . Stee l ha s buil t

acoke-ove n plan t

a t Clairton . Pa., 1 1 whic h emplov s ne w processing , furnish

in g aclea n ga s fo r

compressio n an dhvdroge n recover v an davoidin g coproductio n o f ammoniu m sulfate . Th e ke v t o th e ne w proces s i s arecycle dsolutio n of ammoniu mphosphat e tha t absorb s N'H 3 fro mth e coole d(compressed? ) coke-ove n gas . I n atypica l absorptio n cvcle . lea n 40 % phosphat e solutio n (th e mola r

rati o of NH 3 t o H 3 P0 4 i s les s tha n 1.5 ) soak s u p al l bu t trace s of NH 3 . Th e ric h ammoniu mphosphat e solutio n i s reboile di n adistillatio n towe r i n whic h NH 3 vapo r

an dalean phosphat e solutio n ar e separate dfo r reuse . LOW.TEMPERATUR

E CARBONIZATION 1 5 I n thi s centur y alarg e amoun t of experimenta l wor k ha s bee n carrie dou t

o n th e carbonizatio n o

f coa l a t temperature s rangin g fro m75 0 t o 1100°F . wit h th e mai n objec t

of obtainin g maximu mvield s of liqui dproduct s an dproducin g semicoke s containin g fro m8 t o 20 % volatil e matter . Her e agai n th e characteristic s an dvield s o f th e variou s product s depen dupo n th e coal , th e temperature. * an dth e treatment . Table s 5. 3 an d5. 5 sho w th e differenc e i n ga s conten t an di n yiel dproduct s fo r high

- an dlow-temperatur e svstems . Th e Disc o plan t a t McDonald , Pa. , i s th e onl v plan t i n this countr y t o utiliz e alow-temperatur e carbonizatio n process 1 3 an dha s adail y capacit y t o conver t high-volatil e coa l int o 80 0 ton s o f Disc o char , adomesti c fuel . Th e ta r

i s sol dan drefine dt o produc e tar-aci doil , ta r acids , "creosote," 1 4 an dfue l pitch . Th e gas , afte r liquid-produc t

removal , i s use dfor

firing. Th e maximu mtemperatur e use di n thi s proces s i s 1050°F . Low-temperatur e carbonizatio n ha s bee n importan t i n severa l Europea n countries , especiall y England , fo r

man y decades , bu t

ha s neve r

bee n popula r

i n th e Unite dStates . DISTILLATIO N O F COA L TAR 1 3 Coa l ta r i s amixtur e o

f man v chemica l compounds , mostl y aromatic , whic h var v widel y i n compositio n (Figs . 5.2 , 5.6 . an d5.9) . I t i s acoproduc t

of th e destructiv e distillatio n o r pyrolvsi s o

f coal . Mos t of th e ta r i n thi s countr y i s produce db v stee l companie s a s acoproduc t fro mblast-furnac e cok e "Coo l Cai n fo r AmmoniaRecovery . Chem. Keek. Feb . 27 . 1965 . p . 39 : U.S . Pat . 3.024.090 . '••Low***** , op. cit.. Suppl . Vol. , chap . 10 . pp . 395-46 0 (13 8 refs.) . l3 Lowrv , op. cit., Suppl . Vol. . p . 439 . 14 B v definition o

f th e America

n Woo dPreserver s Association : however, creosot e i s adistillat

e o f high-temperatur

e coke-ove n tar . 15 <_f . Bituminou s Material s i

n Roa d Construction , pp . 26ff

, Dep t o f Scientific an

dIndustria

l Research . HMSO , London .Distillation of Coal Tar7 5 production . Th e qualit y an dquantit y of ta r fro mthi s operatio n wil l varv . dependin g o n th e rat e of productio n of

th e oven s an dth e natur e o f th e coa l used . Th e specifi c gravit y will var v fro m1.1 5 to 1.2 . an dth e quantit v of ta r will vary fro m8 to 1 2 gal o f ta r pe r to n of coal . A tvpica l light-ta r compositio n i s show n i n Fig . 5.9 . Th e en dproduc t of th e distillatio n (Fig . 5.6 ) of coa l ta r i s pitch , usually mor e tha n 60 % o f th e crud e tar . Th e object s o f th e distillatio n ar e t o produc e asalabl e en d product , wit

h aseparatio n o f

th e valuabl e product s int o usefu l cuts . I n amoder n refiner v equippe d wit h afractionatin g colum n (Figs . 5. 6 an d5.8 ) fo r th e primar y distillation , thes e product s mus t usuall v b e sharpl y fractionated , wit h aminimu mof

overlapping . Th e proces s als o shoul db e thermall y economical , an dth e furnac e (Figs . 5. 6 an d5.7 ) s o designe dan dconstructe dtha t repair s an dfuel usag e ar e a

t aminimum . METHOD S O F DISTILLATIO

N Ther e hav e bee n man y improvement s i n coal-ta r

distillatio n ove r th e vears . Thes e ca n b e divide dint o thre e genera l classifications :

asolutio n o

f ocedure s ar e sing , furnish

f ammoniu m absorb s NH 3 7 c phosphat e f 3 . Th e ric h an dalean •xperimenta l itollOOT . » semicoke s th e variou s >.5 sho w th e Th e Disc o jrbonizatio n

. adomesti c i pitch . Th e this proces s i countries .

ompositio n coal . Mos t rnac e cok e

••oke-oven tar . •ISO . London . 1 . Th e 3.000

- t o 10.000-ga l batc h still , whic h ha s bee n muc h improve dan duse dfo r specia l en dproduct s suc h a s pip e ename l (Fig . 5.7) . 2 . Th e continuou s still , wit h asingl e distillatio n column , usin g sid e stream s (Fig . 5.6) . 3 . Th e continuou s unit , usin g multipl e column s wit h reboiler s (Fig . 5.8) . PRODl'CT S O F DISTILLATIO N Moder n practice , a s exemplifie db y th e pip e stil l an dfrac

tionatin g columns , i s producin g suc h clea n cu t fraction s tha t

ofte n littl e furthe r

purificatio n i s necessary . However , i n Fig . 5. 6 an dbelo w ar e give n th e fraction s obtaine di n a n ordinar y continuou s distillation , whic h will var v wit h th e coal an dwit

h conditions . a. Light oils usuall v compris e th e cu t u p t o 390°F . The v ar e first crudel v fractionate dan d agitate da t alow temperatur e wit h concentrate dsulfuri c acid , neutralize dwit h causti c soda , an d redistilled , furnishin g benzene , toluene , an dhomolog s (Tabl e 5.4) . b. Middle oils, o r

creosote oils, generall y ar e th e fractio n fro m39 0 t o 48 0 o r 520 ° F . whic h contain s naphthalene , phenol , an dcresols . Th e naphthalen e settle s ou t upo n cooling, i s separate d


## : 

# n

in

(,'*•• • S * 7 T «*distUlatio n batc h tan k still , heate db v ga s o r oi l burnin g i n larg e retur n ben d « wit h abou t 70 % therma l efficiency . Tw o stirrers . (Reilly Tar & Chemical

Co.)•raB8SJg6WBW!«JP5 <

Fig. 5. 8 Fractionatin g distillin g colum n (14 7 f thigh ) a tClairton . Pa. , producin g high-quality benzene , toluene , an d xylene . (U.S. Steel Corp.)

b y centrifuging . and is purifie d by sublimation . Afte r th e naphthalen e i s removed , pheno l an d othe r ta r acids 1 6 are obtaine d b

y extractio n wit

h a 10 % causti c sod a solutio n an d neutralization , o r "spring ing, " b y carbo n dioxide . Thes e ar e fractionall y distilled . c. Heavy oil

ma y represen tth e fractio n fro m 48 0 to 570°F , o r i tma y b e spli tbetwee n th e middl e oi l an d th e anthracen e oil . d. Anthracene oil

i s usuall y th e fractio n fro m 52 0 or 570° F u

p to 66 0 o r 750°F . I

ti s washe d wit h variou s solvent s t

o remov e phenanthren e and carbazole : th e remainin g soli d i s anthracene . MISCELLANEOU

S I SE S O F COA L TA RI n 197 6 coal ta

r use d a s fuel amounte d t o about1 5 to 20 % of

th e total consumptio n o f tar for th e vear . Coa

l ta r i s als o utilize d for road s an d roofs . Fo r thes e purpose s th e ta

r i s distille d u

p t o th e poin twher e therma l decompositio n starts . Thi s "bas e tar " i s the n oile d bac

k wit h creosot e oi l t

o ensur e satisfactory rapid drying . Somewhatsimila r tars ar e use d t o impregnat e fel tan d pape r fo r waterproofin g materials . FRACTIONATIO

N AN D PURIFICATIO

N O F COA L TA RCHEMICAL

S Largely becaus e o f th e presen tcompetitio n amon g aromati c chemical s fro m petroleu m (Chap . 38) , interes tin aromatic s
16 "Ta r acids, " i n th e languag e of th e tar distiller , represen tpheno l an d it s homologs , whic h are solubl e i n causti c soda . tV., ,

*••>• , C -, H H 2 • 3 • VTABL E 5. 4 Typical

Composition of

Light Oil from Gas

Benzen e Toluen e Xylen e an d ligh tsolven tnaphth a Aci d washin g loss (mostl

y unsaturated! ) Heav y hydrocarbon

s an d naphthalen

e Was h oi l Tota l crud e ligh toi l Pur e moto r fractio n Gallons per ton of coal 1.85 0.4 5 0.3 0 0.1 6 0.2 4 0.2 0 3.2 0 2.5 0 Source: Lowry . Chemistr y o f Coa l Utilization , vol . 2 . p . 940 : mor e detaile dtabulation . Suppl . Vol. . pp . 633-642 . Coal to Chemicals 7

7

fro mcoa l ta r ha s temporaril y decrease d(se e Tabl e 5. 2 fo r mai n products) . Also , svntheti c processe s fro macetaldehvd e an dammoni aar e supplvin g th e increase ddemand s fo r pyridine , of

whic h coal ta r a t one tim e wa s th e sol e supplier . Thi s i s als o tru e of pheno l (Chap . 34) . I n Europe. 1 7 whic h ha s muc h coa l an dlittl e petroleum , ther e i s continue dinteres t i n coa l chemicals . Tabl e 5. 6 list s som e solidchemical s tha t

cou W b e obtaine dfro mcoa l tar . Th e produc t o f larges t potentia l i s phenanthrene (the secon dmos t

abundan t

i n coa l tar) , of

whic h Franc k

estimate s tha t

250,00 0 ton s ca n b e recovere d i n th e Wester n worl dyearl v a s soo n a s profitabl e use s ca n b e found . Thi s i s base do n atota l recover v o f 1 0 millio n ton s o f

crud e ta r

an dwith a50 % yield . Anthracene, o r rathe r anthraquinon e (Chap . 39) , i s th e basi s of

man y va t

dyes , bu t

her e agai n i t

i s cheape r

t o synthesiz e thi s compoun d(Chap . 39 ) fro mphthali c anhydrid e an dbenzen e o r preferabl y chlorobenzene . 

# 1

ol an dothe r

. o r "spring

betwee n th e I t i s washe d anthracene , to abou t 1 5 droofs . Fo r i s "bas e tar " lila r tar s ar e
us e o f th e •i n aromatic s i n causti c soda . COA L T O CHEMICAL S Thi s sectio n consider s th e res t of th e processe s liste di n Tabl e 5.1 , excep t thos e designate dfo

r discussio n i n othe r

chapters . I n al l case s furthe r detail s ar e availabl e i n th e references , especiall y i n th e monumenta l thre e volume s edite db y Lowry . Solvent extraction of

coal s an dlignite s ha s bee n trie da t temperature s belo w an dabov e 300° C an dwit h an dwithou t

mil dhydrogenation . Althoug h variou s resin s an dwaxe s result , th e processe s hav e me t onl y mino r

commercia l acceptance. 1 8 Alkaline hydrolysis 1 9 ha s likewis e bee n investigated , wit h meager results . Partial

oxidation yield s th e tremendousl y importan t synthesis gas (Chap . 7) . TABL E 5. 5 Variation of

Gas from Lose- and

High-temperature Coal Carbonisation Cat co 2 C O
C H « an d homolog s Coking temperature,

500 C % 9. 0 8. 0 5. 5 10. 0 65. 0 2. 5 Coking temperature,

10OO C. % 2. 5 3. 5 8. 0 50. 0 34. 0 2. 0

"Franck . Th

e Challenge i

n Coa l Ta r Chemicals , Ind. Eng. Chem.. 55(5) , 3 8 (1963) . Man v coa l chemical s described . '"Lowry , op. cit.. Suppl . Vol. , p . 1089 . Uwrv , op. cit.. Suppl . Vol. , p . 1090 .P.3 0



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PRODUCER S AM D CAPACITIE S - CRESOL S AN D CRESYLI C ACID S - MILLION S O F POUND S NATURA L PRODUCER S LOCATIO N198 6 CAPACIT Y Meriche mHouston , T X 12 0 PM C Specialtie s Sant a F e Springs , C A3 0 Stimso n Lumbe r Compan yAnacortes , W A2 0 Mobi l Joliet , I L 4 Crowle yTa r Product s Kent , O H 1 SYNTHETI C PRODUCER S PM C Specialtie s Chicago , I L 3 0 Genera l Electri c Plastic s Selkirk , N Y 20 0 TOTA L Natura l an d Syntheti c 40 5 Sherwi n William s sol d it s par a creso l plan t t o PM C Specialtie s i n Jul y1985 . Conoc o close d a 5 0 m mlb. , Newark , NJ , syntheti c plan t i n Ma y1983 . Diamon d Shamroc k close d a plan t i n Tuscaloosa , AL , and lease s par t t o Meriche mt o manufactur e naphtheni c acid . Genera l Electri c produce s syntheti c 2,6-xyleno l whic h i s use d t o mak e polyphenylen e oxid e a t Selkirk , NY . Genera l Electri c als o produce s 2,3,6-trimethy l pheno l whic h i s use d a s a n antioxidant . PM C purchase d th e Ferr o plant * i n earl y1986 . EN D USES....Th e majo r en d use s fo r cresol s an d cresyli c acid s ar e i n wir e ename l solvents , phenoli c resin s an d agricultura l chemicals . Par a creso l i s use d t o produc e 2,6-di-tert-butyl-p-creso l (butylate d hydroxy
toluen e o r BHT) . BH T i s a leadin g antioxidan t use d i n r e r an d plastic s an d t o a lesse r exten t i n food . Orth o creso l deman d increase d rapidl ybecaus e o f th : is e i n consumptio n o f epox ycreso l novai:

- .' : use d t o mak e compute r chips . Thi s le d t o a n increas e i n pre*. * ..tio n o f syntheti c o-creso l by*;such comp; . s a s Genera l Electric , Syntheti c Chemica l i n th e Unite d Kingdom , an d Nippo n Stee l i n Japan . o-Creso l als o use d i n th e manufactur e o f MCPA , 4-chloro-2-methy l phenoxyaceti c aci d an d 2,4-dinitro-ortho-creso l N0C) . Met a creso l i s use d i n th e manufactur e o f thymol , a n ingredien t use d b yth e pharmaceutica l industr y fo r col d and coug h medicine . m-Creso l i s als o use d i n th e productio n o f syntheti c pyrethroid s fo r insecti

cid e us e i n cotto n fo r bol l weevi l control . Cresyli c aci d mixture s ar e use d extensivel ya s intermediate s i n th e productio n o f wir e ename l sol
vents , phenoli c resins , an d phosphat e esters . Variou s mixtures , mainl ym- , p-cresols , o r cresyli c acid s wit h hig h m-conten t ar e th e preferre d product s fo r us e i n phenoli c o r epox yresins . Th e marke t fo r phosphat e ester s ha s stabilize d an d no w onl yrepresent s abou t 8 % o f th e deman d fo r cresylics . I n phosphat e este r production , lo w ortho , meta-par a an d mixe d xylenol s ar e use d extensivel yt o produc e a variet yo f grade s fo r us e a s flam e retardan t plasticizers , fir e resistan t hydrauli c fluids , an d oi l additives . Othe r en d use s fo r cresol s an d cresyli c acid s includ e or e flotatio n frothers , disinfectants , fibe r treatments , tannin g agents , an d meta l degreasin g agents . EN D US E PATTER N- 198 5 ESTIMATE D DERIVATIV E PERCEN T Wir e Ename l Solvent s Phenoli c Resin s Agricultura l Chemical s Phosphat e Ester s Disinfectant s an d Cleanin g Compound s Or e Flotatio n Miscellaneou s 2 0 1 8 1 2 9 6 5 3 0 MANUFACTURING....Cresyli c acid s an d cresol s ar e by-product s o f petroleu mcatalyti c crackin g o r coa l ta r distillation . Natura l cresol s an d cresyli c acid s ar e recovere d b yextractio n o f th e spen t causti c liquo r use d t o was h petroleu mdistillate s suc h a s cracke d naphtha . Th e cracke d naphth a i s passe d throug h a verti

ca l colum n an d th e filtrat e containin g phenol , cresols , an d xylenol s i s extracte d wit h sodiumhydroxide . Furthe r fractionatio n mayb e use d t o produc e a variet yo f product s tailore d t o mee t specifi c requirements . Coa l ta r acid s ar e recovere d b yextractio n o f th e ta r aci d fraction , usuall ya ligh t oi l cu t i n th e distillatio n process . Th e phenols , cresols , an d xylenol s ar e recovere d i n crud e formb yacidificatio n o f th e aqueou s solutio n usuall yb yinjectin g carbo n dioxid e followe d b ygravit ysettling . Th e crud e phenol s ar e the n fractionate d t o obtai n phenols , cresols , an d xyleno l isomers . I n th e manufactur e o f syntheti c cresols , ther e ar e severa l routes . Th e mos t commonl yuse d proces s i s th e vapo r phas e methylatio n o f phenol . PM C Specialtie s produce s high-purit yp-creso l b ytoluen e sulfona
tion . Other s produc e creso l mixture s fro mcymene , obtaine d b yth e alkylatio n o f toluen e wit h propylene . ENVIRONMENTA L ASPECTS....Cresol s an d cresyli c acid s requir e a corrosiv e an d poiso n labe l t o mee t DO T stan dards . Protectiv e equipmen t i s required . Whe n handling , fac e shield , respirator , chemica l gloves , an d slicke r sui t als o used . Exposur e ca n caus e damag e t o lung , liver , eyes , kidneys , an d th e nervou s system . Th e EP Arecentl ypublishe d a rul e requirin g creso l producer s t o initiat e a testin g progra mfocusin g o n possibl e mutageni c an d carcinogeni c effect s o n exposur e t o thre e creso l isomers : ortho , para , an d met a cresol , an d cresyli c acid . Th e firs t tie r o f tes t result s wil l determin e th e nee d fo r ionge r ter massay s an d nuerotoxicit ystudies . Industria l source s indicat e tha t a join t testin g progra mi s wel l underwa yt o compl ywit h al l phase s o f th e EP Arequirements .

T o th e bes t o f ou r knowledg e th e informatio n containe d herei n i s accurate . However , w e d o no t assum e an

yliabilit ywhatsoeve r fo r th e completenes s o r accurac yo f thi s report .P.3 2

(P/umi<

'&IA4tuCt& m->ktt9flt\t , d NOVEMBE R198 5 Previou s Repor

t —Januar y 198 0 A Reportin g Service o f Chemica l Product s Corp . Cortland , Ne

w Yor k 13043-023 0 

### CRESOL S & CRESYLI C ACID S FOCUS....Cresol s an

d cresyli c acid s ar e subcategorie s o f a grou p o f chemical s calle d ta r acids . Ta r acid s consis t o f phenol s an d substitute d phenols . Thes e ta r acid s ar e recovere d b y extractio n fro

m chemica l oi l derive d fro

m eithe r coa l ta r distillatio n or petroleu m cracking . Th e extractio n i 6 usuall y accomplishe d b

y causti c solutions . Th e crud e phenol s ar e fractionate d t o obtai n phenols , cresols , an d highe r boilin g phe nol s an d xylenols . Thes e compound s or phenoli c mixture s al l hav e boilin g point s betwee n 180-230°C . Cresol s ar e define d a s phenoli c mixture s i n whic h505 » o f th e materia l boil s below 204°C . Cresol s exis t i n severa l form s includin g ortho , meta , an d par a isomers . The y ar e usuall y

supplie d a s mixture s (meta , para ) or a s (ortho , meta , an d para ) bu t ca n als o b e purchase d a s individua l isomers . Cresyli c acid s ar e define d a s phenoli c mixture s i n whic h50 % o f th e materia l boil s abov e 204°C . Cre syli c acid s includ e hig hboilin g mixture s o f cresol-xylenols , mixture s o f xylenol s an d hig hboilin g ta r acids . I n recen t years , severa l companie s includin g Genera l Electri c Plastic s hav e starte d t o produc e syn theti c alkylate s suc ha s 2,6-xylenols , orth o cresol , an d cresyli c acids . Worl d deman d for 2,6-xyleno l i s currentl y

estimate d a t 12 0 thousan d metri c ton s pe r yea r wit hGenera l Electri c manufacturin g 10 0 thousan d metri c ton s for makin g polyphenylen e oxid e (PP0) . Cresol s an

d cresyli c acid s ar e recovere d b y extractio n o f coa l tar s or petroleu m naphth a fro

m cataly ti c cracking . Productio n o f th e thre e creso l isomers , ortho , par a an d met a creso l an

d cresyli c aci d totalle d 117. 5 millio n pound s i n 1985 . Import s accounte d fo r a n additiona l 14. 9 millio n pounds . Domesti c productio n ha s decline d steadil y sinc e 197 4 whe n a hig ho f 19 1 millio n pound s wer e produced . Th e decreas e i n outpu t result s fro m th e declin e i n th e productio n o f phosphat e ester s produce d fro m natura l cresyli c acid s fo

r us e a s flam

e retardan t plasticizer s an d fir e resistan t hydrauli c fluids . Ove r th e pas t fiftee n years , th e tren d ha s bee n towar d th e us e o f alkylphenol s whic har e substitute s fo r th e natura l cresol s use d t o mak e phosphat e esters . Th e switc ht o syntheti c phosphat e ester s wa s cause d b y performanc e an

d economi c factors . Th e productio n o f natura l phosphat e ester s decline d fro m 7 0 millio n pound s i n 197 0 t o les s tha n 1 0 millio n i n 1985 . Othe r factor s affectin g th e declin e ar e lowe r operatin g rate s an d increase d efficienc y

a t oi l refinerie s an d stee l mill s i n recen t years . Thes e operatin g change s reduce d th e availa bilit y o f spen t refiner y bottom s an

d coal-tar s tha t ca n b e fractionate d fo r recover y

o f pheno l alkylates . Ther e hav e als o bee n increasin g environmenta l an d healt hconcern s abou t th e us e o f natura l cresols . OUTLOOK....th e surplu s o f petroleu m product s wil l continu e t o b e a facto r i n th e availabilit y o f spen t refiner y bottom s an

d natura l feedstocks . Industr y forecast s indicat e change s i n deman d fo r petroleu

m prod uct s wil l occu r i n 1989-9 0 whic hwil l increas e th e suppl y o f natura l feeds . Th e tren d t o produc e selecte d grade s o f syntheti c alkylate s wil l continu e a s ne w productio n techniques ar e developed . Producer s o f spe cifi c grade s o f alkylate s includ e Bayer , Britis hSyntheti c Chemical , Nippo n Stee l an d Genera l Electric . BH T (butylate d hydroxytoluene) , a n antioxidan t use d primaril y i n rubbe r an

d plastic s an

d manufacture d fro m par a cresol , wil l continu e t o declin e i n us e a s substitutio n o f hig hmolecula r weigh t phenoli c anti oxidant s ar e made . Also , th e us e o f natura l cresyli c acid s fo r phosphat e este r productio n wil l continu e t o decline . Th e expor t marke t for cresol s an d cresyli c acid s wil l remai n important . PRICING....Competitio n fro m syntheti c cresol s an d cresyli c acid s wil l kee p price s fo r th e natura l mater ial s stable . Adequat e supplie s o f al l grade s an d depresse d price s for petroleu m feedstock s wil l als o kee p price s ver y

sensitiv e t o condition s o f purchase . Depresse d price s ar e expecte d t o remai n nea r curren t level s unti l 198 8 or 1989 . AVERAG E PRIC E RANG E - CRESOL S AN D CRESYLI C ACID S Cent s Pe r Pound - Tank s - Freigh t Equalize d 196 0 196 5 197 0 197 5 198 0 198 2 198 3 198 4 198 5 198 6 198 8 199 0 Trad e Lis t o-Creso l m/p-Cresol s p-Cresol Cresyli c Acids-r e SUPPL Y AN D DEMAND . Capacit y Productio n o-Creso l Tota l Cresol s Cresyli c Acid s Tota l Productio n Cresols-Cresyli c 1 6 18 *

2 2 1 8 5 2 5 0 •fine d ...Million s 196 0
2 1 6 7 5 6 Acid s 12 3 Syntheti c Alkylate s 

### 19 4 20 * 4 7 15 ' o f Pound s 196 5 20 3 3 3 7 1 5 1 12 2 41 * 4 8 7 2 4 4 

### 61 4 6 0 12 5 5 4 ....Estimate d 197 0 22 5 2 3 9 1 9 8 18 9 197 5 25 0 21 9 3 4 5 13 8 7 2 6 1 9 0 4 9 6 8 6 5 9 5 5 2 ...Domesti c U 198 0 28 5 3 0 9 5 3 0 12 5 198 2 32 5 3 5 8 0 3 0 11 0 6 7

6 8 9 5 5 3 .S . 198 3 40 5 4 3 7 5 5 2 12 7 3 0 6 5

7 2 6 5 7 2 10 0 10 0

198 4 40 5 5 5 9 0 4 0 13 0 5 0 6 0

198 5 40 5 6 0
11 8 10 0 6 5

198 6 40 5 6 5 9 2 2 8 12 0 11 0 7 0 7 5 11 0 7 5

198 8 45 0 7 3 9 9

. 3 1 13 0 13 0 7 4 8 5 12 5 8 5

, 199 0 45 0 8 0 10 6 2 4 13 0 15 0 AVAILABILITY....Severa l plan t closing s i n recen t year s hav e bee n offse t b y the . entry

o f syntheti c alkyl ates . Adequat e capacit y exist s fo

r al l grade s o f cresol s an d cresyli c acids . o-Creso l an d 2,6-xyleno l ar e growin g a t rate s o f 5-75 5 an d 105 . pe r yea r wit hadequat e supplie s availabl e domesticall y an d worldwide . I n earl y 1986 , Ferr o Corporatio n sol d it s Producto l Chemica l Divisio n t o PMC Specialtie s Grou p Inc . o f Rock y River , OH . Producto l Chemical , wit ha plan t i n Sant a F e Springs , C A manufacture s an

d market s alkyl ate d phenols , cresyli c acid s an d naphtheni c acid . PMC produce s syntheti c material s i n Chicago , IL .P.3 3 

# CHEMICA L PROFIL E CRESYLIC S Novembe r 30,198 7 

### SUPPL Y PRODUCE R CAPACITY * Natural : Merichem , Houston , Te x 12 0 Northwest , Anacortes , Was h 8 PMC , Sant a F e Springs , Cali f 3 0 Synthetic : Genera l Electric , Selkirk , N. Y 2 0 PMC , Chicago , II I ^3 0 Tota l 20 8 'Million s o f pound s pe ryear . Natura l cresylic s ar e coaltar - an d petroleum-derive d phenol , cresol s an d xylenols
. PMC' s syntheti c plan t make s p-cresol ; Genera l Elec trics ' make s o-creso l an d xylenols
. PM C acquire d Productol' s Santa F e Spring s facilit y i n January , 1986
. PM C ha s operate d Sherwin-Williams ' Chicag o plan t sinc e July , 1985 ; acquisitio n o f th e plan t wa s complete d i n Septembe ro f thi s year . Profil e las t publishe d 11/12/84 ; thi s revision , 11/30/87
. 

### DEMAN D 1986:10 0 millio n pounds ; 1987:10 5 millio n pounds ; 1991:11 0 millio n pound s (Include s exports ; doe s no t includ e pheno l content)
. 

### GROWT H Historica l (1977-1986) : minu s 3. 2 percen t pe ryear ; future : 0 t o 2 percen t pe r yea rthroug h 1991
. .. . -' 

### PRIC E Historica l (1952-1987) : High , 66c
. pe rpound , cresyli c acid , meta , par a conten t 2 5 percen t o rless , tanks , frt
. alld. ; tow, 10.9c
. pe rpound , sam e basis
. Current : 55c
. t o 60c
. pe rpound , sam e basis
. 

### USE S Exports , 3 5 percent ; antioxidants , 2 0 percent ; phenolic , epox y an d novola c resins , 1 5 percent ; wir e ename l sblvent , 1 2 percent ; phosphat e esters , 5 per cent ; chemica l intermediate , 5 percent ; miscellaneous , includin g cleanin g an d disinfectan t compound s an d or e flotation , 8 percent . 

### STRENGT H Antioxidant s hav e benefitte d fro m plastic s growth , wir e ename l us e i n motor s fro m stron g consume rspending , an d resi n us e fro m a resurgenc e i n US-base d compute rchi p production
. Whil e othe rcresylic s ar e well-balanced , p-creso l i s currentl y snug . 

### WEAKNES S Cresol-base d phosphat e ester s hav e decline d ove rth e pas t severa l years . Or e flotatio n an d cleanin g compoun d us e hav e bee n impacte d b y environmenta l concerns . Wir e production , whil e currentl y o n th e upswing , ha s historicall y bee n falling
. . — 

### OUTLOO K Cresylic s ar e generall y ver y mature : whil e expor t opportunitie s ar e increasing , U S growt h prospect s see m minimal
. Ther e i s a potential , however , fo ravailabilit y o f significan t quantitie s o f cresyli c ra w material s fro m th e Grea t Plain s coa l gasificatio n projec t tha t coul d eventuall y breath e ne w lif e int o th e market
.P.3 4



## I 1 

# ST-Ap - 00?39/>w £



# 198 9 DIRECTOR

Y O F CHEMICA L PRODUCER S UNITE D STATE S O F AMERICA

Informatio n i n thi s Director y i t fo r th o sol o an d privat a us

a o f sponsor

s o f th o Director y o f Chemica l Producers Program .



# RADIA N LIBRAR Y RESEARC H TRIANGL E PARK , N CP.3 5

33 3 RAVENSWOO O AVENU E MENL O PARK, CALIFORNI A 9402 5 (415 ) 859-362 7 FAX : (415)326-551 2 TWX
. 910-373-204 6 TELEX : 33448 6

Copyright O 198 9 SR I International . Unauthorize d us e o rreproductio n o f al l o ran

y par t o f thi s documen t i s prohibited . Printe

d i n U. S AP.3 6

t98 9 DIRECTOR Y O F CHEMICA L PRODUCER S

UNITE D STATE S PRODUC Crayo n orang e (See : Orang e 1 5 i n Organi c Pigment s unde r Pigments ) Creatin e hydrat e Pfanstieh l Laboratories , Inc
. Waukegan , Illinoi s Creatinin e (1-MethyTglycocyamidine ) (1-Methylhydantoin-2 - imide ) Pfanstieh l Laboratories
. Inc
. Waukegan , Illinoi s Creoso l (4-Hydroxy-3-methoxy-1-methylbenzene ) (2-Methoxy p-cresol ) (3-Methoxy-4-hydroxytoluene ) (2-Methoxy-4 - methylphenol ) (4-Methylguaiacol ) Givauda n Corporatio n Chemical s Divisio n Clifton , Ne w Jerse y p-Cresidin e (m-Amino-p-cresol , methy l ester ) (2-Methoxy-5 - methylaniline ) (5-Methyl-o-anisidine ) PMC , Inc
. PM C Specialtie s Grou p Divisio n Cincinnati , Ohi o p-Cresidin e sulfoni c aci d (5-Methyl-o-anisidin e sulfoni c acid ) O-Creso l (o-Cresyli c acid ) (o-Hydroxytoluene ) (2-Methyipheno i (o-toly j alcohol )

Hilton-Davi s Compan

y p-Cresidine-o-sulfoni c aci d Baye rUS A Inc
. Moba y Corporation , subsidiar

y Dyes , Pigment

s an d Organic

s Divisio n Organic s Departmen t PMC , Inc
. PM C Specialtie s Grou p Divisio n Cincinnati , Ohi o

Bush y Park , Sout h Carolin a Cincinnati , Ohi o m-Creso l (m-Cresyli c acid ) (m-Hydroxytoluene ) (3 - Methylphenol ) (m-Toly l alcohol ) Meriche m Compan

y Houston , Texa s Neville-Synthes e Organics , Inc
. Oi l City , Pennsylvani a (m,p>-Creso l Meriche m Compan

y Houston , Texa s Selkirk
. Ne w Yor k Houston , Texa

s Chicago , Illinoi s Houston , Texa

s Genera l Electri c Compan

y GE Plastic

s Meriche m Compan

y PMC , Inc
. PM C Specialtie s Grou p Divisio n (o,m,p)-Creso l Meriche m Compan

y p-Creso l (p-Cresyli c acid ) (p-Hydroxytoluene ) (4-Methylpheno i (p-Toly l alcohol ) Bel l Flavor

s & Fragrance

s inc
. Northbrook , Illinoi s

Oakland , Ne

w Jerse y Meriche m Compan

y Houston , Texa s PMC , Inc
. PM C Specialtie s Grou p Divisio n Chicago , Illinoi s p-Cresol , alkylate d (See : Rubbe rProcessin g Chemicals ) CresoMormaldehyd e resin s (unmodified ) (See : Plastic s an o Resins ) CresoMormaldehyd e sulfonate , sodiu m sal t (See : Hydroxytoluenesulfoni c acid , formaldehyd e condensate , sodiu m salt ) p-Creso l methy l ethe r (See : p-Methylanisol e unde rFlavo ran d Fragranc e Chemicals ) o-Cresolphthalei n Aldric h Chemica l Company , Inc
. Polysciences , Inc
. Milwaukee , Wisconsi n Warrington , Pennsylvani a Cresoti c aci d methy l este r (See : Methy l cresotinate ) m-Cresy l acetat e (See : Medicina l (Pharmaceutical ) Chemicals ) p-Cresy l acetat e (See : p-Toly l acetat e unde rFlavo ran d Fragranc e Chemicals

) Cresy l glycidy l ethe r (1,2-Epoxy-3-{tolyioxy ] propane ) (Glycidy l cresy l ether ) Do w Chemica l U.S A Freeport , Texa s Cresyli c aci d Genera l Electri c Compan

y G E Plastic s Meriche m Compan

y PMC
. Inc
. PM C Specialtie s Grou p Divisio n Stimso n Lumbe rCompan

y Northwes t Petrochemica l Corporation , divisio n Selkirk , Ne w Yor k Houston , Texa

s Chicago , Illinoi s Sant a F e Springs , Californi a Anacortes , Washingto n AD D TOTAL Annua l Capacit y (Million s o

f Pounds ) n a 12 0 3 0 3 0

• 8 18 8 Ra w Materia l Syntheti c Petroleu m Syntheti c Petroleu m Petroleu m 'Plant is currently

shut down and up for sale. Note : Capacities fro m petroleu m feedstoc k are fo rta racids , includin g cresols , natura l phenol , and^em e xylenols
. The y represen t ability t o produce ta racids,
. provide d feedstock

s ar e available
. tj , V • Source : SR I Internationa l estimate s a s o f Januar y 1 , 1989
. ' • , m-Cresyli c aci d (See : m-Cresol ) o-Cresyli c aci d (See : o-Cresol ) p-Cresyli c aci d (See : p-Cresol ) Cresyli c acid-formaldehyd e resin s (See : Plastic s an d Resins

) Cresyli c acid , sodiu m sal t (See : Sodiu m cresoxide ) Cresyli c dithiophosphori c aci d America n Cyanami d Compan y Chemica l Product

s Divisio n Linden , Ne w Jerse y

54 2 SR I Internationa lP.3 7 

# JCJ-ftF-M O

v - *



# KIRK-OTHME R 

# CONCIS E ENCYCLOPEDI A O F CHEMICA L TECHNOLOG Y

PLEAS E D O NO T REMOV E FRO M LIBRAR Y

€

RADIA N LIBRAR Y RESEARC H TRIANGL E PARK . N C AWIIEYINTERSCIENCEPUBLICATIO N Joh n Wile y & Son s NEWYOR K• CHICHESTE R • BRISBAN E • TORONT O • SINGAPOR ECopyrigh t © 198 5 b y Joh n Wile

y & Sons , Inc . All rights reserved . Publishe dsimultaneousl y in Canada . Reproductio n o r

translatio n o

f an y par t o f thi s wor k beyon dtha t

permitte db y Sectio n 10

7 o r 108 o f th e 197 6 Unite dState s Copyrigh t Ac t withou t th e permissio n o f th e copyrigh t

owne r i s unlawful . Request s fo

r permissio n o r

furthe r informatio n shoul db e addresse dt o th e Permission s Department , Joh n Wile y & Sons , Inc . Librar y o f

Congres s Catalogin g i n Publicatio n Data : Mai n entr y unde r

title : Kirk-Othme r

Concis e encyclopedi ao

f chemica l technology . " A Wiley-lnterscienc e publication. " Abridge dversio n o

f th e 2 4 volum e Encyclopedia^ ! chemical technology . 3r

ded . Ne w York : Wiley , cl»8

- C1984 . • . Include s index . . Executiv e editor , Marti n Grayson ; associat e editot ; Davi dEckroth . 1 . Chemistry , Technical—Dictionaries . I . Kirk , Raymon dE . (Raymon dEller) , 1890-1957 . II . Othmer , Donal dF . (Donal dFrederick) , 1904

- . III . Grayson , Martin . IV . Eckroth , David . V . Encyclopedi ao f chemica l technology . VI . Title : Concis e encyclopedi ao f chemical technology . TP9.K5 4 198 5 660-.03'2 1 84-2200 6 ISB N 0-471-86977- 5 Printe d i n th e Unite d State * o f Americ a 

# 4

# K,t-04**t v ALLOS E 73

or para-positio n giv e diphenylmethan e derivative s o n reactio n wit h aldehyde s whic h ar e importan trubbe r antioxidant s (se e Antioxidants) . Condensatio n o f

alkylphenol s wit h formaldehyd e an d dimethylamin e readil y give s th e expecte d Mannic h bases . Alkylphenol s condens e unde r mil d alkalin e condition s wit h acrylat e ester s t o giv e para-substitute d propionates . Mil d condition s ar e neces sar y fo r th e nitratio n an d halogenatio n of mos tphenol s containin g tertiar y alky l group s orth o o r para t o th e hydroxy l group ; otherwise , replacemen tof

thes e group s or 2,5-cyclohexadienon e formatio n ca n tak e place . Alkylphenol s reac treadil y wit h sulfu r mono - an d dichloride s giving , respectively , bispheno l disulfide s an d bispheno l monosulfide s whic h ar e use d a s lubricating-oi l detergent s an d antioxidants . 2,4,6-Tri alkylphenol s an d halogen s o r nitri c aci d reac tt o giv e th e 2,5-cyclohexa dienon e derivatives . Th e onl y oxidatio n product s tha t hav e been considere dcommercially , largel y a s antioxidants , ar e base d o n th e couplin g o f 2,6-dialkylphenol s t o diphenoquinone s b y chemica l oxidatio n o r catalyze d ai r oxidatio n (se e Polyethers) . Manufactur e Th e olefin s use d ar e propylene , 1 - an d 2-butene , isobutene , isopentene , isoheptene , diisobutylene , nonenes , dodecene s an d styrene . Th e alkyla tio n reactio n take s plac e a to r nea r atmospheri c pressur e i n th e presenc e o f protonate d acid s o r meta l phenoxld e catalysts . Alkylation s ma y als o b e performe d ove r soli d acidi c cla y o r molecular-siev e catalysts . Th e natur e o f th e product s obtaine d i n alkylatio n of substitute d phenols , suc h a s cresol s an d xylenols , depend s t o a larg e exten to n th e position s alread y occupie d an d th e size s o f th e alky l group s a s wel l a s th e siz e of th e enterin g alky l group . Th e eas e of

rin g alkylatio n alky l phenol s follo w th e orde r tertiar y > secondar y > primar y > alkyl. Eas e o f alkylatio n o n th e ring positio n i s orth o > par a > meta . On th e othe r hand , th e thermodynami c stabilit y i s jus tabou tth e revers e of th e abov e rates , ie , primar y > secondar y > tertiar y an d met a > par a > ortho . Thus , orth o .-alkylatio n take s plac e readil y eve n wit h mil d meta l phenoxide-typ e catalysts . Mor e drasti c conditions , eg, highe r tempera tures , stronge r catalyst , an d longe r reactio n tim e conver tortho-f-alkyl phenol s t o th e paraisomer s an d finally lea d eithe r t o de-t-alkylatio n o r isomerizatio n t o th e meta-isomer . On th e othe r en d of th e spectrum , on e find s tha tmeta-primary-alkylphenol s ar e th e mos tstable . Thu s bot h coa l ta r (1000°C ) wit h aluminu m chlorid e catalysi s (RT ) produce s a 2: 1 meta/par a cresol isome r ratio . Alkylation-dealkylatio n wit h isobutylen e wa s use d t o separat e metafro m petra-cresol . Thi s i s base d o n th e fac ttha tp-creso l wil l di-f-buty lat e i n th e orth o position s givin g th e lowe r boilin g derivativ e wherea s m-creso l yield s th e highe r boilin g 2,4-di-_-butyl-5-methylphenol . (Th e 6-positio n doe s no tt-butylat e owin g t o excessiv e steri c hindrance) . Som e example s ar e show n i n Tabl e 1 . Secondar y alky l groups , bein g mor e stable , ar e mor e difficul tt o remov e fro m th e ring tha n tert-alkyl groups . Aci d catalyst s use d ar e th e phosphori c aci d o n Fuller' s earth , sulfuri c acid , o r oleu m an d aluminu m chloride . 3-tert-Butylpheno l i s prepare d b y direc thig h temperatur e (190°C) , reactio n of pheno l an d isobutene , an d b y isomerizatio n of

th e 2 - o r 4-isomer s o r mixtures .

H.W.B . REE

D Imperia l Chemica

l Industrie s Limite d Reviewe d b y GER D LESTO N Koppers Co. , Inc . S.H . Patinki n an d B_S . Friedma n in GA . Olah , ed. , FriedelCrafts and Related Reactions, Vol . 2 , Par

tI , Intererience Publishers , a divisio n o f Joh n Wile y & Sons , Inc. , Ne w York, 1964 , pp . 75-97 . R - Stro h an d co-workers in W . Foerst , ed. , NewerMethods of Preparative Organic Chemistry, Vol . 2 , Academi c Press , Inc. , Ne w York, 1963 , pp . 337-359 . M.W . Ranney , Antioxidants: Recent Developments, Noye e Dat a Corporation , Par k Ridge , NJ. , 1979 . Tabl e 1 . Propertie s an d Specification * of Importan tAlkylphenol s

Alkylpheno l 2-isopropyl-5-methyl-phenol ( thymol ) 4-(_r(-butylph_no l 5-methyl-2-(ert-butylpheno l 4-methyl-2*«ert-butylpheno i 2-phen y lpheno l 4-phenylpheno l 2,4-dimethyl-6-£e r r-butylpheno l 2.4-di-__r(.butylpheno l 2,6-di-fcrrbutylpheno l 4-octylpheno l 4,4'-i_opropylid_nedipheno l {bispheno l A ) 2,4-diniethyl-6-(lmethylcyclohexyl) - pheno l nonylpheno l 4-methyl-2,6-di-_er(-butylpheno l dodecylpheno l 2,2'thiobis(4-methyl-6--ertbutylphenol > 4,4'-thiobis(5-methyl-2-<er<-butylphenol ) 2,2'-methylenebi_<4-methyl-6-_?*-M>utyl phenol ) 2-methyl-4,6-di-«ert-nonylpheno l 2.2'*methylenebi_<4-methyl-6-( l methyl cyclohexyllphenol ) 4,4'-methylenebis(2,6-di-«erf-butylphen ol ) octadecy l 3-(3,5-di-«**-f-butyl-4 - hydroxyphenyl)propionat e l,l,3-tria<2-methyl-4-hydroxy-5-terr . butylphenylibutan e tris<3,5-d_-«_rt-butyl-4-hydroxybenzyl ) isocya n urat e 1.3.5-trimethyl-2,4,6-tri_<3,5-di-terf . butyl-4-hydroxyb_nzyl)benzen e pentaerythlity l tetraJu_(3-(3,5-di-e_r( - butyl-4-hydroxyphenyl)propionate ] Mp , ° C 50. 5 9 9 2 2 5 1 56-5 7 159-16 3 2 2 5 2 3 7 81-8 3 15 3

7 0

84-8 7 Ifi l 130-132. 5
13 0 15 5 49-5 4 18 3 22 1 24 4 110-12 5 Bp .

°C/kPa ° 231.8/101. 3 240/101. 3 244/101. 3 171/13. 3 241/101. 3 283-286 / 101. 3 250/101.3 . 174/13. 3 264/101.3 . 190/1.1. 3 253/101.3 . lfil/6. 7 280-302 / 101. 3 220/0.5 3 180/3. 0 295-320 / 101. 3 265/101.3 . 190/13. 3 322-335 • 101. 3

217.II.1 3 Solubilit y

Wate r inso l inso l s l sol '
s i so l inso l inso l inso l inso l inso l inso l inso l inso l
s l so l inso l inso l inso l inso l inso l inso l inso l inso l inso l inso l inso l inso l inso l Hydro carbon s
so l s l so l .so l
so l so l
s l so l so l
s l so l
so l slso l
s l so l
so l
s l so l
so l
s l so l
so l so l slso l
.so l inso l
so l
so l slso l
s l so l
s l so l
s l so l "T o conver tkP a to m m H g multipl y b y 7.50 . "Form s hydrat e CnH^O.jHjO , mp

, 37°C .

ALKY L PHOSPHATES . Se e Phosphori c acid s an d phosphates . ALKY L SULFATES . Se e Sulfuri c aci d an d sulfurou s esters . 

# € ALLANTOiN . Se e Uri c acid . ALLENE . Se e Hydrocarbons . ALLERGENS . Se e Industria l hygien e an d toxicology ; Anti-asthmati c agents . ALLITO L Se e Alcohols , polyhydric . ALLOSE , C 6 H , 2 0 6 . Se e Carbohydrates ; Sugar .

# Ullmann' s Encyclopedi a of Industrial Chemistr y

Volume s A1-A28 : alphabeticall y arrange darticle s Volume s B1-B8 : basi c knowledg e 

# U

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# c : Fift i Volui r Abra s Editoria l Advisor

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1
*• * Cresol s an d Xylenol s 2 5



# ovi'i'iuoriTE D Cresols an

d Xylenol s HELMU T FIEGE , Baye r AG , Leverkusen , Federa l Republi c o f German y 1 . Cresol s 2 5 1.1 . Physica l Propertie s 2 6 1.2 . Chemica l Propertie s 2 7 1.3 . Formatio n an d Isolatio n 2 8 1.3.1 . Isolatio n fro m Coa l Tar s 2 9 1.3.2 . Recover y fro m Spen tRefiner y Caustic s 3 0 1.4 . Productio n 3 1 1.4.1 . Alkal i Fusio n o f Toluencsulfonatc s .. . 3 1 1.4.2 . Alkalin e Chlorotoluen e Hydrolysi s .. . 3 2 1.4.3 . Cymen e Hydroperoxid e Cleavag e ... . 3 3 1.4.4 . Methylatio n o f

Pheno l 3 5 1.4.5 . OtherRoute s 38 1.5 . Separatio n o f

m - an d p-Creso l 4 1 1.5.1 . Physicochemica l Processe s 4 1 1.5.2 . Separatio n vi a Additio n Compound s . 4 2 1.5.3 . Separatio n vi a Este r o r Sal t Formatio n 4 3 1.5.4 . Separatio n b y Nuclea r Substitutio n .. . 4 3 1.6 . Qualit y Specification s an d Analysi s .. . 4 4


### 1 . Cresol s [i]-[3 ] Cresol , methylphenol , C 7 H 8 0 , M, 108.14 , occur s i n thre e isomeri c forms : 

## XcH , o-Cruo l 2-m«thylph«no l [93-48-7] 

# & v

m— Cresol p-Creso l 3-m«U_ylph«no l 4-m*U_7lpheno l [103-38-4]

[108-44-3] Mixture s o f

m - an d p-creso l an d o f

o- , m-, an d p-creso l ar e occasionall y referre d t o i n th e technica l literatur e a s dicreso l an d tri - o r isocre - sol , respectively . Cresylic acids [1319'77-3]

ar e mixture s o f

cre - sols , xylenols , highe ralkylate d phenols , an d pos - sibl y som e phenol . Taracids ar e cresyli c acid s obtaine d fro m tar . STADELB Rfirs tdiscovere d cresol i

n cow' s urin

e i n 185 1 [4] . FAIRLI

E an d WILLIAMSO

N foun d i ti n coal-ta r creosote 1.7 . Handling , Storage , an d Transportatio n 4 4 1.8 . Use s 4 5 1.9 . Economi c Aspect s 4 6 2 . Xylenol s 4 7 2.1 . Propertie s 4 7 2.2 . Isolatio n 4 7 2.3 . Separatio n 4 8 2.4 . Productio n 5 0 2.5 . Qualit y Specification s an d Analysi s .. . 5 1 2.6 . Handling , Storage , an d Transportatio n 5 2 2.7 . Use s 5 2 2.8 . Economi c Aspect s 5 2 3 . Environmenta l Protectio n 5 3 4 . Toxicolog y an d Occupationa l Healt h . . 5 3 5 . Reference s 5 4

i n 1854 . (The wor

d cresol , i n whic h "creosote " an

d "phe - nol " ar e combined , is partl

y explained b

y thi s fact. ) Creso

l wa s firs tsynthesized i

n 186 6 b y GRIESS , wh o boiled diazo - tize d toluidine . Al

l thre e cresol isomer

s wer e distinguished fo r the firs

ttim e b y ENGELHARO

T an d LATSCHINOF

T in 1869 . Cresols an

d cresol derivatives (ether s an d esters ) ar

e widel y distributed i

n nature . The

y ar e forme d as metabo - lites o f various microorganisms an d ur e foun d i n th e urin e o f mammals . Human

s eliminate , o n average , 8 7 m g o fpcresol pe r da y i n th e urin e [5] . Creso

l in it s various form

s is als o detectabl e in the extract s an d wate r vapo r distillate s o f man y plants , e.g. , i

n jasmin e flowe

r oil , cassi a flowe

r oil , caster lily oil , an

d ylang ylang oil , i

n the flora

l oi l o f Yucca gloriosa, in peppermint

, eucalyptus , an

d campho r oil , an d i n th e essentia l oil s o f severa l plant s o f the genus Artemisia, o f

conifers , o f

oa k wood , an

d o f sandalwood . Smal l amount s o f cresol ar e als o found in certai n food s an d drinks , e.g. , i

n tomatoe s an

d tomat o ketchup , cooke d as - paragus , certain types o f

cheese , butter oil , re

d wine , whis - ky , rum, cognac , an

d other brandie

s [6] , ra w an d roaste d coffee , blac

k tea , smoke d foods , an

d tobacc o and tobacc o smoke . Considerabl e amount s o f cresol ma y be forme

d an d enter surfac

e wate n i f forest s ar e pyrolyzed b

y pyroclasti c flo w fro m erupting volcanorfa s happened after th e erup - tio n o f MountSt . Helens in$98 0 (7) . Cresol s ar e important'chemica l ra w materi - als . The y wer e originall y dbtaine d onl y fro m coa lP.4 3 2 6 Cresol s an d Xylenol s Vol
. A 8 tar ; afte r WorldWa

r II , the y wer e als o obtaine d fro mspen t refiner y caustics . Sinc e the mid

1960s , the y hav e bee

n produce dsynthetically o n a n increasingly larg e scale . "Syntheti c cresol " no w provide s ca . 6

0 % o f the requirement s of

the Unite dStates , Europe , an dJapan ; only ca . 40 % o f th e requirement s are no w me t b y "natura l cresol, " i.e. , creso l fro

mcoa l ta r an dspen

t refiner y caustics .
1.1 . Physica l Propertie s [1]!_p*H11 ] A s pure substances , o- an dp-creso l ar e crystalline ; m-creso l i s aviscou s oil at roo mtem perature . Th e cresol s hav e aphenoli c odo r an d are colorless , but becom e yellow to brow n afte

r atime . Becaus e water

dissolve s freel

y i n cresols , they absor

b moisture fro

mthe-air . Physica l dat arelatin g t o th e cresol s hav e bee n compile din Table s 1 an d2 . Dat aconcern ing th e temperatur e dependenc e of their thermo

dynami c propertie s are foundin [8]-[ll] ; man y additiona l propertie s ar e containe di n [10] . Th e solubilit

y of th e cresol s i

n pheno l an di

n man y organi c solvents , e.g. , aliphati c alcohols , ethers , chloroform , an dglycerol , i s high . The y are les s solubl e i

n water than phenol . Th e pres enc e o f othe r water-solubl e organi c compound s (e.g. , methanol ) raise s their solubilit y i n water an dreduce s th e critical solutio n temperatur e [13] . Dissolve dinorgani c salt s lowe r th e wate r solubilit y of cresols .

Tabl e 1 . Physica l propertie s o f pur e cresol s Propert y o-Creso l m-Creso l /j-Creso l Mellin g poin ta t101. 3 kPa , " C Depressio n o f

nip b y I mol % o f

impurity , " C Boilin g poin ta

t101. 3 kPa , " C Densit y a t2 5 C ( s o r I). g/cm 3 at50°C(0 , g/cm 3 Viscosit y at50"C , mPa- s Refractiv e inde x a l 5 0 " C Dielectri c conslan l a l 5 0 " C Specifi c conductanc e a t5 0 °C , S/c m Surfac e tensio n a l SOT , N/ m Dissociatio n constan ta t2 5 " C Critica l temperature , " C Critia l pressure , MP a Critica l density , kg/m 3 Hea tcapacit y r a l 2 5 " C (g), J mol" ' K " ' c at25"C(i*or/) . .lmo|- | K - • c• 1 ,a l 50"C(/) , J mol" ' K." ' Enthalp y o f

fusio n AW

„ a tmp. 101. 3 kPa , kJ/mo l Enthalp y o f

sublimatio n __#,_

„ a l 2 5 "C , 101. 3 kPa , kJ/mo l Enthalp y o f

vaporizatio n A// „ a t2 5 "C , 101. 3 kPa , kJ/mo l <_/. „ athp, 101. 3 kPa . kJ/mo l Enthalp y o f

combustio n AW ° a l 2 5 "C , 101. 3 kPa , kJ/mo l Enthalp y o f

formatio n \H" ra l 2 5 " C (. v o r I), 101. 3 kPa , kJ/mo l M} at2 5 " C (g), 101. 3 kPa , kJ/mo l Fre e energ y o f

formatio n 6.G} at2 5 " C (. . o r I), 101. 3 kPa , kJ/mo l AC } at2 5 ° C (g). 101. 3 kPa , kJ/mo l Entrop y Sa t2 5 "C(s or/) . 101. 3 kPa , Jmol" ' K." 1 Entrop y S ° at25" C (g), 101. 3 kPa , JmoP ' K" 1 Cubi c expansio n coefficien ta t2 5 " C Solubilit y i n wate r a t2 5 "C , wt % at100°C , wt % o f wate r i n creso l at2 5 °C , wt % at10 0 °C , wt % Critica l solutio n temperatur e i n water , ° C at% cresol , wt % Vapo r densit y (ai r =1 ) j , Flas h poin t(close d cup) , " C .{J . Ignitio n temperature , " C V Flammabilit y limit , lower , i n ai r a t20**C , 101. 3 kPa , vol % s • 30.9 9 0.59 6 191.0 0 .„_ . 1.13 5 1.022 2 3.0 6 1.531 0 6.0 0 0.4 3 xlO' 1 0 34. 4 xlO" 6 4.8x10" " 424. 4 5.0 1 384 127. 3 154. 7 237. 9 15.83 0 76.0 7

- 45.22 2 -369 6

- 204. 8

- 128. 7 -55. 7 -33. 0 165. 5 352. 8 ' 2. 6 4. 8 13. 4 18. 4 164. 8 3 4 3.7 2 81 55 5 1. 3 12.2 2

0.74 9 202.2 3 1-.03Q 2 1.010 5 " 4.1 7 1.527 1 9.8 6 63. 4 xlO" 1 0 33. 4 xlO" 6 8.1x10-" * 432. 6 4.5 6 346 124. 6 225. 1 235. 0 10.71 4

- 61.7 6 47.42 9 -370 6

- 194. 2

- 132. 4 -59. 2 -40. 2 212. 7 356. 3 0.75 9 xlO" 3 2. 3 5.3 13. 1 20. 8 148. 6 3 6 3.7 2 86 55 5 1.0 34.6 9

0.91 5 201.9 4 1.15 4
• 1.011 6 4.4 8 1.526 9 10.1 8 60.2x10"' ° '34.0x10" " 5.4x10" " 431. 4 5.1 5 39 1 124. 6 150. 3 233. 3 12.71 5 73.9 8

- 47.58 1 -370 1

- 199. 5

- 125. 5 -51. 0 -31. 7 167. 4 351. 0 1. 9 4. 8 15. 8 24. 9 143. 7 34 3.7 2 86 55 5 1. 0Vol
. A 8 Vol
. A 8 Cresol s an d Xylenol s 2 7 i afte r icrcsols
. hav e bncem

tthermo

fl] ; man y ([10] . p i an di n ^alcohols , The y b e pres npound s Im wate r p'peratur e ith e wate r Tabl e 2 . Vapo r pressur e o f pur e cresols , for'/ ' 2. 260 ' C (i n kPa)[8].[12 ] Temp. , ** C 2 5 5 0 6 0 8 0 

### to o 120 140 16 0 18 0 20 0 22 0 26 0 30 0 34 0 38 0 o-Cresol ,

0.03 7 0.2 5 0.4 9 1.5 7 4.2 6 10.1 0 21.4 7 41.7 2 75.2 7 127. 6 204. 9 47 1 94 0 170 4 289 4 m-Cresol ,

0.01 9 0.1 2 0.2 5 0.8 6 2.5 2 6.3 6 14.2 6 29.0 1 54.4 5 95.5 2 158. 2 37 8 77 4 142 3 242 0 p-Cresol ,

0.01 6 0.1 1 0.2 3 0.8 3 2.4 7 6.2 9 14.2 1 29.0 7 54.7 5 96.2 4 159. 6 38 8 KK ) 152 1 265 9 an dreac t

wit h acy l anhydride s o r

acy l chloride s t o giv e th e correspondin g toly l esters , whic h are normall y referre dt o a s "cresyl " esters . Iso

cyanate s reac t

wit h th e O H grou p t o for

mure thanes . Substitutio n o

f the Hydroxy l Group . Unde r drasti c condition s (420 °C , A1 2 0 3 ) , th e O H group i s replace db

y ammonia , an dth e corre spondin g toluidin e i s obtained . If cresol s ar e reacte dwit

h sulfu r oxytetrafluorid e at

150°C , wit h diphenylphosphin e trichlorid e a t 22 0 °C , o r wit h phosphoru s tribromid e a t 28 0 °C , th e corre spondin g fluoro-, chloro- , o r bromotoluen e i s obtained . Butylthio l i

n hydrochlori c aci dre place s th e phenoli c O H grou p b y athiobuty l group . Distillatio n wit

h zinc powder

give s toluene .

["47.58 1 x —370 1 .-199. 5 •125. 5 £-51. 0 '-31. 7 •-.167. 4 £351. 0 Th e cresol s ca n b e distille dwit

h stea man d for mazeotrope s wit

h anumbe

r o f compounds , e.g. , decane , 1-decene , 1-undecene , dodecane , 1,2,4,5-tetrameth

y lbenzene , divinylbenzene , eth

ylen e glycol , diethylen e glycol methyl an dethy l ether , diethylen e glyco l diethy l ether , ethylen e glycol diacetate , benzyl formate , pheny l acetate , methyl benzoate , hexane-2,5-dione , 2-ocfanone , acetophenone , benzylamine , th e toluidincs , an d numerou s pyridin e derivatives . Vapor-liqui d equilibriu mdat aof

the cresol s wit

h numerou s other substance s ar e compile di n [14] ; thos e of m-cresol wit

h carbo n dioxid e an dnitroge n under pressur e a t 190-390° C ar e give

n i n [15 ] (2- 5 MPa ) an d[16

] (2-2 5 MPa) , respectively . 1.2 . Chemica l Propertie s [2] , [17 ] Acidity . Th e cresol s are chemicall y simila r to phenol . They are wea

k acid s an ddissolv e i

n aqueou s alkal i t o for

mwater-stabl e salt s know n a s cresolates . Therefore , they ca n be extracte d into sodiumhydroxid e solutio n fro msolvent s tha t ar e no t miscibl e wit

h water . Nevertheless , their acidit y i s s o lo w (pK^10.1-10.3 ) tha t

eve n hydrogen sulfid

e (pK a7.2) an dcarbo n dioxid e {pK. 6.4) are abl e t o liberate the mfro mcre solates . Thus , they hardl y dissolv e a t al l i n solu

tion s of sodiumcarbonat e o r

sodiumhydrogen carbonate . Etherificatio n an

dEsterification . Th e hy

droxy l grou p ca

n be etherifie d wit

h alky l halides , dialky l sulfates , an dtoluenesulfoni c aci desters . Hydrogenation . Hydrogenatio n in th e vapo r phas e a t 300-40 0 ° C unde r

pressure (u p t o 8 MPa ) i n th e presenc e of

catalyst s consistin g o f transitio n metal s an daluminu moxide give s toluen e (hydrodeoxygenation ) [18] . Hydrogeno

lysi s ove r catalyst s at-400.-50 0 ° C o r purely ther

mally a t 500-70 0 ° C ca

n bS*st>-cogtrolle

d tha t creso l i s mainly demethylate dt o pheno l (hydro

dealkylation ) [19] . Hydrogenatio n ove r Raney nickel o r noble-meta

l catalyst s unde r

les s sever e condition s give s methylcyclohexanol s o r methyl

cyclohexanones . Oxidation . Th e cresol s ar e sensitiv e t o oxida

tion . Dependin g o n th e oxidizin g agent , reactio n conditions , an dpositio n o f th e methy l group , oxidativ e reactions , which occur by fre e radical mechanisms , lea

dt o alarg e number

o f com pound s suc h a s hydroquinones , quinols , qui

nones , cyclic ketones , furans , dimeri c an dtri

meri c cresols , an dtoly l ethers . Strongly oxidiz

in g agent s brea

k dow n th e pheno l ring. Afte r th e hydroxy l grou p ha s bee n protecte d b y esterificatio n o r

etherification , th e methy l grou p ca n b e selectivel

y mono- , di- , o r

trichlori

nated , o r selectivel y oxidize dt o aformyl grou p (e.g. , wit h manganes e dioxid e o r

oxygen ) o r

t o a carboxy l grou p (wit

h aci dpermanganat e solu

tion) . Unlike th e othe r

tw o isomers , /?-cresol ca

n b e directly oxidize dwit

h oxyge n to giv e phydroxybenzaldehyde , e.g. , i n methanoli c so diumhydroxid e i

n th e presenc e o f

cobal t salt s [20] . Alkali fusio

n of th e cresol s i

n the presenc e of leaJrbxide o r

manganes e dioxid e produce s th e correspondin g hydroxybenzoi c acid s directly .tVol.A 8 Vol
. A 8 Cresol s an d Xylenol s 2 9

9 , [24 ]

I o n FR G 0.1 2 0.0 6 0.1 2 0.0 6 0.0 6 0.05 0.4 7 0.2 4 coa l [28] , [29] , oi

l shal e [30] , peat , woo d[31] , ligni n [32] , an dother

biomaluriuLs [33] . Th e yield s of

cresols , xylenols , an dothe r phe

nol s an dtheir

quantity rati o depen dnot onl y on th e startin g material , bu t

als o largel

y o n th e pro ces s condition s (especiall

y the temperature and th e residenc e time) , th e typ e of reactor , an dth e mod e of operation . Hydrogenatio n provide s the highes t yields , low-temperature carbonizatio n give s intermediate amounts , while high-tem

peratur e cokin g produce s the lowes t yield s (Ta

ble 3) . Smal l amount s of

cresols , xylenols , an dothe r pheno l derivative s ar e als o formedi n th e catalyt

i c an dtherma

l crackin g (especiall

y cokin g ther

ma l cracking ) of

petroleu mfraction s [34] . A t th e present

tim e cresol s an dxylenol s ar e isolate dfro

mcoa l tar s obtaine di

n the . high

temperatur e cokin g process , low-tcmpcruturc carbonization , an dLurgi pressur e gasificatio n o

f coa l (se c Tabl e 3) , an dfro

mspcnl refiner

y caus tics . 1.3.1 . Isolatio n fro

m Coa l Tars Th e main sourc e of

ta r cresol s i s the high

temperature coke-oven ta r (compositio n an d wor k u p - • Ta r an dPitch) , obtaine di

n the pro ductio n o f metallurgica

l cok e b y horizontal chamber cokin g of

bituminou s coa

l at 900

- 1300° C [23] . Thi s ta

r contains , on average , ca . 0.4-0. 6 wt % phenol , 0.8- 1 wt % cresols , an d 0.2-0. 5 wt % xylenols . I

n the Unite dKingdom , cresol s ar c als o produce dfro mlow-tcmpcrature coa l tar s obtaine di

n th e productio n of

smokeles s fuels (semicoke ) accordin g t o th e Coalite pro cess , wher e th e conten t

o f C 6 -C 8 phenol s i s ca . 1 0 time s higher . Another

sourc e of cresol s i s pro videdb y th e liqui dbyproduct s obtaine db y Saso l i n Sout h Afric ai n pressure gasificatio n o

f bitu

minou s coa

l b y th e Lurg i process , whic

h are sim

ila r in compositio n t o low-temperature tars . In addition , lignit

e tar s ar e use

di n th e German Democrati c Republic , Czechoslovakia , the Sovi

e t Union , an dIndi a[28] . Whe n the startin g produc t

i s high-lcmpera

tur e tar , th e phenol s ar e isolate db y extractio n wit h sodiumhydroxid e solutio n or , i n the Lurg i phenoraffin proces s (-*-*

• Ta r an dPitch) , fro

mth e carboli c oil tha t

boil s at 180-210°C , fro

mthe ligh t oil , an dfro

mth e filtrate of

th e naphthalen e oil ; wher e othe r coa l tar s ar e concerne dth e pro cedure s ar e similar . Th e hydrocarbon s an d pyridin e base s still present i n th e crud e phenolate causti c are remove db

y distillatio n wit

h steam . Th e crud e pheno l i s then se t fre e wit h carbo n dioxide . Frequently , th e phenolat e caustic s fro m cokin g plan t

effluents , whic h contai n primaril y pheno l andcreso l an donly ver y small amount s of xylenol s [35] , ar e incorporated . Th e composi

tio n o f the resultin g crud e pheno l may , therefore , var y extensively . Fo r

example , the compositio n o f crud e pheno l obtaine di

n thi s wa y fro mGer

ma n high-temperature coke-oven coa l ta r ma y b e a s follow s [27] : 1 5 % water , 3 0 % phenol , 1 2 % o-cresol , 18 % m-cresol , 12 % p-cresol , 8 % xyle

nols , an d5 % trimethylphenol s togethe r wit h highe r boilin g phenols . Afte r the alkal i conten t

o f th e crud e pheno l ha s bee n loweredfro

mca . 2 % t o ca . 0.3 % b

y scrubbin g wit

h water , th e crud e pheno l i s dehy

drate dazeotropicall y an drectifiedunde r vacu u minto the following fractions : phenol , o-cresol , w-/p-crcso l mixture , xylenol , an dpheno l tar . As the differenc e betwee

n th e boilin g point s o

fmandp-creso l i s ver

y smal l (0. 3 °C) , thes e compound s ar e obtaine da s asingle fraction , in whic h small amounts . o£_2.-6-xyleno l an d2-ethyl

pheno l ar e als o present . Th e ratia.of w-creso l t o p-creso l i s ca . 60:4 0 fo

r high-temperature tar

an d ca . 50:5 0 fo

r low-temperature tar . Example s of

firms tha t

isolate cresol s (an d xylenols ) fro

mcoa l ta r are th e Kopper s Co . an d th e Merictie

mCo i n th e Unite dStates , Coalit e & Chemica l Product s Ltd . an dth e Crod aSyn

theti c Chemical s Ltd . i

n th e Unite dKingdom , Riitgers-Werk

e AG an dChemische s Wer k Low i Gmb H i n th e Federal Republi c o f Germany , Cd F Chimi e i

n France , an dth e Nippo n Stee l Chemica l Co . i n Japan . Th e scale o n which cresol s an dxylenol s ar e recoveredfro

mcoa l ta r ha s decrease dcontinu

ousl y ove r th e pas t 2 5 year s fo r th e following primar y reasons : th e cok

e consumptio n of

the iron

- an dsteel-producin g industry , which chiefl y determine s th e suppl y o f

tar , ha s fallen ; processe s whic h lea dt o tar s wit

h lowe r creso l an dxyleno l content s are bein g increasingly usedi n cok e pro duction ; an dth e tar

outpu t fro mgaswork s ha s becom e insignifican

t du e t o th e changeover

to natura l gas . Th e situatio n ma

y change , however , becaus e blast-furnac e technolog y base do n th e us e o f high-temperature cok

e fro mbituminou s coa

l a s areducin g agent

wil l retai n a t leas t it s present importance , an dbecaus e th e gasificatio n of coa l t o prodac e syntheti c natura l ga s an dsyncrudeP.4 6 3 0 Cresol s an d Xylenol s wil l be expande d a s the price s o f oi l am i natura l ga s rise . Thi s woul dyiel

dmor e low-temperature tar , i n whic h the conten t

o f cresol s an dxylenol s i s much greate r

than i n high-temperatur e coke

ove n tar . 1.3.2 : Recover

y fro mSpen t Refiner y Caustic s I n th e Unite dStates , cresol s an dxylenol s ar e obtaine d TYiainl

y fro mth e naphth afraction s pro duce db y catalyti c an dtherma

l crackin g i

n the petroleu mindustry , whic

h contain , on the aver age , ca . 0. 1 % C 6 -C 8 phenol s [34] , [36] . I n th e scrubbin g of

th e sulfu r compound s containe di

n thes e fraction s (hydrogensulfides , alkyl

- an d arylthiols ) wit

h concentrate dalkalin e solutions , aproces s know n a s "sweetening, " th e aci d cresol s an dxylenol s are als o extracted . Th e com positio n o f

th e spent cresylat e caustic s fluctuate s widely , an dthey contai n o n th e averag e 20--25 % C

6 -C a phenol s an d10-15 % sulfu r compounds . Th e caustic s are collecte db y th e re processin g firms Merichem , Northwes t Petro

chemical , an dProductol , an dar e reprocesse di n central plant s b

y avariet y o f processes . A t th e Northwes t

Petrochemica

l i n Ana

cortes , Washington , th e thiol s i n th e alkalin e solutio n ar e first

oxidize dwit

h ai r to giv e disul

fides, which ar c the n decante da s a n oily laye

r [37] : ItSN- i + IfSN a + (1.

5 0 , + 11/ ) • KSSI f i 2 NaO H Th e phenol s ar e then precipitate dfro mth e aqueou s alkalin e phas e i

n apacke dcolum

n wit h acountercurren t

streamo f carbo n dioxid e (flue gas ) an ddecanted . Th e phenol s still presen t i n th e carbonate-hydroge n carbonat e phas e (2

- 6% ) are extracte dwit

h a n organi c solvent , fro

m which they ar e extracte dagai n wit h an aqueou s alkalin e phase , whic

h i s then returne dt o th e col

umn . A typical compositio n o f th e pheno l mix

ture obtaine di

n thi s wa y migh t be a s follows : 20 % phenol , 18 % o-cresol , 22 % m-cresol , 9 % p-cresol , 28 % xyleno l (al l si x isomer s plu s ethyl

phenol) , an d3 % higher

phenols . Thi s mixture i s then separate db

y distillatio n int o phenol , ocresol , w-/p-creso l mixture , an dxylenols , o r mix

ture s i n whic h particular

constituent s predomi

nate . Th e MerichemCo . of

Houston , Texas , i s th e bigges t processo r o f spent refiner y caustic s i

n th e Unite dStates , an dprecipitate s th e phenol s wit h Vol
. A 8 hydroge n sulfide , awast

e produc t o f the refine

rie s i n Houston [38] , [39] , insteado f usin g carbo n dioxide . Afte

r extractio n wit

h asolvent , th e sulfide solutio n obtaine di n thi s proces s i s concentrate di

n atriple-effect

evaporato r

to give sodiu msulfid

e fo r us e i n the pape r

industr y an d i n or e dressin g [39] . Th e wate r

vapo r condensat e forme

dat thi s stag e i s strippe dwit

h natura l ga s to remov e odo

rou s compounds , afte

r whic h i t i s passe dt o a coolin g tower . Th e natura l ga s i s then useda s a fue l i n th e final proces s ai r

incinerator . Befor

e bein g introduce dint o th e wast e ai r incinerator , whic h i s operate dat

ca . 1370 C C , the proces s ai r fro mal l of th e othe r

part s o f th e plan t

i s scrubbe dwit

h alkalin e solution . I

n addition , odor-neutralizin g chemical s ar e spraye dalong

sid e th e plan t

area . Al l of th e water a t th e plan t (includin g rai n water) i s recycledi n a n integrate d system . Wate r

i s release dint o th e environmen t almos t completel y a s water

vapo r fro mth e cool

ing tower s [39] , [40] . Accordin g t o th e proces s operate dunti l 197 1 b y th e Pittsburg h Consolidate dChemica l Co . [41] , [42] , th e spen t refiner y caustic s werejreate d directl y wit h flu e ga s contain

in g 8-14 % carbo n dioxide.'Fro mth e crud e pheno l thu s precipitated , afractio n boilin g a t 100-23 5 ° C wa s remove d b y distillatio n an dextracte dcontinuousl y i n acounter curren t o f aqueou s methanol-ligh t naphtha . After

re mova l o f th e final thio l an dbas e residue s wit h a n ion

exchang e resin , th e cresyli c acid s tha t ha dentere dth e aqueou s methanoli c phas e wer e recovere db

y fractiona l distillation . I n 1984 , th e "cresylics " capacitie s of Meri

chem , Northwest , an dProducto l wer e 5 5 000 . 1 5 000 , an d1000 0 t/a , respectively [43] . Howev

er , thes e figure s include phenol , the xylenols , an d severa l othe r alkylphenols . I

n addition , Meri

che mn o longer

isolate s cresylic s exclusivel y fro mspent refiner y caustics , bu t

als o work s u

p crud e phenol s fro

mcoa l tar s o f variou s types . Th e recover

y of cresol s an dxylenol s from spent refiner y caustic s ha s s o fa

r bee n confine d to th e Unite dStates . Becaus e differen t refiner y technique s ar e usedi

n the Federal Republi c o f Germany , the ' productio n of cresol-containin g spent caustic s i s insufficien

t fo r economica

l re processing ; o r

n o spent caustic s ar e produce dat al l becaus e desulfurizatio n i s carrie dou t differ

ently , e.g. , b

y hydrotreating . I

n th e Unite dState s a s well , th e recover

y of creso l fro mspent refiner y caustic s i s stagnatin g o r

eve n recedin g becaus e thi£refinerie s ar e likewis e changin g ove r eithe r t o hydrptreatin g o r

to UOP' s Mero x process , partl y becaus e th e pric e of

sodiu mhydroxid e ha s risenP.4 7 

# T

• Vol
. A 8 ver y sharpl y i

n recent years . Wit

h th e Mero x process , substantia l quantitie s of cresol s remai n i n th e gasoline , an dconsiderabl y smalle r amount s o f

spen t caustic s ar e obtained . 1.4 . Productio n Sinc e 1965 , whe

n th e recover

y of cresol s fro

m coa l tar an dspent

refiner y caustic s ha dbecome insufficien t t o meet th e risin g demand , thes e compound s hav e bee

n increasingl y produce db y synthesis . Th e processe s no w in us e ar e

- alkal i fusion of

toluenesulfonate s

- alkalin e chlorotoluen e hydrolysi s

- splittin g of

cymene hydroperoxid e

- methylatio n o f

pheno l i n th e vapo r

o r liqui d phas e Th e first thre e processe s star t

fromtoluen e an dwer e develope dfro mth e correspondin g benzene-pheno l synthese s (-< • Phenol) ; t o som

e exten t they ar e eve

n carrie dou t

in converte d plant s tha t

formerly produce dphenol . I n th e fol

- lowing descriptions , attentio n wil l b e primaril y pai dt o th e difference s betwee n thes e processes . The methylatio n o f

pheno l i s aproces s specifi

- call y develope dto produc e cresol s an dxylenols . Eac h proces s give s adifferent isomer distribu

- tion , an dal l are , therefore , o f individual impor

- tance . 1.4.1 . Alkal i Fusio n o f

Toluenesulfonate s [44] , [45 ] Th e alkal i fusion i s usedmainl y t o manufac

- ture p-cresgLan d consist s o f four reactio n steps : 2CH,-C,H , + 2H.SO .

•= i 2 CH,-C < H 4 -S0 J H + 2 H, 0 (1 ) 2 CHJ-C.H.-SOJ H + Na,SO ,

— . 2 CH,-C,H.-SO,N a + H, 0 + SO , (2 ) 2CH ) -C,H.-S0,Na-i-4Na0 H

— . 2CH J -C,H«-ON a + 2Na,SO , + 2 H. O (3) 2 CHj-C.H.-ON a + SO , + H, 0

—.2CH 1 -C < H < -OH* f

Na,SO , (4) 2 CH.-C.H , + 2 H,S0 4 + 4 NaOH

— . 2 CH.-C.H.-O H + 2 Na.SO , + 4 H, 0 Th e sulfonatio n o f

toluen e (1 ) i s normall y carrie dou t

wit h concentrate dsulfuri c aci da t 120-13 0 ° C an datmospheri c pressure . T o en - sur e tha t substantiall y all o f

th e sulfuri c aci dha s Cresol s an d Xylenol s 3 1

bee n reacted , th e wate r

o f th e reactio n i s en - traine dwit

h exces s toluen e vapor . Th e sulfoni c aci dmixture i s neutralize dwit h sodiu msulfit

e (and/o r sodiu mhydroxide ) (2 ) an dthe n fuse d wit h exces s sodiu mhydroxid e a t 330-35 0 ° C (3) . Th e mel t i s introduce dint o water , th e sodiu m sulfit e filtere doff

, an dth e aqueou s phas e acidi

- fiedwit h sulfu r dioxid e fro

mreactio n ste

p (2) and/o r wit h sulfuri c • aci d(4) . Thi s give s a n aqueou s phas e containin g sodiu msulfite , whic h i s returne dt o th e neutralizatio n uni t (2) , an da crud e creso l phase , which i s dehydrate dby azeo - tropi c distillation . Th e plan t an dproces s ar e sim

- ila r to thos e formerl y use din th e synthesi s o f pheno l b y alkal i fusio n of

sodiu mbenzenesul

- fonate . Th e dehydrate dcrud e creso l phas e i s sep - arate dby fractiona l distillatio n int o phenol , o - cresoi , m-/p-creso l mixture , an daresidu e con - tainin g ditoly l sulfones , xylenols , higher phenols , an dothe r compounds . Th e ditoly l sulfone s are forme din th e sulfonation ; the phenol s an dxyle

- nol s ar e forme di n smal l quantitie s i n th e alkal i fusion [46] , [47] . See [46] for th e mechanis mo f th e fusion reaction . Th e distributio n o f

th e creso l isomer s de

- pend s mainly o n th e sulfonatio n conditions . Normall y amixtur e o f

th e followin g composi

- tio n i s obtained : 6-12 % o-cresol , 6-12 % mcresol , 80-85% o p-creso l [44] , [48] . Afte r the ocreso l ha s bee

n remove db

y distillation , a p-creso l of

ca . 9 0 % purity ca

n b e obtaine db

y distillation . Fro mthis , p-creso l wit h am-creso l conten t o f onl y ca . 1 % can b e isolate drelatively easily b y melt crystallizatio n (see p . 41) . A creso l yieldo f

80% , base do n toluene , i s possibl e [48] . Th e yiel dfall s a s th e m-creso l con - ten t o f th e creso l mixtur e increase s [44] , [47] . Unde r kineticall y controlle d(mild ) sulfona

- tio n condition s an dmil dalkal i fusion , i t i s pos - sibl e t o produc e creso l mixture s wit h a n eve n smaller conten t o f m-cresol . I t

ha s bee n claime d tha t sulfonatio n wit

h chlorosulfuri c aci da t 33-4 5 ° C give s aproduc t

fre e fro mm-creso l a t

a yieldof 90 % (calculate do n th e basi s of toluene ) an dwit h an o-/p-creso l rati o o f

15:8 5 [49] . Th e sulfonatio n o f

toluen e wit

h sulfu r trioxid e - sulfu r dioxid e mixture s a t

25-50° C likewis e lead s t o toluenesulfoni c acid , mixture s almos t devoi do f th e m-creso l isomejr

, an dwhic h hav e a

n o-/p-isomer

ratio a s lo w a4J3:9 7 [50] . I n th e ab

- senc e o f asulfu r dioxid e solvent , i t

ma y eve n be possibl e t o obtai n a n o - an dm-isomer conten t o f onl y 0.5 % when th e processe s carrie dou t i n a loo p reacto r

at 0°C , an dwhe

n gaseou s S0 3 , di

-P.4 8 3 2 Cresol s an d Xylenol s Vol
. A 8



# VS? lute dwit h a n iner t gas , i s introduce dint o th e reacto r a t severa l location s [51] . Th e iner t ga s (wast e gas ) i s no t

necessar y i f th e proces s i s car riedou t under vacuum[52] . Thermodynamicall y controlle dsulfonatio n condition s (high temperature , lon g reactio n time , an dth e us e of

asulfonatio n mixture wit h a lo w water content ) lea

dt o a n equilibriu mcon tainin g ca . 5 % o-, 54 % m-, an d41 % p toluenesulfoni c aci d[53] . Alkali fusio n o f suc h

- mixture s then give s a

n isome r distributio n of

ca . „'5 % o-cresol , 56 % m-cresol , an d39 % p-creso l [47] . Technical-grad e m-creso l ca n als o be pro duce db y toluen e sulfonatio n accordin g t o apro ces s use d b y ihc Honsh

u Chemica

l Industr y Co . [54] . Stea mat 165° C i s introduce dint o a n tolu

enesulfoni c aci dmixture rich i n m-isomer

ob

taine dunder

thermodynamicall y controlle dcon dition s a s describe dabov e (isomerizatio n fo r severa l hour s at 190-200°C) , whereupo n o- an d p-toluenesulfoni c aci dar e hydrolyze dback to sulfuri c aci dan dtoluene . Th e toluen e i s distille d wit h the steam ; m-toluenesulfoni c aci dwit h a purit y abov e 90 % remains , togethe r wit h sulfu

ric acid . Sid

e reaction s durin g the isomerizatio n an dhydrolysi s ca

n b e suppresse db

y addin g so diu msulfat

e (5-1 0 mol% , calculate do n th e basi s of sulfuri c acid ) to the sulfonatio n batch . I n thi s way , remova

l of th e sulfuri c aci dtha t

i s forme di n th e hydrolysi s a s alowe r phas e a t ca . 140-15 0 ° C i s als o possibl e [55] . It i s als o possi

ble t o neutraliz e the hydrolysi s mixture wit h con centrate dsodiumhydroxid e solution , filler of f th e resultin g sodiumsulfat e a t 80 "C . introduc e th e solutio n o

f sodium...-tolucncsulfonat c int o asodiumhydroxid e melt , containin g 10-15 % potassiu mhydroxid e to facilitat e stirring , a

t a n initia l temperatur e of

33 0 °C , an dt o fuse i

t at 34 0 °C . Th e distillatio n of

th e crud e creso l phas e ob

taine dafte

r acidificatio n give s m-creso l wit h a purity of u p to 9 8 % i

n ayieldof

ca . 6 5 % , calcu

late don the basi s of

reacte dtoluen e [55] . p-Creso l i s produce daccordin g to th e tolu

en e sulfonatio n proces s b y SheVwtp-Williams , (capacit y 1 5 00 0 t/a ) i n th e Unite dStates , b

y Crod aSyntheti c Chemical s Ltd . (capacit y 1200 0 t/a ; sulfonatin g agen t i s S0 3 ) i

n th e Unite dKingdom , an di

n Japa n (ca . 500

0 t/a) . m-Creso l i s produce di

n thi s wa y b y th e Honsh u Chemica l Industr y Co . (ca . 240

0 t/a) . A plan t designe dt o operat e th e Honshu proces s als o reporte dto be capabl e of producin g 3000

- 500 0 t/ aof m-creso l ha s bee

n buil t i n Indi ab y Gujarat Aromatics . Th e toluenesulfoni c acid-creso l proces s i s relatively simpl e a s regard s th e plan t required . It s primar y drawbac k

i s th e unavoidabl e formatio n of sodiu msulfit

e i n aqueou s solution . A

t Crod a Syntheti c Chemicals , th e sodiu msulfit e i s up grade dint o aproduc t

suitabl e fo

r th e pape r

in

dustr y [56] . At Sherwin-Williams , sodiu msul

fite i s oxidize dwit

h ai r to for msodiu msulfat

e [57] , bu t p-creso l i s still presen t

in th e aqueou s sulfit e solutio n (3000-500 0 ppm) ; t o avoi d stripping , thereb y causin g a n odo r proble mi

n th e neighborhoo dof

th e plant , th e solutio n i s first passe dthroug h column s o f activate dcarbo n to adsor b th e cresol . Th e activate dcarbo n i s re generate dever

y 2 4 h wit h 10 % sodiu mhy

droxid e solution . Th e amoun t of p-creso l recov ere di n thi s wa y i s sufficien

t t o pa y fo r th e addi

tional installation s [58] . 1.4.2 . Alkalin e Chlorotoluene Hydrolysi s Th e hydrolysi s proces s i s importan t i n the productio n of

cresol-wit

h ahig h m-creso l con tent , an di s usedi

n th e FederalRepubli c of

Ger

man y b y Baye r AG , the world' s larges t

manufac

ture r o f syntheti c cresol s (capacit y more than 3000 0 t/a) . I n th e first reactio n step , amixtur e of o- an d p-chlorotoluen e i

n a1: 1 rati o i s produce db y chlorinatin g 1 mol of

toluen e wit

h 1 mol of chlorin e i n th e presenc e of

iron(III ) chlorid e an d disulfu r dichlorid e (- + Chlorinate dHydrocar

bons) . CH,-C,H , + Cl , •--. . CH j C.H.-C I + HC

l I n th e nex t reactio n step , thi s mixture i s hy

drolyze dwit

h exces s sodiu mhydroxid e solu

tio n (2.5-3. 5 mol/mol ) at

360-390° C an d280

- 30 0 ba r (28-3 0 MPa ) [59] . CH,-C 6 H 4 -C1 + 2NaOH

— . CH,-C t H 4 -0N a+ H, 0 + NaC l Th e exothermi c reactio n i s carrie dou t con tinuousl y in high-pressure tube s severa l hundre d meter s long ; th e tube s ar e mad e of nickel steel t o withstan dth e corrosiv e actio n o f th e reactio n mixture . Separatio n o f

th e components , whic h ar e introduce dvi aamixin g chamber , i s pre vented'b y causin g th e reactio n mas s to flo w a t high Telocity , wit

h frequent change s i n th e direc

tio n of

r How ; finally, th e reactio n mixture i s homogeneous .P.4 9 Vol
. A 8 Cresol s an d Xylenol s 3 3

fishyTjolu

1280 -

S+NiC I Th e creso l i n th e resultin g sodiu mcresolat e solutio n i s se

t fre e b y neutralization ; fo

r thi s pur - pos e th e hydrochlori c aci dformeddurin g chlori

- natio n can als o be used . Th e coproduc t sodiu m chlorid e can b e returne dt o th e chlor-alkal i elec

- trolysis . Fo r economi c reasons , i

t i s importan t

tha t th e startin g material s ar e produce dat location s sufficientl y clos e to on e anothe r

tha t conveyanc e throug h pipeline s i s possible . Th e technolog y of th e proces s largely correspond s t o tha t o f th e Dow-Baye r

chlorobenzene-pheno l hydrolysi s proces s [60] . I

n th e manufactur e of

cresols , how

- ever , th e amount s of

th e byproduct s forme dar e larger than i n thi s process : thes e include ditoly l ether s [bis(mcthylphenyl ) ethers] , i n particular , tolylcresol s [methyl(methylphenyl)phenols] , an d small amount s of

toluene , phenol , benzoi c acid , an doff-ga s fro

mcrackin g (methan e an dhydro

- gen) . Th e remova

l o f smal l amount s of

pheno l b y azeotropi c distillation , e.g. , wit h chlorotoluene , i s deal t wit h i n [61] . Wherea s i t

i s hardl y possibl e t o contro l th e scal e o n which tolylcreso l i s formed , th e forma

- tio n of ditoly l ethe r

ca n b e controlle dvi ath e temperature , th e residenc e time , an dth e sodiu m hydroxid e concentration ; i n addition , th e scal e on which thi s byproduc t

i s formedca

n b e min

- imize dby recycling . Thi s possibilit y arise s fro

m the fac t that ditoly l ether s ar e hydrolyzabl c - thoug h les s easil

y than th e homologou s di

- pheny l ether . Therefore , i f the reactio n i s opti

- mall y controlled , yield s of

ca . 80% , base don chlorotoluene , ar e attainable . However , ditoly l ethe r ha s severa

l uses , e.g. , a s aheat

transfe r medium(Diphy l DT) , a s a n electrica

l insulan t (Baylectro l 4800 ; replacement fo r polychlori

- nate dbiphenyl) , an da s aprecurso r fo r tannin g agents . Therefore , ditoly l ether i s n o longer

re - cycled ; indeed , the condition s ma y be adjuste dt o increas e th e selectivit

y fo r thi s compound . Th e proces s give s ver

y pure cresols , i.e. , product s tha t

are almos t

fre e fro mothe r com - pounds . Th e o- , m- , an dp-isomer s ar e presen t i n arati o of ca . 1:2:1 . Thi s rati o differs fro mtha t of th e chlorotoluen e inpu t

becaus e isomerizatio n vi aaryn e intermediate s i s assume dt o occu r [62] , [63 ] unde r

th e sever e condition s of

hydrolysis . Afte r th e o-creso l ha s bee

n distilled , am-jpcreso l mixtur e containin g ca . 70 % m-creso l i s obtained . Th e plan t ca n als o be operate do n pur e o- o r p-chlorotoluene . Th e hydrolysi s of p-chloro

- toluen e the n give s a1: 1 m-/p-creso l mixture , an d hydrolysi s o f o-chlorotoluen e give s a1: 1 o-\mcreso l mixture . Technicall y pur e m-creso l i s ob

tainabl e fro

mth e latte r

b y distillin g of

f th e ocresol . Hydrolysi s o f

chlorotoluen e withou tsubstantia l isom - crizalio n i s possibl e unde rmilde rcondition s (200-350°C ) wit h alkal i hydroxid e [63] , [64] , alkal i carbonate s [65] , o r ammoniu m hydroxid e [66] , o r wit h alkal i acetat e o r alkal i propionat e solutio n [67 ] i n th e presenc e o f coppe ro r cop - pe rcompounds . Thes e processe s ar e no tuse d industrially . 1.4.3 . Cymen

e Hydroperoxid e Cleavag e Th e synthesi s vi acymene hydroperoxide , whic h i s als o know n a s th e cymene-creso l pro - cess , permit s the productio n of in- o r p-crcso l fro mth e correspondin g cymene s (isopropyltol

- uenes) . I t i s unsuitabl e fo

r th e productio n of

ocrcsol . The proces s consist s o f thre e reactio n steps : 1 ) Toluen e propylatio n an d cymen e isomerizatio n CH 3
, i ao-e o o c + CH,=CH-CH , > • s ^ AltVH Q CH .

CH 3 

# 3' / •CH o-Cymen e I VCH
_ C

H / \ H3 C Ctt , ^ CH

, 

### 1 

### /»* CH . m— Cymene 2 ) Oxidatio n o f

cymen e t o cymen e hydroperoxid e Cll 3 CH , + 0 , / C H (Air ) 'CH 3 3 ) Peroxid e cleavag e CH 3 (Alk-li )

CH . ICH , C-OO H X CH , o n + CHg-CO-CH j O H m/p-Creso l B y compariso n wit

h the analogou s Hoc

k cumen e proces s (- > Acetone) , the cymene - cresol proces s ha s alowe

r space-tim e yield , in

- volve s considerabl

y mor e costl y distillatio n proce - dures , necessitate s mor

e extensiv e treatment

o f wastewater , andgive s ajfroduc t yiel dtha t i s 20-30 % lower . The reasons-for thi s ar e a s fol

lows : i p— Cymene *•_ .P.5 0 3 4 Cresol s an d Xylenol s Vol
. A 8 1 ) Al l thre e isomers , o-, m-, an dp-cymene , ar e forme di

n the propylatio n o

f toluene . O

f th e thre e isomers , o-cymen

e no t only i s hardl y oxi

dize dbu t als o increasingly inhibit s oxidatio n of th e othe r cymene s [68 ] a s it s concentratio n i n th e isome r mixture rises . Fo r

continuou s oxidation , th e o-cymene conten t

of the cymene mixture mus t b e kep t belo w 10 % a t

all time s [69] , [70] . Thus , cymene mixture s are neede dtha t contai n a s littl e o-cymen

e a s possible . Th e lowts t

w-cymcn e conten t i s that o f a cymene mixture i

n thermodynami c equilibriu m [70] , [71] . Aluminu mchlorid e mus t b e use dto reac h thi s equilibriu ma s quickly a s possibl e [72]-[74] . Th e isomer

ratio obtainabl e wit

h alu

minumchlorid e unde r

practical condition s i s ca . 3 % o- , 6 4 % m- , an d3 3 % p-cymene . As the o cymen e concentratio n rise s while th e oxidatio n i s i n progress , alarg e amoun t o f th e cymene mus t b e returne dt o th e first

stag e of th e proces s afte

r th e cymen e hydroperoxid e an dothe r byproduct s hav e bee n separated , s o tha t

th e o-cymene con ten t ca n agai n be lowere dt o ca . 3 % throug h isomerizatio n on aluminu mchloride . Th e diiso

propyltolucnc s formeda s byproduct s i n th e alkylatio n an dseparate db y distillatio n are als o returne dt o thi s isomerizatio n step . 2 ) Th e oxidatio n rate s of

th e cymene s are lowe r tha n tha t

o f cumene . I

n addition , th e cymene s ca

n be oxidize du

p t o aperoxid e con ten t o f only ca . 20% , wherea s oxidatio n level s exceedin g 30 % ar c possibl e wit h cumene . Th e proportio n of

unreacte dcymene that

mus t b e distille dan dreturne dt o th e reactio n is , there

fore , greate r

than i n th e cumene-pheno l pro cess . At higher degree s of

oxidation , th e forma

tio n of byproduct s fro

mexcessive oxidatio n o

f th e isopropy l grou p t o dimethyl(tolyl)methano l an dmethylacetophenon e i s greatl y increased . 3 ) Th e methy l grou p o

f th e cymene s i s like

wis e oxidized ; fo

r detail s o f th e mechanis mof p-cymen e oxidation , se

e [75] . Th e rati o at

whic h th e methy l grou p an disopropy l grou p ar e sub

jecte dt o oxidativ e attac k ma y be a s hig

h a s 1: 4 [76] . A s th e primar

y peroxid e i s les s stabl e than th e tertiary peroxide , i

t i s more easily converte d int o secondar

y product s (isopropylbenzy l alco

hol , isopropylbenzaldehyde , cumini c acid) . A more importan t

drawbac k

i s tha t i n the highl

y exothermi c aci dcleavage , i n additio n t o isopro

pylphcnol , 1 mol o f

formaldehyd e i s formedpe r mol e of primar y peroxid e still present ; becaus e formaldehyd e i s abl e to bindu p l o 2 mol of cre so l a s aformaldehyd e resin , th e creso l yieldi s substantiall y diminished . Moreover , th e pres enc e of resin make s th e produc t

more difficul

t t o wor k up . Variou s solution s t o th e proble mhav e bee n proposed : (1 ) selective decompositio n of th e primary peroxid e durin g th e actua l oxidatio n b y addin g catalyti c amount s o f picoline , pyrrole , thiophen e [77] , o r

triphenylphosphin e [78] ; (2) selectiv e hydrogenatio n of th e primary peroxid e ove r anoble-metal catalys t

[79] after th e oxida

tio n i n aseparat e stag e o

f th e proces s (befor

e th e aci dcleavage ) o r

decompositio n b

y passin g th e primary peroxid e ove

r amagnesiu maluminat e catalys t [80 ] o r treatmen t wit h sodiu mhydroxid e an dheavy metal s [81] ; (3 ) extractio n o f th e pri

mary peroxid e [82]—[85] . However , i t i s simpler t o dissolv e th e product s resultin g fro mmethy l grou p oxidatio n continuousl y an da s full y a s possibl e i n exces s alkal i solutio n presen t durin g th e actua l oxidatio n itself [68] , [69] , [86] . Th e organi c acid s presen t

i n th e spent

caustic s (ca . 0. 5 k g of cumini c acid , tolui c acid , phthali c acid . an dothe r product s pe r

kilogra mo f cresol ) ar e largely precipitate ddurin g th e acidificatio n an d ca n b e remove db

y filtration . Additiona l removal fro

mth e filtrate.(wastewater) i s possibl e b y extractio n [87] . " " "" • - Accordin g t o anothe r

suggestion , hydroge n peroxid e shoul db e presen t

durin g cleavag e o f

cymen e hydroper

oxid e l o creso l [88] ; alternatively , this cleavag e coul db e effecte dunde r

mildl y hydrogenatin g condition s [89] . Thes e measure s decreas e th e exten t of yield-lowerin g sid e reac tion s undergon e eithe r

b y th e primary peroxid e o r b y it s secondar y product , formaldehyde . 4) Th e reactio n mixture afte r acidi c peroxid e cleavag e contain s no t

onl y cresol , acetone , an d unreacte dcymene , bu t

als o isopropenyltoluene , 2-tolylpropanol , isopropylbenzy l alcohol , iso

propylbenzaldehyde , methylacetophenone , iso

propylphenol , an dnumerou s othe r compounds . Th e separatio n of

thes e byproduct s i s relativel y expensiv e becaus e o

f thei r larg e number , thei r simila r boilin g points , an dth e formatio n of azeotropi c mixture s [90] . Cymene-creso l plants , i

n which cymen e mix

ture s ar e use dan dwhic

h hav e anameplat e ca pacit y of 2 0 00 0 t/ aeach , hav e been operate di n Japa n b y Mitsu i an dSumitom o sinc e 1969 . Th e produc t ha s am - an dp-creso l conten t

of more tha n 99.5% o an dam-/p-rati o o f 60:40 . Th e aceton e coproduc t

i s of hig h quality [91] . Ufour e p - o r /;i-cymene i s used , th e high cos t o f recyclin g an disomerizatio n necessitate dby th e presenc e of

o-cymen e i s eliminated , an dpur e p - o r to-cresol ca

n be obtaine ddirectly . Fo r ex -P.5 1

Vol
. A 8 Cresol s an d Xylenol s 3 5 ample , unti l 1972 th e Hercule s Powder Co . oper - ate daplan t

a t Gibbstow n i

n th e Unite dState s fo r the manufactur e of

p-creso l fro

mp-cymen e obtaine dfro

mnatura l terpene s [92] . Owin g to th e clos e proximit

y o f the boil

- in g point s of

th e cymen e isomer s (m-cymen e 175. 1 'C , p-cymen e 177. 1 ''C , o-cymcnc 178. 3 "C , a t 101. 3 kPa) , the m-cymene , at most , ma y possi

- bl y b e isolate dat

reasonabl e cos t

fro mth e cymen e mixture resultin g fro

mth e propylatio n of toluen e (se

e above ) [74] . However , bot h pur e m-cymen e an dpur e p-cymen e ca n be isolate d accordin g to UOP' s Cyme x proces s on p - cymcnc-sclcctiv c 13

X molecula

r sieve s b y using toluen e a s desorptio n agen t [93] . Th e pro - ces s correspond s t o UOP' s Pare x proces s fo r ih c isolatio n of

p-xylen e fro

mC 8 aromatic s (-•Xylene) . A cymene-creso l plant , basedon th e UO P an dHercule s Powde r technologies , fo

r the manufactur e of

pure m-creso l an dp-creso l [fo r th e antioxidan t

2,6-di-.e//-butyl-4-methyl

- pheno l (BHT) ] i s bein g constructe di n Chin a [94] . I f i n th e Cyme

x proces s onl y on e isomer , e.g., . p-cymene , i s required , th e m-/o-cymen e mixture leavin g th e adsorptio n column , whic h i s impov

- erishe dwit

h regar dt o p-cymene , ca

n be re - isomerize dan dreturne dt o th e separato r [95] . Sinc e i t i s les s importan t

i n thi s cas e t o hav e th e lowes t possibl e o-cymene content , th e isomeriza

- tio n (an dth e alkylation ) can , fo r example , be carrie dou t

o n phosphori c acid-aluminu moxide catalyst s at

37 0 ° C instea dof

usin g aluminu m chlorid e [95] . I n th e manufactur e o f

**i-cresol , •n-cymene can als o b e obtaine db y selectiv e crackin g o f th e p-cymen e presen t

i n cymen e mixture s wit

h alow orlh o isome r

content . Cleav

- ag e o f p -cymene (an dt o alesse r exten t lha l o f o-cymcnc ) t o toluen e an dpropylen e i s accomplishe da l 300-40 0 " C o n shape-selectiv e ZSM5 zeolite s [96 ] tha t ar e particularl y selectiv e i n th e MgO-modifie dI__T-ZSM5 for m[97] . A further , technicall y les s attractiv e wa y o f isolatin g rncymen e consist s i

n complexin g with anhydrou s hydro

fluori c acid-boro n trifluorid e a t temperature s belo w

- 4 0 ; C [98] . 1.4.4 . Methylatio n of

Pheno l Syntheti c cresol , especiall y o-cresol , an dxyle

- no l ar e no w produce dlargel y by methylatio n o f pheno l wit

h methano l i

n th e presenc e of

cata - lysts . 2.6-Xyleno l i s produce dalmos t entirel y b y thi s method . Th e proces s consist s o f

onl y on e reactio n step , bu t i s base do n phenol , whic h i s relatively expensive ; th e separatio n of product s fro

mth e reactio n mixtur e i s als o costly . Thi s i s partl y be

- caus e th e boilin g point s o f severa l component s are ver y near on e another , an dpartl y becaus e i n som e case s th e purit

y of th e produc t

mus t mee t ver y stric t requirements . Th e reactio n ca

n b e carrie dou t

either i n th e vapo r phas e o r i n the liqui dphase . Methylatio

n i n th e Vapo r Phase . Currentl y vapor-phas c methylatio n i s use dexclusivel y to manufactur e pur e o-creso l and/o r pur e 2,6

- xylenol : O H 

# 6
• CHjO H O H

O H CH

3 + HJJ O

A * tf 2 M = -10 4 kJ/mo l

. CHjO H H3C N -jk v ^CH 3



### \S Hj O

A#»
_ Sid e reactions : CH 3 0 H — - . C O + Hj O - C O + 3 H 2 - C

O + 2 H 2 A/f ^ —"*" • CO g + H g tmH^gm = -4 8 kJ/mo l -9 1 kJ/mo l -4 1 kJ / mo l CH « + Hj O itH^ ***

* -20 6 kJ/mo l A t atmospheri c o r

slightl y elevate dpressure , asuperheate dmixture o f

th e vapor s of

phenol , methanol , an dwater

i s passe dat

aliqui dhourl y spac e velocit

y (LHSV ) o f

1- 2 h" ' ove

r ametal oxide catalys t

fixedi n amultitubular

reacto r o f stainles s steel at

atemperatur e of

300-46 0 ° C [99]-[101] . Th e reactio n temperatur e require d depend s o n th e natur e o f

th e catalys t

an do n th e desire dcompositio n of

th e product . Th e temper - atur e i s permitte dt o deviat e fro mthi s leve

l b y only afe w degrees . Th e heat of th e reactio n i s dissipate dby boil

- ing organi c hea t

transfe r medi a[102] , b

y circu

- latin g sal t melt s [100] , o r

throug h th e generatio n of high-pressure stea

m[101] . Th e sligh

t los s of catalyti c activit

y tha t occur s in th e cours e o f

time i s compensate db

y raisin g th e temperature'ac

- cordingly . Carbo n deposit s ar e remove dfro m tim e t o tim e by burning . Th e presenc e of water i n th e feedstoc k

mixture suppresse s th e decom

- positio n o f

methanol , extend s th e regeneratio n cycle , an dprolong s th e lifetim e o f th e catalys t [103] , [104] , whic h ma

y the n endur e for

severa l thousan dhours . % Th e produc t

mixtur e leavin g the reacto r give s u p som e o f it s heat t o th e feedstoa

k mixtur e i n aP.5 2 3 6 Cresol s an d Xylenol s Vol
. A 8 hea t exchanger , an di s then condensed . Th e un coiulensabl e reactio n product s formed fro mIh e decompositio n of

methano l (H 2 , CH 4 , C0 2 , an d CO ) ar e use

da s fue l ga s i n stea mproduction . Aqueou s methano l i s first distille dfro

mth e liqui dreactio n produc t

an dthe n recycled . Water remainin g i

n the produc t

i s then remove deither b y azeotropi c distillatio n wit h toluen e [102

] o r a s a n azeotropi c mixture wit h unreacte dpheno l [101] . I n th e latte r

case , i t i s necessar

y t o stri p the pheno l fro

mth e wastewater . Th e dehydrate d mixture is-the n fractionate dint o pheno l ether , phenol , o-cresol ( > 99.5%) , an d2,6-xyleno l i n a n additiona l serie s o f

highly efficien

t distillatio n column s operate dcontinuousl y under vacuum . Th e pheno l ether-pheno l fractio n i s recycled . Th e distillatio n residue , whic h contains , amon g othe r compounds , 2,3- , 2.4- , an d2,5-xyleno l an d2,4,6

- and2,3,6-trimethylphenol . i s usually burne da s afue

l oil . I f th e catalys t

ha s high orth o selectivity , pur

e (99.5% ) 2,6-xyleno l ca

n be ob

taine ddirectly . I

f tha t i s no t th e cas e o r

i f th e reactio n condition s ar e to o sever e (high tempera ture , lon g residenc e time) , th e 2,6-xyleno l frac

tio n wil l contai n m- an dp-cresol , whic h mus t be remove db

y specia l method s (cf

. 49) . Th e rati o of o-creso l to 2,6-xyleno l ca

n b e controlle db

y alter

in g th e methanol-pheno l ratio , an di f th e o creso l i s recycled , 2,6-xyleno l comprise s th e sol e product . Ove

r a n extende dproductio n time , the yield(selectivity ) of

o-creso l an d2,6-xylenol , cal

culate don the basi s of reacte dphenol , i s 90-95% . Wit h regar dt o th e us e o

f afluidized-be d reacto r fo r thi s reaction , see [105] , [106] . Vapor

liqui dequilibriu mdat afo r the alkylatio n prod

uc t ar c give n i n [107] , an ddetail s o f

th e distilla

tio n in[108]-[110] . Magnesium oxide catalysts , i n particular , ar e used . They require relativel y hig h operatin g tem perature s (420-460"C) , bu t ar e s o ortho-selec

tiv e that m- an dp-creso l ar e hardl y formed , eve n a t 54 0 'C [111] . Th e activit

y (pheno l conversion) , a s wel l a s th e rati o of

2,6-xyleno l t o o-creso l an d th e orth o selectivit

y depen do

n th e condition s under whic h th e magnesiumoxide i s produce d [112]—[114] . Thes e propertie s ca n be further

im

prove db y combinin g magnesiu moxide wil h oth

e r oxides , suc

h a s thos e of

manganes e [113] , [115] , coppe r

[113]-[115] , titanium , uranium , zirconium , chromiu m[116] , an dsilico n [117] . A t 44 0 ° C an da t

aliqui dhourl y spac e velocit y (LHSV ) o f

2. 0 h " ' th e continuou s reactio n o f a mixtur e o f

phenol , methanol , an dwate r i n a 1:4:2. 4 molar

rati o over

aMg O catalys t

thu s give s apheno l conversio n of ca . 82% , an da mola r ratio o f 2,6-xylenol , o-cresol , p-cresol , 2,4-xylenol , an d2,4,6-trimethylpheno l of 69.5 : 23.0:0.05:0.8:6.6 . I

f th e catalys t

als o contain s ca . 1 % of

copper , the conversio n rat e i s 89% , an dth e correspondin g mola r rati o of th e prod

uct s i s 73.3:18.9:0.06:0.07:7.0 . Th e wast e ga s volume i s i

n bot h case s 0. 5 mol per

mol e o f reacte dpheno l [114] . Th e mechanis mof orth o methylatio n i s discusse di n [118] . Wit h manganese oxide catalysts , th e methyl

atio n ca n be carrie dou t

a t ca . 420 ° C [119] ; o n chromium oxide catalysts , a t ca . 39 0 ° C [120

] — [122] ; an do n catalyst s base do n vanadium oxide [123] , [124] o r

iron oxide [125]-[130] , a t ca . 35 0 C C , provide dtha t

thes e oxide s ar e combine d wit h smaller amount s o f

othe r oxide s (e.g. , o f Co , Ni , Zn , Al , Ga , Si , Ge , Sn , Pb , Bi , Mg , an d Na ) o r wit h on e anothe r

[131]—[134] . Thes e mixedoxide catalyst s sho w excellen t orth o selec

tivit y an dgive aver

y hig h 2,6-xylenol/o-creso l rati o an dvirtuall y n o p-cresol . At phenol/ methano l mola

r ratio s of ca . 1:5- 6 an dliqui d hourl y spac e velocities'(*LH§\Q o f ca . 1 h" ' they permi t almos t complete conversio n of

phenol , wit h 2,6-xyleno l yield s of

ca . 95 % (calculate do n th e basi s o f

phenol) . Combinatio n wit h othe r meta l oxide s als o extend s th e catalys t lifetim e (especially i

f alkali-metal compound s ar e added ) an ddiminishe s th e extensiv e decompositio n o f methano l typicall y see

n wit h manganese , chro

mium , vanadium , an diron,.oxid e catalysts . In spit e of thi s measure an dth e additio n of water vapo r (generall y 1- 2 mo l pe r

mol e of phenol) . 1- 2 mol of

methano l ar e usually los t b y decom

positio n fo

r ever y mol e o f 2,6-xyleno l manufac

tured . Th e propose dmethod s fo r reducin g th e los s includ e th e additio n o f sulfu r dioxide , hy

droge n sulfide , nitri c oxide , carbo n monoxide , o r carbo n dioxid e to th e feedstoc k mixture [135] , recycling aportio n of

th e crackin g ga s [136] , an d introducin g th e methano l [137 ] o r pheno l at dif

feren t part s o f th e .reacto r

[138] . Relatively littl e methano l i s decompose don Fe 2 0 3 catalyst s dope dwit h silico n oxide an dmagnesiumoxid e [128] . Fo r th e mechanis mof

th e reactio n on mixe doxide contacts , se

e [139] , [140] . y-Aluminum oxide catalyze s th e methylatio n of pheno l at atemperatur e a s lo w a s 300-32 0 °C . Under-rthes e conditions , at amethanol:pheno l molarTati o o f

1:2 , an da t

aliqui dhourl y spac e velocit y (LHSV ) of

1 h" 1 , o-cresol , 2,6-xylenol , an dm-^p-cresol mixture ar e forme di n amola rP.5 3

Vol
. A 8 rati o of ca . 82:17:1 , wil

h atotal selectivit

y of 97 % an dapheno l conversio n of 33 % [141] . In

- greasin g th e methanol:pheno l ratio an drecy - clin g the o-crcso l enable s the ..-crcsol:2,6

- xvleno l rati o t o be shiftedtowar d2,6-xyleno l [142] . O n y-AI 2 0 ;) , unlik

e oilier methylatio n cata - lysts , methano l i s scarcely decompose dunder th e condition s describe dabove . I n addition , thi s cat - alys t mus t be regenerate donly onc e i n ca . 100 0 h . an dha s aworkin g lifetim e of severa l year s [143] . It s disadvantag e i s tha t t o prevent th e formatio n o

f significan

t quantitie s of

othe r di- , tri- , an dtetramethylphenols , th e pheno l con - versio n rat e mus t

no t substantiall y excee

d60% , whic h mean s tha t

relativel y larg e amount s of th e produc t mus t b e worke du p an drecycled . I n addition , extensiv e operations , e.g. , extractiv e distillatio n wit

h diethylen e glycol [142] , are nec - essar y to fre e th e 2.6-xyleno l fro

mth e p-creso l tha t i s unavoidabl y formedon thi s catalyst . Belo w 300'C . increasin g amount s of anisol e are forme do n y-Al 2 0 3 ; however , becaus e ani

- sol e i s isomerize dt o creso l a t elevate dtempera - ture s [144] , [145] . only asmal l amoun t ( < 2.5% ) i s presen t i n th e reactio n mixture unde r th e pre - viously mentione dconditions . A s th e tempera - ture an dresidenc e tim

e are increased , th e rate of pheno l conversio n o n Al 2 0 3 rises , bu t th e orth o selectivit y falls . Thi s i s als o basically tru e of oth

- e r catalysts . Instea do f

o-creso l an d2,6-xylenol , increasingly larg e amount s o f in- an dp-cresol , othe r xylenols , multimethylphenols , an dmethyl

- benzenes , especially hexamethylbenzene , ar e forme d[146] , [147] . Demethylatio n occur s abov e 500' C [148] . Increasin g the temperatur e als o re - sult s i n th e formatio n of

large r amount s of gaseou s crackin g products , an daccelerate s th e carbonizatio n of

th e catalyst , thu s necessitatin g mor e frequen t regeneration . Th e reactio n kinetic s an dth e choic e an dcal

- culatio n of

a n optimu mmultitubular

reacto r fo r pheno l methylatio n on -/-Al 2 0 3 ar e discusse di n [149 ] —[151] . Industria l plant s ar e describe di n [99 ] an d[142] . Aluminum oxides with sirong acid sites [152] , silica-alumina [118] , [153] , zeolites [153]-[156] , aluminum phosphates [147] , [158] , an dphosphoric ticid-kicselgitlir

[158 ] hav e enhance disomeriza

- tion an dtransmethylatio n properties . Therefore , the y lea dt o product s wit

h arelatively hig

h m/ p content , especially i

f th e temperatur e i s simul

- taneously raise dto ca . 45 0 C C . I n addition , at

a temperature o

f 250-30 0 °C , shape-selectiv e Cresol s an d Xylenol s 3 7 zeolite s [154] [156] , e.g. . o f the HK Y typ e [154] , an dals o phosphori c acid-kieselguh r [158] , sho w remarkabl y high selectivit y fo r p-cresol , givin g am-/p-creso l mixtur e wit h p-creso l con - tent s of ca . 85 % [154] o r

77 % [158] , respectively . Titanium dioxide als o show s par aselectivit y [158] . A s alternative s t o methanol , methylbenzene s [160] , [161] , dimethy l ethe r

[162] , methylamin e [163] , methan e [164] , carbo n monoxide-hydroge n mixture s [165] , an d formaldehyde-hydroge n mixture s [166 ] hav e been pro - pose da s methylalin g agents . Methylatio n i

n th e vapo r

phas e i s utilize db

y Genera l Electri c i

n th e Unite dState s (capacit y ca . 1000 0 t/ao-creso l and70 000 t/ a2.6-xy

- lenol ) an di

n th e Netherland s (ca . 4000 t/ aocreso l an d1600 0 t/ a2,6-xylenol) ; by Crod aSyn

theti c Chemical s i

n th e Unite dKingdo m(ca . 8000 t/ ao-creso l an d2,6-xylenol) ; an di n Japa n b y Nippo n Creno l (joint

venture of

Asahi Chem

- ica l an dNippo n Stee

l Chemical ; 500

0 t/ ao - creso l an d1000 0 t/ a2,6-xylenol ) an dGem

- Polyme r (join t ventur e of

General Electri c an d Mitsui ; 230

0 t/ ao-creso l an d1800 0 t/ a2,6

- xylenol) . Th e facilitie s o

f Conoc o an dKopper s i n th e Unite dState s wer e close ddow n (tem

- porarily ) i

n 198 3 fo

r marke t reasons . Cindu , Riitag , an dMidlan dYorkshire Ta r Distillers ' (CRM ) plan t

i n th e Unite dKingdo mha s bee n take n ove r b y Croda . Vapor-phas e methylatio n plant s ar c sai dt o b e i

n operatio n in th e USS R [143 ] an di

n Czechoslovaki a[150] . Methylatio n i

n the Liqui

dPhase . Result s sim

- ila r t o thos e achieve di

n the vapo r

phas e ar e obtaine di

f the oxide catalyst s (particularl y V-Al 2 0 3 ) are suspende di n aphenol-methano l mixture an dheate di

n a n autoclav e t o 300

- 400° C [167]-[169] . Th e mixture of pheno l an d methano l [170

] o r of o-creso l an dmethano l [171 ] ca n als o be passe da s aliqui dove r a-/-A1 2 0 3 catalys t formin g afixedbe

di n atub e reactor . A t 350" C an daphenol:methano l mola r rati o o f 0.7:1 , th e pressure i s ca . 3 5 ba r [170] . Accordin g t o aproces s operate db y Chemi

- sche s Wer k Lowi , Federal Republi c o f Germany , pheno l an da

n equimola

r amoun t of methano l ar e reacte di

n a n autoclav e at

350-40 0 ° C i

n th e presenc e of

2- 3 wt % aluminum methylate, wit h th e wate r of th e reaction , together

wit h som e of th e methanol , bein g distille dthroug h asmall col

- umn . Afte

r th e catalys t

residu e haste n re „ move db y filtration, th e produc t

i s worke du p by distillation . Methanol , anisole , an dpheno l ar eP.5 4 3 8 Cresol s an d Xylenol s Vol
. A 8 recycled . Th e yiel

dof cresol s an

dxylenol s i s ca . 80 % [172] , calculate do n the basi s of reacte d pheno l (ca . 60%) . Th e mai n produc t i s o-cresol ; m- an dp-cresol , 2,6- , 2,4- , an d2.3-xylenol , an d trimethylphenol s ar e als o formed . Th e ratio o f th e product s ca

n be adjuste db

y alterin g th e phe

nol .methano l ratio , the temperature , an dth e residenc e time . Th e presenc e of base s (e.g. , py ridine ) increase s th e conversio n [173] , wherea s tha t o f acid s raise s th e proportio n ofp-creso l an d 2,4-xyleno l i

n th e produc t

[174] . Aluminumphe

nolat e can als o b e useda s acatalys t [175] . I f necessary , th e proces s ca

n b e operate di

n amulti

purpos e plant , th e capacity o f whic h ma y be ca . 2000-300 0 t/a . Unio n Rheinisch e Kraftstof f AG operate s a proces s in th e Federal Republi c of German y tha t use s liquid-phase catalysts [176] , [177] , prefer

abl y aqueou s zin c halide-hydroge n halid e solu

tion s [178] , at

200-24 0 ° C an dpressure s of ca . 2 5 ba r (2. 5 MPa) . Afte

r th e reaction , the organi c component s ar e separate dfro mth e aqueou s cat alys t phas e b y extractio n wit

h benzene o r

cyclo

hexane , washe dwit

h wate r severa l limes , an d worke du p b y distillation . Th e catalys t solutio n i s unite dwit

h th e washin g water , concentrated , an drecycle d[179] . Th e mai n product s ar e ocresol , p-cresol , 2,4-xylenol , an d2,6-xylenol . At aphenol : methano l mola

r rati o of 1:0.6 , yield s o f u p to 98% o ar c obtainable , calculate do n ihe basi s o f reacte dphenol . Compare dwit h othe r processes , thi s ha s th e advantage s no t onl y tha t p-creso l an d2,4-xyleno l ar e obtaine di n consid

erabl y large r

quantities , bu t

als o that , provide d the reactio n condition s ar e carefull y harmo

nized , th e p-creso l i s almos t fre e of m-cresol . Th e extent o f par asubstitutio n increase s wit h th e methano l conten t

o f th e feedstock

mixture , bu t the yieldfalls . Th e proces s require s material s tha t ar e highl y resistan t

to corrosion , e.g. , areac to r linedwit h tantalum . Th e plan t

ha s acapacity o f ca . 1600 0 t/a . Th e produc t rati o i s con trollabl e withi n certai n limits . A s a n example , th e o-cresol , p-cresol , 2,4-xylenol , an d2,6-xyleno l rati o ca n b e 7:5:2:1 . Transmethylatio

n an d Isomerization. Afte

r pheno l ha s bee

n adde dt o th e methylpheno l resi

due s eithe r

fro mth e methylatio n of

pheno l o r of differen t origin , o r

t o 2,6-xyleno l fo

r whic h there i s n o othe r

use , reactio n ca

n occu r i n ih c presenc e o f alkylatio n catalyst s t o giv e aproduc t con sistin g mainl y o f

o-cresol , togethe r

wit h m-jpcresol . Th e reactio n ma

y procee deither

i n th e vapo r

phas e o r in th e liqui dphase ; th e tempera ture i s 400-500°C . Catalyst s ar e aluminu m oxid e [180] , chromiu moxide-aluminu moxide [181] , silica-alumin a[182] , metal oxide-iro n oxid e [183] , ormagnesiu moxide-tungste n oxide [184] . In th e cas e of

2,6-xylenol , thi s transmethy

lation , accompanie db

y isomerization , ca

n als o be accomplishe dwithou t

acatalys t in th e vapo r phas e a t 550-60 0 ° C or , batchwise , i n th e liqui d phas e at 420-470" C [185] . I n thi s way , th e o creso l yieldfro

mth e methylatio n o f

pheno l ca

n b e raised . Owin g t o th e temporary lac k o f deman dfo

r o-cresol , opportunitie s fo r isomerizin g i t

t o man dp-creso l hav e bee

n investigated . Th e result s formerl y obtaine dwit

h aluminu mchlorid e [186] , [187] , aluminu mfluoride , boro n trifluoride , alu

minu msilicates , o r

aluminu moxide wer

e un satisfactor y [187] , [188 ] becaus e resinificatio n an ddisproportionatio n to phenol , dimethyl

phenols , etc . occurre di

n additio n t o isomeriza

tion . Isomerizatio n withou t

substantia l dispropor

tionatio n i s possible , however , on silica-alumin a zeolite s of th e ZSM . group s at

atemperatur e of ca . 400° C an do-creso l conversioh's'o f 40-50% , /..-/p-creso l selectivitie s o f

90 % an dan m: p ratio o f 7: 3 ar e possibl e [189] . 1.4.5 . Othe r Route s Th e risin g deman dfo

r creso l ha s stimulate d th e developmen t

o f numerou s syntheses , espe ciall y thos e tha t

lea dselectively t o certai n creso l isomers . I t

appears , however , tha t

thes e process e s ar e no t ye t bein g usedindustrially . Gul f Oxychlorination . A creso l synthesi s ana logou s t o th e Raschi g pheno l synthesi s canno t b e carrie dou t

satisfactoril y unde r

industria l condi

tions : at th e temperatur e neede dfo r oxychlorina

tio n in th e vapo r

phas e (5) , toluen e i s oxidize dt o aconsiderabl y greate r

exten t tha n benzene , an d onl y lo w rate s o f

toluen e conversio n are , there

fore , possible . CH 3 -C 6 H 5 + HC ! + 0. 5 O j — - CHj-C,H 4 -C I + H, 0 (5 ) CHj-C.H.-C l + H, 0 — . CHj-C„H 4 -0 H + HCl (6 ) I n aproces s develope db y ih e Gul f Researc h Develop

ment Co. , thes e disadvantage s ar e avoide db y oxychlori

natin g th e tolirffi e wit

h aqueou s hydrochlori c aci dan d oxyge n a l atcrffljeratur

e o f ca . 100° C i

n th e presenc e o f catalyti c amount s p f

nitri c aci dan dapalladiu mo r coppe r sal t [190] , [191] . At

toluen e conversio n rate s o f 80% ,P.5 5

Vol
. A 8 Cresol s an d Xylenol s 3 9 primaril y o- an d/.-chlorotoluen e ar e obtaine d i n a2: 1 molar rati o an dwilh aselectivit y o f > 95% . Th e subsequen t

hydrolysi s o f

th e chlorotoluen e mix

- lur e i s oarric d ou t

i n ih e vapo r

phas e a t 400-450°C , a s i

n ih e Raschi g process , bu t

ove r improve dcatalysts , suc h a s lanthanu mphosphat e tha t ma y b e activate d wil

h coppe r [l.2| . A t achlorotoluen e conversio n o f 20% , ih c creso l selectivit y i s ca . 95% . Th e isome r rali o differ s fro mlha l give n b y th e processe s alread y bein g usedindustrially . A larg e amoun t

o f o-creso l i s obtaine di

n additio n lo/.-creso l containin g soni c »r-crcsol . I f the hydrochlori c aci dse

t fre e i n th e hydro

- lysi s step (6) i s returne dt o the oxychlorinatio n reactor , th e proces s become s equivalen t t o th e oxidatio n of

toluen e wit

h oxygen . Thi s fact , to - gether wit h th e high conversio n rate s an dselecti

- vities , make s th e proces s interesting . Commer

- cia l exploitatio n o f

th e proces s necessitate s th e extensiv e recyclin g an dpiace s sever e demand s on the resistanc e of

th e plan t to corrosion . Th e Gul f oxychlorinatio n proces s i s equally applicabl e to xylenes , an dis , therefore , als o suit

- abl e fo r th e manufactur e of

xylenols . Oxidativ e Decarboxylatio n o f Methyibenzoi c Acids . A s i

n the Do w proces s fo

r th e manufac

- tur e of pheno l fro

mbenzoi c acid , methyibenzoi c acid s are decarboxylate dt o creso l whe n a n air

- stea mmixture i s passe dthroug h thei r mel t a t 200-24 0 ° C i

n th e presenc e o

f coppe r an dmag - nesiu msalt s [193] . CH 3 

# 6 " COO H + l/ 2 0 j O H + C0 2 B y compariso n wilh th e manufactur e o f phenol , ih e creso l proces s i s mor e comple x an d10-15 % les s selectiv e (48) . Thi s i s du e partl y t o th e fact tha i cresol s hav e higher boilin g points ; i

n consequence , optima l conlro l o f Ih e reac - tio n i s difficult , an dagreate r amoun t o f lar i s forme d[193] . I n addition , th e simultaneou s successiv e oxidatio n o f th e methy l grou p lead s t o numerou s byproduct s [194] . Oxida

- tio n i n th e presenc e o f

benzoi c aci dha s been propose d[195 ] a s amea n o f preventin g th e sublimatio n o f methyibenzoi c acid . Bette r result s ar e achieve dwhe n amethyibenzoi c acid

- stea mmixtur e i s oxidize di

n th e vapo r

phas e wit

h oxygen - nitroge n mixture s ove r

mixe dcatalyst s a l atemperatur e of ca . 300° C [196] , [197] . Thus , th e reactio n o f amixtur e of /•-methyibenzoi c acid , water , oxygen , an dnitroge n (molar ratio.o f 1:18:1:9 ) a l 300" C ove r aMo-V-Cu-Zn-N a oxid e catalys t supporte do n y-AI,O

j i s reporte dt o give a m-crcso l selectivit

y o f 90 % a l amethyibenzoi c aci d conver - sio n rat e of 80% ; a s byproducts . 2 % toluene , 5 % bis

- (methylphcnyl)-bis(mclhylphenyl ) ethe r mixture , an d3 % o f additiona l carbo n dioxid e ar e forme d[197] . The proces s coul db e of

interes t i n th e manu - factur e o f pur e ///-cresol . sinc e only ///-creso l i s forme dfro mbot h th e orth o an dth e par aform s of methyibenzoi c aci d[48] , [193] . m-Methyl

- benzoi c aci dgive s (in th e liqui dphase ) o - an d p-creso l i n a1: 2 ratio [198] , [199] . Regardin g th e mechanis man dkinetics , se e [193] , [194] , an d [200] , respectively . Th e require dmethyibenzoi c acid s ca n be obtaine db

y oxidatio n o f

th e correspondin g xylenes , whic

h are , however , more expensiv e than toluene . Baeyer-Villige r Oxidatio n o f p- o r oMethylbenzaldehyde. Thi s rout e lead s t o o-creso l or , more interestingl y fro

mth e practical aspect , specificall y t o p-cresol . Hydroge n peroxid e re - act s wit h exces s formi c aci dt o give performi c aci d(7) , whic

h oxidize s p-methylbenzaldehyd e top-toly l formate (8) ; hydrolysi s (9 ) the n lead s to p-creso l an dformi c acid .

_ _HGOOO H + H_ 0 (7 ) O-CH O (8 )

(B )

Severa l variant s ol " ih e proces s hav e been develope d [201]-[203] . Th e mos t

favorabl e proces s wa s probabl y in

- vente db y Mitsubish i [2()4| . Hydroge n peroxid e (1. 2 mol ; 90% ) i s adde dt o amixtur e consistin g o f 1 mo l o f

pmelhylbenzaldehyde . 1 4 mo l o f formi c acid , an dca . 10 % (4. 5 mol ) o f

water . Th e temperatur e o f ih c mixtur e i s main

- taine da l 60 -90'C : ih e hea l o f th e reactio n i s remove db y reflux condensatio n unde r vacuum . Becaus e o f

th e pres - enc e o f water , format e i s hydrolyzed ; aflc r areactio n lim e o f 1 li . th e /'-mcthyllx-iizaldcliyd c conversio n rale i s 100 % an dth e p-creso l yiel di s 85% . If , instea do f

90 % hydroge n peroxide , performi c aci di s used , o r if th e proces s i s carrie d ou t i n th e presenc e o f

asoli daci d(zeolite o r

ion-exchang e resin) , th e yiel drise s t o 90-92% . Th e produc t i s worke dup b y distillin g th e formi c acid . Apar t fro mth e additiona l amoun t forme di n th e process , th e formi c acid , whic h ha s aconcentratio n o f

ca . 9 0 % , i s recycled . Th e p-creso l i s the n isolate dfromth e residue , whic h stil l contain s 10-20 % o f high-boilin g constituent s [204] . Th e startin g material , p-methylbenzalde

- hyde , ca n be produce dfro

mtoluen e an dcarbo n monoxid e b

y th e so-calle dMG C PTAL proces s develope db

y Mitsubish i [205] . It

i s a n inter

- mediate i n th e manufactur e o f

terephthali c acid . Nucleu s Hydroxylation . Th e direcwfiydroxyl

- atio n of toluen e (o r

xylene) , e.g. , with , oxygen [206] , hydroge n peroxid e [207] , [208] , inorgani cP.5 6 

### 4 0 Cresol s an d Xylenol s Vol
. A 8 perox o compound s [209] , o r organi c peroxide s [210] , [211] , i

n th e presenc e o

f variou s catalys t system s (Friedel-Craft s catalysts , transition

meta l compounds , o r

irradiation) , ha s bee

n ex tensivel y investigated . Accordin g l o Rhone-Poulenc , th e mos t successfu l re sult s s o fa r

hav e bee n obtaine dwit h 85 % hydroge n perox id e i n th e presenc e o f

alarg e amoun t

o f Irifluoroinethanc

sulfoni c aci dan dasmal l amoun t o f phosphori c aci d(fo r complexin g meta l ions ) [212] . CH , 

# 6 " | + HgO j CH 3 

# _^°^^jf ( +

„0 H CH

3

• 2 0 K O H 1 A t —2 0 t o —15" C an damola r rati o o f

H 2 0 , , toluene . CFjSOjH , an dH^PO^ofca . 1:10:17:0.04 . (--an d /•-creso l ar e obtaine di n a2: 1 rati o i n 80 % yiel d(calculate d o n ih c basi s o f

hydroge n peroxide ) a l atoluen e conversio n rat e o f 10.6% . On e o f

th e problem s i s th e recyclin g o f th e ver y expensiv e irilluoromclhancsulfoni c acid . Wor k carrie dou t

b y UO P indicate s lha l relativel y goo dresult s ar e obtainabl e wit h hydroge n fluoride , whic h i s les s expensiv e an deasie r t o handl e industriall y tha n tri

fiuoromclhanesulfonic acid , i n th e presenc e o f carbo n di

oxide . Wit h 30 % hydroge n peroxid e a t 0" C an da l amola r rati o o f H 2 O j , toluene , H F , an dCO , o f 1:10:70:10 , o - an d /--creso l ar e obtaine di n a2:' l rati o i n 67 % yield , base do n hydroge n peroxide , i n additio n l o asmal l amoun t o f .**

- cresol . m-Xylen e give s mainl y 2,4-xylenol , p-xylen e mainl y 2.5-xylenol , an do-xylen e mainl y 2,3

- an d3,4-xyleno l [213] . Th e effec t o f th e carbo n dioxid e i s no l full y understood , bu l thi s compoun dact s t o som e exten t a s a n interna l coolant . O n titanium-modifie dzeolites , o-. «/- . an dp-crcsol s i n a14:11:7 5 rati o ar e forme di n ayiel do f a t leas t 40% , base do n H,0 2 , whe n amixtur e o f H,0 2 , water , toluene , methy l isobuty l ketone , an dtitaniu mzeolit e (preireate d wit h HjPO J i s heate dunde r reflu x i n amas s rati o o f 1:7:17:10:2.6(214] . IC I ha s develope dacycli c proces s equivalen t t o th e oxidatio n o f

toluen e wit h peraceti c acid , whic h give s yield s o f u p t o 95 % o f

a n o-/p-creso l mixture , fre e o f th e met a isomer , wit h acreso l conten t o f 92% . Th e "catalyst " i n th e reactio n i s iodotoluene . Thi s i s oxidize db y peraceti c aci dl o iodosyltolucnc , whic h withou t isolatio n react s wit h lolucn e an dsulfuri c aci dt o for mditolyliodoniu mhydroge n sul

fate . Hydrolysi s i s effecte db y dilutin g th e reactio n mixture . Creso l i s produced ; iodotoluen e i s simultaneousl y regen erate dan drecycle d[215] . Al l processe s involvin g nucleu s hydroxyla

tio n ar e unsatisfactor

y fo r severa l reasons ; fo

r example , th e cresol s mus t b e isolate dfro

mver y dilute solutions , an dconsiderabl e amount s o f auxiliarie s an dunreacte dstartin g material s need t o b e recycledwit

h a s littl e wast

e a s possible . Oxidativ e Methylatio n o f Toluene . I n th e USSR , a pilo t plan t ha s bee n operatin g i n whic h toluen e i s oxidize d adia baticall y i n a lub e reacto ra t 70 0 75 0 " C an d wit h conlac t tim e o f 0.2-0. 5 s wit h oxyge n i n th e presenc e o f methan e an d stea m (mola rrati o 1:1-2:10-20:2-6 ) [2161
. [217]
. CeHj-CH-jCH.,- * CeHj-CH-CH j 

## 3 * CjHj-CH , + 0 2 + CH 4 —^CgHgO H + C^-Cg^-O H CeH e A t atoluen e conversio n o f

ca . 45% , 0.5 2 t

o f styrene . 0.2 5 t o f benzene , ca . 0.1 1 t

o f phenol , an dca . 0.0 6 t

o f creso l ar e obtaine dpe r

to n o f toluen e [218] , [219] . Thus , i f th e proces s wer e t o b e use do n th e scal e customar y fo r petrochemica l operations , i t shoul db e possibl e t o produc e considerabl e amount s o f

creso l b y th e "direc t

oxidation " o f toluene . Hoc k Reactio n o f

Toluen e Derivatives . A s i n th e cymene-creso l process , othe r toluen e hydrocarbon s ca n b e peroxidize dan dcleave dt o give creso l an dth e correspond

in g carbony l compound . Particula r interes t ha s bee n show n i n toluen e derivative s lha l give p-creso l an dar e mor e readi

l y accessibl e tha n p-cymene , e.g. , ethylidenebis(p-methyl

benzene ) (coproduct : p-methylacetophcnone ) [220] , [221] , 4-methyl-cyclohexylbenzen e (coproduct : cyclohexanone ) [222] , andp-xylcne(coproduct : formaldehyde ) [223] , [224] . Oxidatio n o f

xylen e i n th e presenc e o f

aceli c aci dgive s th e correspondin g cresy l acetate , whic h ca n b e hydrolyze dt o for mcreso l [225] . Hydrogenatio n o

f N,N'-Dialkylaminomethylphenols . Th e reactio n o f

pheno l wit

h paraformaldehyd e and , e.g. . piperidin e i

n methano l a t

a2:1:1:10 0 mola r

rati o a t ca . 1 0 ° C give s amixtur e of.piperidinomethylphenols . whic h withou t isolatio n i s directl y hydrogenate da t 120-130° C an d1 MP aove r

apalladium-carbo n catalyst : O H O

H <^f> Uotlumo

l K^> ^ \/ Pd/ C o an dp 1_0-130» C

1 MP . O H 

# 'Q- C H 3 + H 

# O o/p s 1 : 2 o-Creso l an dp-creso l i

n a1: 2 molar

rati o ar e obtaine d i n ayiel dof

ca . 90% , base do n reacte dphenol , o r o f abou t 75% , base do n th e formaldehyd e input . I n addition , som e 2,4-xyleno l i s forme d(2-5% ) withou t m-creso l [226] . Th e yiel di s lower

(65-70% ) if

dimethylamin e i s substitute dfo r piperidine . Diels-Alde r

Rin g Closure o

f Isopren e an

dVinyl Ace

tate . Th e Diels-Alde r

rout e lead s selectively t o p-crcso l i n thre e reactio n steps : (1 ) Isopren e ( 1 mol ) react s wit h viny l acetat e (2 0 mol ) i

n th e presenc e o f

1 % hydroquinon e i

n a n autoclav e a l 180°C ; (2 ) th e reactio n product , 1-mcthyl

cyclohcxene-4-y l acetate , i s saponified ; an d(3 ) finally, th e l-methylcyclohexen-4-o l i s dehydrogenate dcatalyticall y t o p-creso l [227] :

.OCOCH j 

# •jy OCOCH 3 KOH^Q H 

# JT Reflu x 1 h sio- c HC \ ^ O

HP.5 7

Vol
. A 8 Cresol s an d Xylenol s 4 1 Hig h yield s are claime d l o be possibl e whe n ih e starlin g material s ar

c recycled .

. Carbonylation . 2-Methally l chloride , acetylene , an d carbo n monoxid e i

n aceton e a s solven t

giv e ***-creso

l i n 74 % yielda

t roo mtemperature . CH , CH 2 =C-CH 2 -C 1 + HC=C H + C O O H Nl(CO), . Nil . M«

0 

### "' ' L K CH 3 Fe , thioure a O H 

# 6 * HC

l Th e catalys t

consist s o f

tetracarbonylnickel , sodiu m iodide , iro n powder , an dthiourea ; magnesiu moxid e neu - tralize s th e hydrochlori c aci dforme d[228] . FromToluidincs . Unde r

sever e conditions , toluidinesi n th e presenc e o f

acidi c catalysi s (H 3 P0 4 , HCl , ZnCl 2 , BF J ca n be hydrolyze di o for

mth e correspondin g cresol s [229] , [230] . Highe r

yield s can b e achieve db y boilin g th e diazo

- niumsalt s obtainabl e fro mtoluidine s [231] , [232] . Continu

- ou s operatio n o f

th e proces s i s describe d i n [233] . Hydrodealkylatio n o

f Xylenols . Xylenol s can b e de

- methylate d l o pheno l an dcresol s wit h hydroge n unde r pressure , eithe r

thermall y a l 60 0 700" C [19 ] o r o n metal oxid e catalyst s a

t 400-500' C [234] . Simultaneou s de

- oxygenatio n enable s BT X aromatic s (BTX = benzene

- toluene-xylene ) t o b e produce da t th e sam e time . I

n thi s way , additiona l cresol s can b e produced , i f necessary , fro m ihe xyleno l fraction s lha l ar e forme do n alarg e scal e i n th e gasificatio n an dhydrogenatio n o f coa l an d othe r

pro - cesses . 

### 1.5 . Separatio n o f

m- an d/.-Creso l [24

] Onl y o-creso l ca

n be separate da s apure produc t b y distillatio n fro

mmixture s o f

th e thre e creso l isomers . m-Creso l an dp-creso l ar e ob

- taine da s asingl e fractio n becaus e th e differenc e betwee n thei r boilin g point s i s to o smal l fo r sepa - ratio n b y distillation , eve

n whe n carrie dou t

un - de r vacuum . 1.5.1 . Physicochemica l Processe s Crystallization . Accordin g t o th e meltin g point diagra mfo

r m-/p-creso l mixture s (Fig . 1) , i t i s possibl e t o obtain , at

normal pressure , pur e p-creso l fro

mmixture s containin g mor e tha n 58 % p-cresol , an dpur e m-creso l fro mmixture s containin g more tha n 8 9 % m-crcsol . Mcta/par a mixture s containin g 42-89 % of 7?i-creso l canno t b e separate db

y crystallizatio n a l normal pres - sur e becaus e m

- an dp-creso l exis t

a s amolecula

r compoun di

n a2: 1 mola

r rati o withi n thi s con - centratio n range . (p-Cresol ) 2 0 -am

6 0 Creso l fraction , % • 80 10 0 (m-Cresol ) Figur e I . Liquid-soli dphas e diagra mo f /*•

- an dp-creso l mixture s unde r pressur e [235 ] Th e rang e withi n which p-creso l can be , iso

- late db y crystallizatio n ca

n b e extende dby ap - plyin g pressure (Fig . 1) ; simultaneousl y th e crystallizatio n temperatur e an dals o th e p-creso l yields , relativ e t o crystallizatio n a t norma l pres. ; sure , ar e raise d[235] . Crystallizatio n i s of

practical importanc e a s a techniqu e fo

r th e separatio n o f

pur e p-creso l fro mm-/p-creso l mixture s of hig h p-creso l con - ten t obtaine dfro

msynthese s o r

othe r processes . Up l o now . thi s metho dha s generall y bee n carrie dou t

a t normal pressure . I

n Japan , ahigh

- pressure crystallizatio n techniqu e know n a s th e Finecry process, i

n which aliqui dm-/p-creso l mixture i s introduce dint o ahigh-pressur e vesse l of th e pisto n cylinder

typ e an dcrystallize d adiabaticall y at

20 0 MPa , ha s been recentl y de

- velope dfo

r industria l us e by Kob e Steel . Afte r th e mothe r

liquo r ha s bee n draw n of

f an dth e plan t decompressed , th e p-creso l emerge s a s a pur e crystallin e product . Th e computer-con - trolledcrystallization-decompressio n cycl e last s 2- 5 mi n [236] . I t ha s bee n reporte dtha t

aplan t fo r th e manufactur e of

50 0 t/ ao f p-creso l i s t o b e constructe dfor

Sumitom o Chemical i n Japa n [237] . Adsorption . Alkali metal-modifie do r al

- kalin e earth metal-modifie dzeolite s o f typ e X , A [238] , L , o r

ZMS5 [239] , an dals o titaniu mdiox

- id e [240] , adsorb p-crcso l more strongj y tha n mcresol . Thus , on e ca

n separat e m-/ps(cresol mix

ture s in a n adsorptio n column an ddissolv e the m agai n wit h asuitabl e desorbin g liqui dsuc h a s a nP.5 8 4 2 Cresol s an d Xylenol s Vol
. A 8 aliphati c alcoho l [238 ] o r

aketon e [241] . A con tinuou s versio n of

thi s proces s ha s bee

n devel

ope db y UO P [93] . I t

i s know n a s th e Cresex proces s an di s use

dindustriall y i

n the Unite d State s b y Merichem . Th e separatin g efficienc y o f the proces s no t

only depend s o

n ihc adsorbent , but i s als o inlluence d l o alarg e extent b y th e desorbent . Wit

h 1-hexanol . fo

r example , only on e isomer.cihe r

in- o r p-cresol , ca

n be isolate d at apurit y o f ca . 99 % i

n asingl e operatio n ( 1 column) ; th e purit

y o f th e othe r isome r obtaine d i s only ca . 91% . Wit

h 1-pentanol , however , a mixture containin g ca . 69 % m-creso l an d3 1 % p-creso l ca

n be separate dint o a

n extrac t contain

in g 98.9 % ofp-crcso l an daraffinat c containin g 99.2 % of m-creso l i

n asingl e operatio n [93] . Phenoli c impuritie s presen t i n the creso l feed , e.g. , o-cresol , o-ethylphenol , 2,4- , 2,5- , an d2,6

- xylenol , migrate int o th e m-creso l durin g th e ad

sorptiv e separation ; hence , onl y pur e p-creso l ca n b e obtaine di

n on e operatio n i

f thes e impuri

tie s ar e presen t

in significant

quantitie s [93] . Othe r Methods . Th e separatio n o fm-/pcrcso l mixture s b

y azeotropi c distillatio n wit h benzyl alcoho l [242] o r

by countercurren t

extrac tio n wit h selectiv e solvent s (aqueou s methanol

gasoline ) [243 ] ha s acquire dn o practical impor

tance . Thi s als o applie s t o dissociativ e extractio n an ddistillatio n processe s tha t exploit Ihc higher dissociatio n constan t

(higher acidity ) of///-creso l i n relatio n t o tha t

o f p-cresol . Dissociativ e ex tractio n use s system s consistin g of aqueou s so diu mhydroxid e solutio n [244] , [245] , aqueou s trisodiu mphosphat e solutio n [246] , o r aqueou s aminoethano l solutio n [244] an da n organi c sol

vent , e.g. , benzene , hexane , o r toluene , b

y whic h th e p-creso l i s isolate di

n amultiste p extraction . I n dissociativ e distillation , a n amoun t of sodiu m hydroxid e solutio n equivalen t to th e m-creso l conten t i s adde dt o th e mixture an dthe p-creso l i s distille dthroug h acolum n wit h alarg e amoun t o f water vapo r a s a n azeotrop e [247] . 1.5.2 . Separatio n vi

a Additio n Compounds m-Creso l an dp-creso l for madditio n com pound s wit

h anhydrou s calciumbromide ; th e compoun dformedwit

h p-creso l ha s the highe

r thermodynami c stability . I f am-/p-creso l mix

ture i n toluen e i s heate dto 10

0 " C wit h 1 mo l of calciumbromid e pe r

mol e of p-cresol , the pre cipitat e tha t

i s filtere dof

f afte r ca . 8 h consist s practicall y only o f th e adduc t

o f p-cresol , while th e m-creso l conten t

of th e mothe r

liquo r i s cor respondingl y higher . I f

th e p-creso l adduc t

i s then decomposed , e.g. , b

y heatin g to 20

0 °C , p creso l wit h apurity o f

ca . 9 8 % i s obtained , to gether wit h reusabl e calciumbromid e [248] . Pur e ///-creso l ca

n b e isolate dfro

mth e mothe r

liquo r rich i n m-isome

r b y selectiv e adduc t

formation , e.g. , wit h sodiu macetat e [249 ] o r

ure a[250] . Pur e m-creso l ca

n als o b e obtaine dfro

mth e mothe r liquo r afte r coolin g t o ca . 0 t o - 5 ° C an daddin g calciu mbromide . Unde r

thes e kineticall y con trolle dconditions , th e mai n produc t i s th e mcresol-calciu mbromid e adduct , th e subsequent decompositio n o f

whic h give s m-creso l [251] . I

n adduc t formatio n wit

h exces s calciumbromid e at 25-3 0 C C , the m-creso l conten t of th e mothe r liquo r i s directl y rendere dpracticall y free o f p isomer . Th e p-creso l fro

mth e adduc t

the n con tain s correspondingl y mor e m-creso l [252] . I t i s no t know n whether

thi s process , whic

h wa s de

velope dby th e Kopper s Co . an dha s many variants , i s bein g use

dindustrially . Lithiu mbro

mide , magnesiu mbromide , o r magnesiu mchlo

rid e ca n beaisedio.plac e of

calciu mbromide , bu t th e result s ar e les s satisfactor y [248]-[252] . Man y organi c nitroge n compound s reac t wit h in- o r p-creso l to for

mcrystallin e additio n compound s that

ca n be separate dfro

mth e reac tio n mixture an ddecompose dt o regenerate th e nitroge n compoun dan dth e respectiv e creso l iso

me r [24] . Benzidin e wa s formerl y considere dpar ticularl y suitabl e fo

r th e separatio n o f

in- an d p-creso l b y virtu e o f the'pos.itio n of

, an ddiffer

enc e between , the meltin g point s o f it s adducts ; however , no t

only th e carcinogeni c propertie s o f thi s compoun dbut

als o othe r

consideration s no w preclud e it s use . A more suitabl e an dprac tica l proces s i s on e i

n whic h benzylamin e a s the auxiliar y substanc e form s wit

h m-creso l a1: 1 adduct , whic

h ha s ameltin g poin t

of 39. 5 °C . Th e adduc t i s centrifuge dan dfractionate din tw o distillatio n column s operatin g a t different pres sure s (101. 3 an d11. 3 kPa)i n such amanne r tha t th e benzylamin e i s recovere da t th e to p o f

col

um n 1 whil e pur e m-creso l i s obtaine da t th e to p o f colum n 2 . Th e mothe r

liquo r i s distille di n th e same way , then pure p-crcso l i s isolate db y crystallizatio n fro

mth e m-/p-creso l mixtur e rich i n p-isomer

obtaine din thi s cas e at

th e to p o

f colum n 2 . Th e benzylamin e i s recycle d[253] . CTh e isolatio n of///-creso l vi ath e 1: 1 additio n cbjnpoun d wit

h ure ai s aproces s o f

som e indus

trial importance . Formerly , th e separate dadduc tP.5 9

I Vol
. A 8 Vol
. A 8
wa s decompose db

y healin g wil

h water . No

w i t i s decompose di

n th e organi c solvent

i n whic h th e adduc t ha s bee n formed . Th e procedur e i s a s follows : Ure a(1.2 5 mo l pe

r mol e o f m-cresol ) i s adde dt o a mixtur e o f

m-/p-crcso l (65:35 ; 2 part s b y weight ) an d toluen e (0. 5 part s b

y weight) a t

3 0 "C . Th e mixlur c i s coole d t o - 1 0 "C , centrifuged , an dwashe d wil h toluen e (0. 2 pan s b y weight) . Th e product , consistin g mainl y o f th e ure a adduct , i s iniroducc d int o toluen e (1. 5 part s b y weight) , heate da t 8 0 ° C fo r 1 0 min , an dfilteredhot ; almos t al l th e ure ai s thereb y heldback . Distillatio n o f th e filtrate give s toluene , whil e tha i of

th e residu e give s ( S 98% ) »i-creso l i n 89 % yield[254] . Advantag e ma

y be take n o f

adduc t forma

tio n betwee

n cresol s an dcertai n othe r phenol s wit h avie w t o effecting separation . Fo r example , m-creso l forms wit

h pheno l a

n adduc t wit h a meltin g poin t

of 25. 9 ° C [255] , whil e p-creso l form s a n adduc t wit h bispheno l A [isopro

pylidenedi(p-phenol) ] [256] . Furthermore , mcreso l give s wit

h 1,4-dioxane at

2 0 C C an d 110-13 0 MP aa

n additio n compoun dtha t ha s bee n propose dfo

r th e separatio n of

m-creso l fro mm-/p-creso l mixture s in whic h th e conten t o f m-creso l i s hig h [257] . m-Creso l ca

n be precipitate da s a

n additio n compoun dwit

h anhydrou s sodiu macetat e fro m m-/p-creso l mixture s (e.g. , i n th e ratio 65:35 ) i n a n organi c solvent

(gasoline , benzene , o r toluene ) at

20-4 0 °C . Th e precipitat e i s remove d fro mth e mother

liquo r an ddecompose di

n the same solven t

b y heatin g t o 80-9 5 °C ; th e sodiu m acetat e i s filtered . m-Creso l i s obtaine dfro mth e organi c solven

t a s atechnicall y pur e produc t (96-99%) . Th e yieldi s ca . 70 % [24] . Higher yield s (75% ) andimprove dm-creso l purit y (99.5% ) ar e sai dt o b e possibl e i f th e adduc t

i s decompose da

t roo mtemperatur e wit

h pola r sol

vent s suc h a s aceton e [258] . 1.5.3 . Separatio n vi

a Este r o r Sal t Formation Th e mothe r

liquo r enriche dwit

h p-creso l (e.g. , t o am-/p-rati o o f

35:65 ) fro mth e precipi

tatio n wit h sodiumacetat e ca

n reac t wit h oxali c aci d- wit h azeotropi c dewaterin g - to give th e semieste r o r diester , whic h i s precipitate do n coolin g t o 2

0 °C . Th e ester

i s separate dan dthen hydrolyze db

y heatin g wit

h wate r at 85 % i n the presenc e of

th e respectiv e nonpolar

solvent . Th e oxali c aci dma

y b e precipitate do n coolin g an d Cresol s an d Xylenol s 4 3 recycled . Th e p-crcso l dissolve s in th e organi c solvent , fro

mwhic h i t

i s isolate dby distillation . Th e alternatin g us e of

bot h processe s separate s m - an dp-creso l almos t

entirel y [259] . Separatio n o f

th e cresol s vi ath e calciu mcresolates , i n whic h advantag e i s take n eithe r o f th e relativel y greate r solubility o f

th e calciu mp-cresolat e o r o f th e easie r

hydro

lyzabilit y o f th e m-crcsolal e wit

h superheate dsteam , i s unsatisfactory an dha s n o practica l importance . 1.5.4 . Separatio n b

y Nuclear Substitutio n Partia l separatio n of

cresol s i s possibl e b

y takin g advantag e eithe r

of th e lowe r solubilit y o f p-cresolsulfoni c aci di

n sulfuri c aci d[24] , of

th e more rapi dformatio n of m-cresolsulfoni c aci d durin g sulfonatio n [260] , o r of th e fact tha t th e rat e o f hydrolysi s o f

m-cresolsulfoni c aci di s faste r than tha t

of p-cresolsulfoni c aci d[261] . Th e last-mentione ddifferenc e form s th e basi s o f th e Bruckner

process , th e continuou s operatio n of which i n areactio n tower

i s describe din [262] . A large-scal e industria l process , e.g. , usedby Sumitom o in Iapan_an d Baye r in th e Federa l Republi c o f

Germany , comprise s th e separatio n o f m - an dp-creso l vi ath e di-ferf-buty l deriva

tives . In thi s technique , th e m-/p-creso l mixture react s wit h u p t o 2 mol of

isobuten e pe r

mol e of creso l i n th e presenc e o

f acidi c catalyst s (sulfuri c acid) . Th e resultin g alkylate dproduc t consist s mainly o f 2,6-di-/er.-butyl-p-creso l (bp 147° C at 2.67 kPa ) an d2,4-di-.er.-butyl-m-creso l (bp 167° C a t 2.67 kPa) , whic

h ar e easily separate d b y distillation , provide dtha t th e catalys t

ha s first bee n entirel y inactivated . Th e proces s als o yield s monobutylate dcresol s wit h boilin g point s of 124-129° C at

2.67 kP awhic

h ar e returne dt o th e alkylatio n reactor , an ddimers , trimers , an d possibly tetramer s (bp 12

5 ° C a t 2.67 kPa ) o f

iso

butene , whic h ar e remove dfro mth e system . m-Creso l o r

p-creso l an disobuten e ar e subse

quentl y recovere db y dealkylatio n o f th e di-/er/

- butylcresol s a t

ca . 200 ° C i

n th e presenc e of

suc h acidi c catalyst s as sulfuri c acid . Th e individual cresol s ar e the n further

purifie db

y distillation . Thei r purity may exceed99 % [263] , [264] . Con

tinuou s operatio n o f

th e butylation-debutyla

tio n proces s i s describe di

n [263 ] an d[265]-[267] . Th e proces s i s attractiv e no t simpl y becaus e i t give s a~ver

y hig h yieldo f

pure cresol , bu t

als o becau^, ' i t enable s 2,6-di-/er.-butyl-p-cresol , a widel y use d antioxidant , t o be produce dsimul

taneous]^ .P.6 0 4 4 Cresol s an d Xylenol s Vol
. A 8 I f unde r suitabl e condition s m-/p-creso l mix

ture s ar e chlorinate dwit

h sulfuryl chlorid e [268] , nitrosate dwit

h sodiu mnitrit e [269] , o r con dense dwit

h formaldehyd e [270] , m-creso l react s considerabl y faster , an dp-creso l wit h apurit y o f 96-98 % ca

n b e isolate dfro

mth e reactio n mix

tur e a s abyproduct . Thes e processe s are fre

quentl y exploite di

n practice .
1.6 . Qualit y Specification s an d Analysi s Cresol s an dthei r

mixture s ar e commerciall y availabl e i n awid e rang e of grade s an dpurities . They ar e characterize daccordin g t o th e follow

in g criteri a[271] , [272] :

- Content

of cresols, xylenols. and

oilier phenols, deter

mine dpreferabl y b

y GC , e.g. , accordin g t o ASTM 3626-8 0

- o-Cresol

content (mixtures) , determine dvi ath e crystal

lizin g poin t

o f th e cineol e adduc t

accordin g t o [271] , P C 17-67 ; o r m-cresol content (mixtures) , determine dvi ath e crystallizin g poin t

o f th e ure aadduc t

accordin g t o [271] , P C 16-67

- Crystallizing point, directl y o r afte r dryin g (pur e iso

mers) , e.g. , accordin g t o [271] , P C 10-67

- Distillation range (mixtures) , e.g. , accordin g i o [271] , P C 5-67 , o r DI N 5213 7 an d5213 9

- Residue on evaporation, e.g. , accordin g l o [271] , P C 7-6 7

- Residue on distillation, e.g. , accordin g t o [271] , P C 6-6 7 Specific grimly, e.g. , accordin g l o [271] , P C 2-67

- Color (colo r number) , e.g. , accordin g l o [271] , P C 1-67 , o r ASTM D 3627 • Water content, determine deithe r h y azcolropi c distilla

tio n wilh xylen e accordin g l o I)I:A N an dSTAK K ([271| , P C 3-67 ) o r

b y th e Kar l Fische r

melho d (AST M D 1631-80 )

- Content

of neutral oils, e.g. , a s determine daccordin g t o [271] , P C 4-67 , b y distillatio n afte r additio n o f

sodiu m hydroxid e solutio n (cresolal e formation )

- Content

of pyridine bases, determine deithe r accordin g t o [271] , P C 4-67 , b y titratin g ih e distillat e fro mth e neutra l oi l determinatio n with hydrochlori c acid , o r b y direc t titratio n wit

h perchlori c aci di n glacial aceti c aci d[272 ]

- Total sulfur content, e.g. , accordin g t o [271] , P C 22-6 7 (reductio n method )

- Acidity or

alkalinity, e.g. , accordin g l o [271] , P C 9-67 . b y titratio n agains t

pheno l re d

- Solubitiiv in sodium hydroxide solution, e.g. . accordin g t o [271] , P C 16-6

7 Specification s lai ddow n i n Britis h Standard s ar e a s follows : Ho

r o-creso l (crystallizin g poinl , fp, grad e A 30.3-31.O--C ; grad e B 29.3-30.3°C ; grad e C 28.3

- 29. 3 °C) , m-creso l (fp > 10. 5 °C) , an dp-creso l {fp

_ > 34.0°C ) i n B.S . 522:1964 ; fo r cresyli c aci do f

specifie d o-creso l conten t

(4 5 t o 90% ) i

n B.S . 517:1964 ; fo

r cresyli c aci do f specifie dm-creso l conten t (6 0 t o 39% , grade s A t o E ) i n B.S . 521:1964 ; an dfor so-calle drefine dcresyli c aci d (grade s A t o E with altogethe r 0.5 , 1.0 , 2.0 , 3.0 , o r

5.0 % water , pyridin e bases , an dneutra l oi l content ) i n B.S . 524:1964 . Maximal amount s o f impuritie s encountere d in commerciall y availabl e cresol s ar e usuall y n o more tha n 0.2 % water , 0.15 % pyridin e bases . 0.1 % neutra l oils , an d0.01 % sulfur . Syntheti c cresol s ar e practicall y fre e fro mpyridin e base s an dsulfur . Pur e cresol s ar e colorles s bu t ma y hav e afaintl y yellowis h color . Thei r mixture s sometime s hav e aslightly stronger tinge , rangin g fromyello w t o brown . o-Creso l i s produce dwit h apurity o f 99.2-99.9 % UPZ

30. 7 °C) , e.g. , for

EC N resin s (see p . 45) . Commonl y use dtechnica

l grade s hav e purity level s of

98.2-99 % (fp % 30.3

- 30. 6 °C) , ca . 96 % (fp a 29. 5 °C) , an dca . 94 % (fp a 28. 5 °C ) an dthu s correspon dt o grade s A . B , an dC o f

th e Britis h Standard . Fo r example , m-creso l i s sol dat

puritie s o f

99 % (fp a 11. 5 °C) , 98 % (fp a1 1 °C) , an d96.5 % (fp a 1 0 °C) . p-Creso l usually ha s apurity o f 99 % (fp a 3 4 °C) . Grade s wit

h apurity o f

ca . 95 % (fp a 3 1 °C ) an dca . 65 % ar e als o available . Th e mai n impurity i s m-cresol . Technica l creso l mixture s ar e usuall y classifie daccord

in g t o thei r

m-creso l content , whic h i s betwee n 20 an d7 0 % . Withi n this range.-man y different grade s ar e supplied , de

pendin g o n th e manufacturer-ao 4 th e customer' s require

ments ; ther e ma

y als o b e substantial ' difference s betwee n the mo n th e basi s o f

phenol s (pheno l itself

, o-cresoi . pcresol , xylenols , 2-cthylphenol , an dothe r alkylphenols ) tha t ar c additionall y present , a s wel l a s othe r impuritie s (water , pyridine , neutra l oils , an dsulfur compounds) . Thus , ther e ar e creso l mixture s containin g u p l o 50 % phe

nol , o r almos t 50 % xylenol s an dothe r alkylphenols . o r whic h hav e atota l creso l conten t o f onl y ca . 30% ; normall y th e latte r lie s betwee n 6 0 an d90% . m-/p-Crcso l mixture s obtaine db y chlorotoluen e hydrolysi s o r fro mih e cymene creso l proces s ar e distinguishe db y thei r hig h m-creso l con ten t (70 % an d60% , respectively ) an db y thei r hig h tota l conten t o f cresol , normall y £ 99% . 

### 1.7 . Handling , Storage , an d Transportatio n Th e cresol s ar e corrosive , an dtoxi c if ab

sorbe dthroug h th e ski n (se e Chap . 4) . Wor k wit h cresol s shoul db e carrie dou t in close dappa ratu s wherever

possible . Th e room s mus t b e wel l ventilated , an dprecautions , suc h a s th e us e of airlock s an dth e ga s compensatio n technique , mus t ensur e tha t

creso l vapo r

o r dus t canno t b e inhale db y personnel . Th e fundamental criterio n rf th e effectivenes s o f

all suc h precaution s i s th e MA K valu e o r TLV , whic

h in 1984 wa s fixeda

t 5 pp m(2 2 mg/m 3 ) fo

r al l creso l isomer s an d isomer mixtures . Thi s leve

l correspond s t o th eP.6 I

Vol
. A 8 odor threshold . A t

highe r concentrations , e.g. , resulting fro

moperationa l disturbances , suitabl e respirator s mus t

b e worn . I n addition , person s handlin g creso l mus t

alway s hav e adequat e ey e protectio n and , if

necessary , bod

y protection , e.g. , a s provide dby . polychloropren e o r PVC [polyviny l chloride) ] gloves , lon g aprons , full y protectiv e suits , etc . Furthe r recommendation s o h th e handlin g of

cresol s an dxylenol s ma

y b e foun di n [273]—[276

] an di n th e safet y dat asheet s o f creso l manufacturers . Stee l vessel s ar e suitabl e fo

r storage . Th e dis

coloratio n tha t

take s plac e o n storag e i s pro mote db y elevate dtemperatures , light , oxygen , water , an dcatalysts , e.g. , by dissolve diro n o r copper . I f th e produc t

i s require dto remai n colorles s fo

r a s lon g a s possible , i t

i s bes t t o us e tank s of stainles s stee l (V4A ; AIS I 316Ti) . If ex ceptiona l colo r stability i s required , th e produc t shoul dals o b e store dunde r nitrogen . Acces s o f moistur e mus t b e prevented , sinc e cresol s absor b wate r readily . Bot

h o-creso l an dp-cresol , whic h ar e solid s a t roo mtemperature , hav e t o b e han

dle dat atemperatur e highe r

than thei r crystalliz

in g points . Cresol-ai r

mixture s reac h th e lowe

r explosive limi t

a t ca . 7 6 ° C in th e cas e of

o-creso l an dat ca . 8 3 ° C in thos e o f

m- an dp-cresol ; therefore , if

th e storag e temperatur e exceed s 7 0 ° C o r 7 5 °C , respectively , th e ga s spac e mus t b e rendere diner

t wit h nitrogen . Storag e practic e must compl y wit

h local regulations . Th e storag e coniaincr s mus t

be teste dregularl y fo

r sound

nes s an dfreedo mfromleaks . A s the cresol s ar e classifie da s waterpollutants , measure s suc h a s th e provisio n o f

tan k basin s mus t

b e take n t o preven t creso l fro menterin g th e soi l o r drains . Cresol s ar e transporte di n heatabl e tan k cars , i n tan k trucks , o r

in stee l drum s wit

h acapacit

y o f ca . 200 L . Th e containe r

mus t bea r th e appro priat e hazar dwarning s i n complianc e wit h th e regulations . Fo r

unloadin g an dsampling , se e [275] . Transportatio n i s subjec t t o th e following regulations : Internationa l se atranspor t (IMD G Code ) an dinter

nationa l ai r transpor t (IATA-DGR

) fo r o- , m-, an dp creso l an dcreso l mixtures : Class 6.1 , UN-no . 2076 , pack

ag e grou p II ; fo r cresyli c acids : class 6.1 , UN-no . 2022 , packag e grou p II . Fo r transpor t o f o-, m-, an

dp-cresol, creso l mixtures , an

dcresyli c acid s o n Europea n road s (ADR ) an d railway s (RID) : clas s 6.1 , no . 14b , fro mJanua

r y 1 , 1986 . A s regard s transportatio

n o n Europea n waterway s (ADNR) , o-, m-, an

dp-creso l an dcreso l mixture s belon g t o class 6.1 , no . 22n

, an dcresyli c aci dt o class 6.1 . no . 22. Th e ADN Rclassificatio

n i s i o b e merge d wit h ih e ADR/RI D classificatio

n i n 1986 . Cresol s an d Xylenol s 

### 4 5 National regulations: Unite

d State s (DOT-CF R49 ) fo r o- , m-, p-creso

l an dcreso l mixtures : Corrosiv

e material / U N 2076 ; fo r cresyli c acids : Poiso

n B/U N 2810 . I n th e Federa l Republi c o f German y class 6.1 , no . 14b, i

s vali d fro mJanuar y 1 , 1986 , t o th e transpor t o f o-, m-, an

dp cresol, creso

l mixtures , an

d cresyli c acid s b y roa d(GGVS ) an drai l (GGVE) . Cresol s ar e liquid s tha t

ar e partl y miscibl e wit h wate r an dhav e flash point s o f

80 - 90 °C . A s such , they are , therefore , classifie din th e Federal Republi c o f

German y an din Wes t

Berlin a s belongin g t o grou p A , hazardclas s III , accord

in g t o th e regulation s fo

r th e storag e o f

flamma

bl e liquid s (Verordnun g iiber di e Lagerun g brennbare r

Fliissigkeiten , VbF) . I n th e Unite d States , m - an dp-creso l belon g t o Category 1 o f th e NFP A 704M fire hazardclassificatio n sys tem . Wate r

fog , foam , dr

y chemica l extinguish

ers , an d- for

smal l fires - carbo n dioxid e ar e suitabl e fo r fire fighting. In th e Federa l Republi c o f Germany , VD E Specificatio n 016 5 place s th e cresol s i n Ignitio n Grou p G 1 . 

### 1.8 . Use s Mos t o f th e o-creso l manufacture din Europ e i s chlorinate dt o 4-chloro-o-creso l (PCOC) , th e startin g materia l fo

r th e chlorophenoxyal

kanoi c acid s 4-chloro-2-methylphenoxyaceti c aci d(MCPA) , 2-(4-chloro-2-methylphenoxy)

- propioni c aci d(MCPP) , an dy-(4-chIoro-2-meth

ylphenoxy)butyri c aci d(MCPB) , whic h ar e im

portan t a s selectiv e herbicides . A considerabl y smalle r proportio n i s nitrate dt o 4,6-dinitro

o-creso l (DNCO) , which ha s both herbicidal an d insecticidal properties . Highl y pur e o-creso l i s increasingl y pro cessed , especiall y i n Japan , t o epoxy-o-creso l novolak resin s (EC N resins) , whic h ar e use da s sealin g material s for

integrate dcircuit s (chips) . o-Creso l (o f

commo n quality ) i s als o use dt o modif y traditiona l phenol-formaldehyd e resins . o-Creso l i s als o importan t a s aprecurso r

of variou s dy e intermediates , o f whic h th e mos t

im

portan t in term s o f

quantity i s o-cresotini c aci d (o-hydroxymethylbenzoi c acid ) produce db y th e Kolb e synthesis . Thi s aci dfinds furthe r us e in the manufactur e o f

pharmaceuticals , wherea s it s methy l ester s serv e a s dydftg auxiliaries . A n appreciabl e amoun t

o f o-creso l i s useda s asolvent , cithe r

directl y o r

afte r hydrogenatio n t o 2-methylcyclohexano l o_ , 2-methylcyclohexa

none . In th e for

mo f it s carbonat e ester , o-creso l

### 46 Cresol s an d Xylenol s Vol
. A 8 Vol
. A constitute s astartin g materia l in th e synthesi s o f coumarin . Th e alkylatio n o f o-creso l wit

h propen e give s carvacro l (3-isopropyl-6-methyl

phenol) , whic h i s use da s a n antisepti c an di

n fragrances . I n addition , small amount s of o creso l ar e useda s startin g material s in th e pro ductio n o f

various.*Antioxidants . m-Cresol , eithe r

pur e o r mixedwit

h p-cresol , form s astartin g materia l fo r such importan t

con tac t insecticide s a s 0,0-dimethyl-0-(3-methyl

4-nitrophenyl)thionophosphori c aci d(fenitro

thion ; Folithion , Sumithion ) an d0,0-dimethyl

0-(3-methyl-4-methylthiophenyl)thionophos

phori c aci deste r

(fenthion ; Baytex , Lebaycid) . I n addition , m-creso l i s neede di n th e synthesi s of pheny l m-toly l ethe r

(m-phenoxytoluene) , whic h afte r oxidatio n t o m-phenoxybenzaldehyd e serve s a s abuildin g bloc k

i n th e productio n o f

insecti

cide s o f th e pyrethroi dtype . Pur e m-creso l ha s considerabl e importanc e in th e productio n o f

fragranc e an dflavor

sub

stances : it s isopropylatio n give s thymol , from whic h (-)-mentho l i s obtaine db y hydrogena

tio n an dseparatio n o f

th e isomers . 6-tertButyl-m-cresol , obtaine dby alkylatio n of mcreso l wit h isobutene , i s th e startin g materia l fo r th e perfum

e fixative mus k

ambrette . Th e condensatio n o f

6-rerf-butyl-m-creso l wit h sul

fu r dichlorid e give s 4,4'-thiobis(6-rerf-butyl-m

cresol) , an importan t

antioxidan t

fo r poly

ethylen e an dpolypropylene . Furthe r antioxi

dant s ar c produce d fro

m6-fMV-bulyl-m-crcso

l b y condensatio n wit

h butyraldehyd e o r

croton aldehyde . I n Japan , m-toluidin e i s produced , o n demand , b y aminatio n of m-cresol . Th e 4-chloro-m-creso l obtaine dby selectiv e chlorinatio n o f

m-/p-creso l mixture s finds us e a s adisinfectan t

an dpreservative . 2,4,6-Trinitro

m-creso l can b e use da s an explosive . p-Cresol , pur e o r

mixe dwit

h m-creso l (se

e p . 43) , i s use dmainl y t o produc e 2,6-di-ferf

butyl-p-creso l (BHT) , anonstainin g an dlight

resistan t antioxidan t

wit h awid e rang e o f

ap plications . 2-Alkyl-p-cresol s obtaine db y th e monoalkylatio n o f

p-creso l i n th e orth o position , e.g. , tert-butyl-, cyclohexyl- , methylcyclohexyl- , a-methylbenzyl- , o r

nonyl-p-cresol , can b e con dense dwith formaldehyd e o r sulfu r dichlorid e t o giv e 2,2'-methylene

- o r

2,2'-thiodiphenols , whic h ar e als o importan t

a s antioxidants . 2,6-Dicyclo

pentyl-p-cresol , obtainabl e by dicyclopentyla

tio n o f p-cresol , i s aver

y effective antioxidant . Couplin g o f

2--er.-butyl-p-crcso l wit

h diazotize d 4-chloro-2-nitroanilin e yield s Tinuvi n 326 , an absorbe r o f UV light , whic h finds use , e.g. , fo r polyethylen e an dpolypropylen e films an dcoat ings . I n th e fragranc e industry , p-creso l i s usedto obtai n p-cresolcarboxyli c aci dester s and , partic

ularly , p-creso l methy l ether , mos t o f whic h i s use di n th e productio n of

anisaldehyde . Lik

e o cresol , m - an dp-creso l ar e use da s component s of variou s dyes . A n importan t

fieldo f applicatio n fo

r tech

nica l creso l mixture s i s the productio n of modi

fiedphenoli c resin s b

y condensatio n wit

h form

aldehyde . Th e suitabilit

y an dpric e of

creso l mixture s fo

r thi s purpos e depend s o n thei r con ten t o f m-cresol , th e mos t

reactiv e o f

th e thre e isomers . Creso l mixture'* , are highl y importan t a s solvent s fo

r syntheti c resi n coating s (wir e enamels) . m-/p-Creso l mixture s fre

e o f th e o-isomer

ar e use dt o produc e neutral phosphori c aci dester s (tricresy l phosphate , dipheny l cresy l phosphate) , whic h findus e a s fire-resistant hydrauli c fluids , a s additive s in lubricants , a s ai r filter oils , an da s flame-retardant

plasticizer s for

PV C an dothe r plastics . Th e bactericidal an dfungicida l propertie s of cresol s enabl e the mt o b e use da s disinfectant s in soap . Syntheti c tannin g agent s o f commercia

l importanc e ar e obtaine db y th e condensatio n o f formaldehyd e wit

h cresolsulfoni c acid s an dby th e sulfonatio n o f

novolak s obtaine dfro

mcre sols . Crud e cresol s ar e use da s woo dpreserva tives . Creso l mixture s ar c als o used i n ore flota

tio n an dfiber

treatment , a s metal degreasin g an d cuttin g oils , a s extractin g solvents , an da s agent s fo r removin g carbonizatio n deposit s fro min

terna l combustio n engines . Methylcyciohexano l an dmethylcyclohexanon e produce dby hydroge

natio n of cresol s ar e usedi

n th e pain t

an dtextil e industries . 

### 1.9 . Economi c Aspects Th e combine dtota l outpu t o f creso l o f th e Unite dStates , Wester

n Europe , an dJapa n in 198 4 wa s estimate dt o b e 2200001 : Syntheti c creso l ca . 140000 1 Cresol fro

m coa l U r ca . 55 000 1 Cresol fro

m spentrefiner

y caustic s ca . 2

5 000 1 Tota l £ ca . 220000 1 Abou t 65000 1 wa s ^produce d in th e Unite d Stales , abou t

9 5 000 1 in . Wester

n Europe , and abou t 60000 1 in Japan . Approximatel y hal f of 

# f

si ; _ 3 th e tot ; th e pu r Abou t manuf i Th e spen t r conten t taine d whic h : were cr tar s pr e cresol s i n So u accpu n cresols . Th e ove r th e especial shutdo \ noco , K thus , to [43] . N e eratio n Genera l ducin g c scal e th a capacit y (Gener a an dGE :


### 2 . Xv L

O H 

# 60 CH .

O K 

# 3 rP.6 3



### Vol
. A 8 finds use , e.g. , for m e films an dcoat - , p-creso l i s use dt o ; ester s and , partic

mos t o f which i s saldehyde . Lik

e o-

_a s component s o f plicatio n fo

r tech

oductio n of

modi

nsatio n wit

h form

i dpric e of

creso l I end s on thei r

con activ e o f th e thre e highl y importan t .i n coating s (wire o f the o-isome

r ar e .phori c aci dester s cresyl phosphate) , i t hydrauli c fluids , i r filter oils , an da s

_ r PVC an dothe r | cida l propertie s o f a s disinfectant s i n u s o f commercial i e condensatio n o f oni c acid s an db y .btaine d fro

mcre a s woo dpreserva - > use di n or e flota

- •ta l degreasin g an d [ ents , an da s agent s J deposit s fro min

cthylcyclohcxano l duce db y hydroge

l e pain t an dtextil e

|u t o f creso l o f th e •pe , an dJapa n i n ! 00 0 t : ca . 14000 0 t ca . 55O0O t ca . 2 5 00 0 t ca . 22 0 00 0 t ce d in th e Unite d ;ter n Europe , an d | roximatel y hal f

o f 

# r

m



# I Vol
. A 8 the total creso l outpu t

i s processe di

n th e for mo f th e pure isomers , an dth e res t a s isomer mixtures . About 30 % o f th e tota l outpu t

i s usedb

y th e manufacturer s themselves . The abov e figure s for

creso l fro mcoa l tar an d spen t refinar y caustic s refe

r onl y t o th e creso l content . The y d o no t

includ e th e xylenol s con taine di n th e ra w materia l (30000-400001) , whic h t o some exten t

ar e sol da s thoug h the y wer e cresol . Th e ta r

cresol s ar e obtaine dfro m tar s produce di n Eastern Europ e an dfro mcrud e cresol s resultin g fro

mth e gasificatio n of

coal i n Sout h Africa . Thi s proportio n probabl y account s fo

r ca . 25 % o f

th e tota l outpu t

o f ta r cresols . The tota l outpu t

o f creso l ha s no t

increase d ove r th e las t te n years . Substantia l overcapacity , especiall y fo r o-cresol , ha s led t o th e (temporary ) shutdow n of

plant s i n th e Unite dState s (Co

noco , Koppers , an dDiamon dShamrock ) and , thus , t o adecreas e i n capacity o f ca . 5 0 000 t/ a [43] . Nevertheless , th e capacity remainin g i n op eratio n i s no t

bein g usedfully , partl y becaus e Genera l Electri c in th e Unite dState s i s no w pro ducing o-creso l i n plac e o f

2,6-xyleno l o n alarger scale tha n before an dpartl y becaus e ne w o-creso l capacit y ha s been installe di n th e Netherland s (Genera l Electric ) an di n Japa n (Nippo n Creno l andGEM-Polymer) .


### 2 . Xylenol s [i]-[3 ] Xylenol , dimethylphenol , C 8 H 10 O , M, 122.166 , occur s i

n si x isomeri c forms :
O H O

H O H
CH , 2.3-Xj**l«no l 2.4-X7lw_o l 2,S-Xyl<ao l 2.3-<___-ot_*7'p_.«no

l 2,4-d-____tbylpl_*nol 2.5-<___nth*-lph«aol [528-33-0]

[103-87-9]

[98-87-4] O H O

H O H

> ^ T^ S HsC^^CH ,

CH , 2,a-X*f_«no

l 3.4-Xj*i«__o

l 3,5-Xjrl«_o l 2,8-d___Mt__7ip_t«__o

l 3.4-dimtUijrlp-iaao l 3.S-<_i_o»t_i*riphe_*o l [878-28-1]

[83-83-8]

[108-88-9] Th e numberin g o f

th e substituent s normall y an dcorrectl y begin s fromth e O H group ; bu t i s 

### Cresol s an d Xylenol s 4 7 occasionall y (erroneously ) starte dfro mth e methy l group : 2,4-xyleno l ca n b e referre dt o a s 1,3,4-xylenol , 4-hydroxy-m-xylene , o r 4-hydro

xy-1,3-dimethylbenzene . Xylenol s ar e present , e.g. , i n th e essential oil s o f variou s conifers , in tea , i n tobacc o an dtobac

c o smoke , i

n roaste dcoffee , an din variou s smoke dfoods . In many cases , they contribut e t o th e flavo r o f thes e products . Fro mth e standpoint

o f economics , th e mos t importan t isomer i s no w 2,6-xylenol , of

which coa l ta r contain s onl y arelativel y smal l amoun t an dwhic h i s produced , therefore , almos t entirel y by syntheti c means . 2.1 . Propertie s [l]-[3 ] Th e xylenol s ar e colorles s crystallizin g com pound s tha t

ar e solubl e in alcohol , acetone , an d i n man y othe r

organi c solvents . The y ar e les s solubl e in wate r

tha n th e cresols . Excep t fo r 3,5-xylenoI , thei r

acidit y i s likewis e lower

than tha t o f th e cresols . They ar e solubl e in aqueou s sodiu mhydroxide , bu t

t o different

extents , de

pendin g o n th e structure . Thei r chemica l behav

io r i s simila r t o tha t o f th e cresols . Physica

l dat a ar e presente di n Tabl e 4 . Fo r dependenc e o f

th e thermodynami c dat ao n temperature , see [8] , [277]-[279] . 

### 2.2 . Isolatio n Wit h regar dt o th e formatio n o f xylenol s in variou s therma l crackin g processes , se e Sectio n 1.3 . Xylenols , wit

h th e cresol s an dothe r

phenols , ar e isolate dfro

mhigh-temperature , low-tem

perature , an dLurg i pressur e gasifie r coal tar s (se e Sectio n 1.3.1 ) an dfromspen t refiner y caus tic s (see Sectio n 1.3.2) . Th e resultin g crud e phe

nol s (cresyli c acids ) contai n al l si x xylenol s in amount s tha t

diffe r greatl y accordin g t o th e ra w materia l an dcondition s o f formatio n (see Tabl e 3) . Moreover , th e ratio o f th e xylenol s them

selve s differs . I n xylenol s fro mspen t refiner y caustics , 2,4-xyleno l generall y predominates ; be

side s this , th e conten t

o f 2,5-xyleno l i s high , wherea s tha t

of$,5-xyleno l i s relativel y small [280] . Xylenol s frombituminou s coal ta r ar e characterize db y thei r

hig h conten t

of 3,5

- xylenol . Th e averag e isomer rati o o f bituminou s coa l ta r xylenol s i s given i n [281] ; for example , a skele y 

# KIRK-OTHME R

Yor k

Yor k RCE R 

# ENCYCLOPEDI A O F

CHEMICA L TECHNOLOG Y
THIR D EDITIO N

A WILEY-INTERSCIENC E PUBLICATIO N 

## Joh n Wile y & Sons NE W YOR K• CHICHESTE R • BRISBAN E • TORONT OPag e Lin e

Copyrigh t ©

197 8 b v Joh n Wile

y & Sons , Inc . Al l right s reserved . Publishe

d simultaneousl y i n Canada . N o par t o f thi s boo k

ma y b e reproduced b

y any means , no r transmitted , no r translate d int o a machin e languag e withou t th e writte n permissio n of th e publisher . Library o f Congres s Catalogin g i n Publicatio n Data : Mai n entry unde r title : Encyclopedi a o f chemica l technology . A t hea d o f title : Kirk-Othmer . " A Wiley-lnterscienc e publication. " Include s bibliographies . 1 . Chemistry , Technical—Dictionaries . I . Kirk , Raymon d Eller , 1890-1957 . II . Othmer , Donal d Frederick , 1904 - III . Grayson , Martin . IV . Eckroth , David . V . Title : Kirk-Othme r encyclopedi a o f chemica l tech - nology . 

# €

TP9.E68 5 197 8 66O*.03 ISB N 0-471-02037- 0 77-1582 0 Vi i I I X XX I XXV I XXVII I XXI X 12 0 12 0 12 0 12 0 12 0 j 12 0 12 0

- 12 0 1 62 3 I 32 3 ! 62 4 | 75 3 ! 93 2 ! 96 2 1 2 fro m

1 3 2 3 fro m b 3 fro m fc 6 Tabl e 3f t Tabl e 3 d Tabl e 3( t Tabl e 3 d Tabl e 3 d Tabl e 3 d Tabl e 3 d Tabl e 3 d re f 3 bo t 3 1 4 1 1

Pag e 1 7

Printe d i n th e Unite d State s o f Americ aP.6 6 

## CurVSjuHTE D Vol . 2 2 TA RAN D PITC H 59 3 Cresylic Acids . Th e highe r boilin g cresyli c acid s ar e mixture s o f cresol s or xylenol s Wit h highe r boilin g phenol s (se e Phenol ; Alkylphenols) . Thei r mai n use s ar e i n phe

nol-formaldehyd e resins , solvent s fo r wire-coatin g enamels , a s metal-degreasin g agents , froth-flotatio n agents , an dsyntheti c tannin g agent s (se e Tabl e 16) . Statistic s d o no t distinguis h betwee n th e variou s grade s o r betwee n cresyli c acid s derive dfro m coa l ta r or petroleu mor

mad e syntheticall y (se e Phenoli c resins) . Naphthalene . Unti l th e 1960s , th e principa l outle t fo r naphthalen e wa s th e pro ductio n o f phthali c anhydride ; however , mor e recently , o-xylen e ha s replace dnaph

thalen e a s th e preferre dfeedstoc k (se e Phthali c acids) . Today , onl y c a21.3 % o f th e phthali c anhydrid e mad e in th e Unite dState s i s derive dfro mnaphthalene ; in Western Europe , c a10% ; an di n Japan , c a30% . I n Europe , th e mai n use s fo r naphthalen e ar e fo

r th e manufactur e of/3-naphtho l an dfo r dyestuf f intermediate s (se e Dye s an ddy e intermediates) . Creosote . I n coal-ta r

refining , th e recovery o

f ta r chemical s leave s residua l oils , includin g heav y naphtha , dephenolate dcarboli c oil , naphthalen e drai n oil , was h oil , straine danthracen e oil , an dheav y oil . Thes e ar e blende dt o giv e creosote s conformin g t o particula r

specifications . Creosot e oil s ar e by fa

r th e mos t widel y use dtimbe r

preservative s (se e Wood) . Thi s us e date s bac k

t o 1850 . Th e 198 1 U.S . consumptio n i s estimate da t <500,00 0 t . Fo r th e treatmen t

o f railway tie s an dmarin e pilings , th e Bethel l or Full-cel l proces s i s preferred . Th e timbe r t o b e treate di s charge dt o apressur e cylinder , whic h i s evacuate dt o extrac t

th e ai r fromth e woodcells . Th e cylinde r i s the n fille dwit

h ho t creosot e an dth e pressur e increase dt o 0.8- 1 MP a(c a8-1 0 atm ) t o forc e th e oi l int o th e cells . Whe n uptak e o f th e oi l ha s ceased , residua l creosot e i s draine dfromth e cylinde r an dth e treate dtimbe r

i s briefl y subjecte dt o avacuu mbefore discharge . Fo r th e treatmen t

o f telegrap h an dtransmissio n poles , fenc e posts , an dfar m buildings , wher e aclean oute r surfac e i s desired , th e empty-cel l proces s i s generall y used . Th e Ruepin g proces s employ s a n impregnatio n cycl e in whic h th e timbe r i s firs t subjecte dt o amoderat e ai r pressur e t o compres s th e ai r in th e cell s befor

e th e cylinder i s charge dwith ho t

creosote . Th e pressur e i n th e cylinde r i s increase dt o forc e th e oi l int o th e woo dcells . Whe n n o mor e oi l i s absorbed , th e pressur e i s released , allowin g th e ai r insid e th e timbe r

t o expan dan dforc e th e creosote out ; aprotectiv e filmremain s on th e cel l wall . After

dischargin g surplu s creosote , th e treate dtimbe r i s evacuate d

Tabl e 16 . Us e U.S . Distributio n o f Creso l an d Cresyli c Acid s Uses , 1976- * % phosphat e ester s solvent s wire-coatin g enamel s antioxidant s phenoli c resin s cleanin g compound s froth-flotatio n agent s miscellaneou s expor t

" Kef . 72 . 2 0 1 5 1 5•AI R npan y sour i 

# Encyclopedi a of

Chemica l Processin g an d Desig n
EXECUTIV E EDITO R ASSOCIAT E EDITO R 

# Joh n J . McKett a

Willia m A . Cunningha m

. LUDWI G suitin g Engineers . In c c . Louisian a ( MARCE L DEKKER , INC . " NE W YOR KAN D BASE LCOPYRIGHT © 197 6 b y MARCE L DEKKER . INC . AL L RIGHT S RESERVED . Neithe r thi s boo k no r an y par tma y b e reproduce d o r transmitte d i n any for m o r by an y means , electroni c o r mechanical , includin g photocopying , microfilming , an d recording , o r b y any informatio n storag e an d retrieval system , withou tpermissio n i n writin g fro m th e publisher . MARCE L DEKKER . INC . 27 0 Madiso n Avenue , Ne w York . Ne w Yor k 1001 6 LIBRAR Y O F CONGRES S CATALO G CAR D NUMBER : 75^064 6 ISBN : 0-8247-2451- 8 Currentprintin g (las tdigit) : 1 0 98765432 1 PRINTE D I N TH E UNITE D STATE S O F AMERIC A 

# itern a

- • C . ADA M •.••... n o l ih e B

< .".lusiries . In c "* . • * M . No w V

- M S . AHM A ;':CMde[ U ;t_ u

. ..in Su n O u C Laiunor . \ ALLAWA l \_n w Diric. o ••a i Refiner } -in . -*aki*t_

n ME D H.A M *.i ; Superv i

... l Ucr.cri i
• • 4.P t .'.MTHON '
• r Depart *
c ; !_•_ . • .* . M L'r . M.H*...--. . I ; -*'fl*.'.••'M M

-. 0 .V.

- .;.i.q i

AL U L : ;

:••-.:> I' v

*••..*.•.•_•.
. • * n A BA l

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• ' r '. .V.. . «F M BAL t

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. ^Ar t BAP T •'".••..•e m ••-*•• • M-.-M , .:. u l r \

\ri*t<-r * O. 1 «•-*•••* • •*'•**• • P.6 9

2.1 2 Cracking , Therma l Creso l

Nelson , W . L. , Oil

Gas J., 55(15) , 13 9 (Apri l 15 , 1957) . Nelson , W . L. , Petroleum Refinery Engineering, 4t h ed. , McGraw-Hill , Ne w York , 1958 . "Nelso n Cos t

Indexes, " Oil

Gas J., 73(H), 13 4 (Apri l 7 . 1975) . Sachanen , A . N. , Conversion of Petroleum, 2n ded. , Reinhold , Ne w York , 1948 . Staff , Hydrocarbon Process. Pet. Refiner, 41(9), 17 2 (1962) . Staff , Hydrocarbon Process., 47(9), 15 3 (1968) . Staff , Hydrocarbon Process., 53(9), 12 3 (1974) . 

### Stephens , M . M. , Petroleum Refining, Vol . 2 , Pennsylvani aStat e College, Stat

e College , Pennsylvania, 1941 . W . P . BALLAR D G . I . COTTINGTO N T . A . COOPE

R 

# Cr->, V / - , 

# Cresol s an d Cresyli c Acid s •Jf£ D

Cresols are monomethy l derivative s o f phenol . There are thre e creso l isomer s which diffe

r b y positio n of

th e methy l substituen t

a s ortho , meta , or

par a relativ e t o th e phenolic-O H group . Al l thre e isomer s ar e know n an deac h i s commercially important . Th e term s cresylic acid

an dtar acids historicall y hav e bee n applie dto the mixture o f pheno l homolog s recovere dfro mcoa l tar and/o r petroleum . Such mixture s typically contai n phenol , th e thre e cresols , th e si x xylenol s (dimethy l phenols ) alon g wit

h mino r amount s of

ethy l phenols , an dC 3 

### - an dC 4 

### - substitute dphenol s (trimethyl , ethyl-methyl , propyl , butyl , diethyl , methyl

propyl , etc.) . In moder n usag e th e ter

mcresylic acid

ha s generally evolve dt o designate mixture s containin g significan t amount s o

f tw o o r mor e o f th e alkyl-substituen t homolog s o

f phenol . It

i s mos t commonly applie dt o mixture s derive dfro m recover y of natura l origi n (coa

l o r petroleum) . Cresyli c aci dha s bee n definedi n on e instanc e [1 ] a s "mixture s of pheno l an dalkyl-substituted , mono-hydri c phenols , bu t

limite dt o phenoli c constituent s whos e normal boilin g point s are 230° C o r less. " However , i

t i s no t uncommo n t o exclude pheno l fro mth e cresyli c aci ddesignatio n in which cas e acrud e mixture migh t b e considere da s a mixture of pheno l an dcresyli c acid . Thi s practic e i s followedby th e U.S . Tarif f Commissio n in it s report s [2] . Th e dominan t

commercia

l source s of

cresol s an dcresyli c acid s are natura l sources ; coal tar

an dpetroleum . Thes e sources , supplemente db y direc t synthesi s o f

variou s isomers , compris e all of th e currentl y significan

t com mercia l supply . Commercia

l productio n of

syntheti c cresol s bega

n i n th e late 1950s an dha s show n significan t growth . Substantia l increas e i n suppl y fro ma"new " natura l soprc e ma y b e comin g i n th e 1980s . Wit

h diminishin g domesti c crud e petroleu mreserve s an da government

polic y o f avoidin g excessive dependenc e o n foreig n crud e pe -P.7 0



### Cresol s an d Cresyli c Acid s 21 3

troleum , emergin g technologie s are aimeda t conversio n o

f enormou s coa

l reserve s t o liqui dan dgaseou s fuels [9] . Th e recover y o f substantial commercia

l quantitie s o

f pheno l andcresyli c acid s fro mthes e "new " coal-base doperation s olTer s th e promis e o

f addin g major

increment s to curren t

supplies . I

f thes e coal

basedoperation s materializ e an dcoupl e wit h the separation s technolog y a s currentl y practice di

n th e coal-ta

r an dpetroleum-base dcresyli c aci dindustry , the y wil l ten dt o limi

t th e manufacture o

f specifi c isomer s viasynthesi s to thos e inadequatel y supplie db

y natura l sources .
D N R 

### Propertie s

r s r a i s i e 

### : h y l • 4 *ALt e 

### n t > m i n ri c ir e h e s a -if f
ra l ee trelat e in g I a pe Th e chemica l propertie s o

f cresols , xylenols , an dhighe r homolog s are substantiall y extension s o

f th e parent

homolog , phenol . Similarly , the physica l propertie s for

malogica l extensio n fro

mthe parent . Selecte

dvalue s fo

r cresyli c aci dconstituent s are give

n i n Tabl e l , i

n whic h the value s shown wer

e take n (excep t wher e otherwis e noted ) fro

mth e critically reviewedtabulatio n prepare d b y th e Manufacturin g Chemist s Associatio n research projec t [8] . Historica l Evolutio n o f Coke , Cok e Chemicals , an d Cresyli c Aci d Th e discover

y an dcommercia

l evolutio n o

f pheno l an dcresyli c acid s ha s followe dman' s ques t

fo r derivin g energ y fro

mfossi l fuels . Recover

y o f "ta r acids " fro mcoa l ta r comprise dth e earlies t

commercia

l sourc e o

f phenol , cresols , an dxylenols . Th e practic e o

f producin g cok

e b y carbonizatio n o

f coa l originate di

n Europ e i n th e 1600s fo

r th e purpos e o

f producin g aclean , convenient soli dfue l [3] . Cok e was first

successfull

y usedi n ablas t furnac e b y Abraha mDarb y i

n Shropshire , England , i

n 1707 . Abou t

th e tim e beehiv e oven s wer

e developed , th e usefulnes s o

f th e volatil e product s evolvedupo n heatin g coa l bega n to be recognized . I

n 179 2 ayoun g mechanica

l engineer , Willia

mMurdock , wa

s convince dthat

thes e volatil e product s coul db e utilize dfo

r illumination . Wit

h thi s convictio n h

e commence d5 year s o

f experimentatio n an dsucceededi n carbonizin g coa

l i n iro n retort s an dpipin g th e evolvedgase s int o hi s hom e an d worksho p fo

r illumination . Havin g demonstrate dth e practicalit y o f coa l ga s illumination , h

e convince dhi s employer , th e Boulto n an dWat t stea mengine factor y i n Birmingham . England , to install th e syste minjlia t factory . I

n 180 2 the firs t commercia

l tise o f manufacture d ga s wa

s undertake n whe

n the Soh o plant o f Boulto n an dWat

t was illuminate db

y ga s light s fuele

db y aproces s o

f Murdock' s design . Murdoc k ultimatel y ros e to be work s superintenden t an d becam e known a s "th e Fathe r

o f th e Ga s Industry. " I n th e fift y year s betwee

n 180 0 an d1850 , asignifican

t industr y evolved__ _ 4 ^

TABL E 1 Propertie s o f Cresyli c Aci dConstituent s (fro mRef . 8 unles s otherwis e noted )

Boilin g point : C C a t 76 0 mmH g C C a t 30 0 mmH g ° C a t IO O mmH g ' C a t 2 0 mmH g Freezin g point , ° C Liqui ddensit y a t 20C , g/ml J Specifi c heat , cal/ g a t

O' C Laten t heat , fusion . cal/ g • mo l Laten t h£at,*vSJJ«**j;ization , cal/ g • mo l a t

76 0 mmH g 'Densitie s o f

subcoole dliqui d Pheno l

181.83 9 150.9 5 120.7 0 85.3 2 40.9 0 1.076 7 0.54 8 275 2 10.92 0 o-Creso l

191.00 4 158.6 2 127.0 6 90.2 1 30.94 4 1.046 0 0.495 5 [II ] 309 5 10,80 1 .-.-Creso l

202.23 2 169.9 1 138.2 3 101.1 3 12.2 2 1.0340 9 0.472 7 [II ] 216 9 11,32 9 /.-Creso l

201.94 0 169.7 9 138.3 2 101.5 5 34.73 9 1.034 8 0.468 5 [11 ] 206 7 11,36 5 2, 6

201.03 0 166.8 8 133.5 4 94.6 8 45.6 2

363 3 10,64 1 2. 5
211.13 2 177.4 3 144.5 7 106.3 0 74.8 5 1.02 4
332 3 11.21 9 Xyleno l

2. 4 210.93 1 177.4 0 I44.6 S 106.5 7 24.5 4 1.0201 7 306 9 11.26 8 2, 3

216.87 1 182.6 8 149.3 4 110.4 9 72.5 7

475 0 11,31 0 3, 5

221.69 2 188.2 2 155.4 7 117.1 9 63.2 7 1.02 2 434 2 11,78 5 3, 4 226.94 8 193.0 7 159.9 8 121.3 8 65.1 1 1.03 5 314 0 11,87 1 O 1 C D 

### o (/ I C D

_ } 

### a. 

### _- _IresylicAcids



### o

- I C D I A O *•> !P.7 2

Cresol s an d Cresyli c Acid s 21 5



### aroun dcarbonizin g coa

l t o produc e manufacture dga s fo r ga s lightin g an dcok

e fo r agrowin g stee

l industry . Littl e or

no commercia

l attentio n was give

n t o utilizin g ta

r an dliquids . I

n fact , man

y cok e producer s gathere dthes e trouble

som e problem s into barrel s an ddumpe d the ma t sea . However , considerabl e attentio n wa

s pai dto thes e coa

l ta r liquid s b y chemist s durin g the period , particularl y i

n Germany , centerin g aroun dth e wor k o f Justu s vo n Liebig a

t Giessen . I n 1834 , Friedlie

b Ferdinan dRunge , achemis t wit h the Prussia

n Marin e Servic e i

n Berlin , discovere di

n coa l ta r oi l a n acidi c substanc e h

e calle d carboli c aci d[6] . Five year s later th e Frenc h chemist , Augus t Laurent , succeede di

n recoverin g pure pheno l fro mcoa l tar , an dwa

s first to nitrat e i

t to picri c acid . Aroun d184

0 aGerman chemis t

an dstuden t

o f Liebi g a t Giessen , A . W . Hofmann , becam

e intereste di

n th e volatil e product s obtaine db y heatin g coal . H c cam e to Englan di

n 184 5 t o becom

e professor

a t the ncwly-formc d Roya

l Colleg e o f Chemistr y wher e h e remaine dfo

r 2 0 years . H

e pursue dhi s idea s abou t coa l ta r a t the colleg e an dassignedsom e o f hi s student s the tas k

o f identifying its constituents . On e o f Hofmann' s student s wa

s Charle s Mansfield , wh o studie da

t the colleg e fro

m184 7 t o 1850 an di s regarde da s the founde r o f coa l ta r chemistry . Mansfieldha

dastron g desir

e to conver

t hi s researc h int o a business , an di

n thi s was encourage db

y hi s teacher

an dfriend , Hofmann . H

e ha dexamine di

n detai l th e ligh

t naphth afraction fro

mta r distillatio n and , b

y repeate ddistillation s an dsuccessive washe s wit h sulfuri c aci dan dcausti c soda , was abl e t o obtai n benzene , toluene , an dxylene . Mansfiel dwa s grante dapaten t o n hi s purificatio n proces s i n 1848 , an dthi s proces s wa s th e forerunne

r to th e coa l tar chemical s business . He promote dth e us e of benzene a s adry-cleanin g solven t and , wit h Hofmann , progresse dto th e manufacture o f nitrobenzen e an dthenc e t

o aniline , whic

h was to prov e importan t

late r i n the development

o f dyestuffs . Mansfielddiedtragicall y i n alaboratory fire i

n 1855 , but

i n afe w shor t year s h e made a n indelibl e mar

k on th e early histor

y o f coa l ta r chemistr y [4] . Another

o f Hofmann' s student s was W . H . Perkin wh o i n 185 6 wa

s attemptin g to synthesiz e quinin e b y oxidatio n o

f impur e aniline . Instead , h

e discovere da

n anilin e dyestuf

f wit h abrilliant

purpl e colo r

whic h h e name d mauveine . Thi s discover

y prompte dPerki n to abando n hi s research a t Roya l Colleg e an dto enter

commercia

l productio n a

l Green ford . I n th e early 1860s , commercia l exploitatio n o

f Perkin' s proces s brough t

a n acute shortag e of

benzene . I

t was recognize dtha t

mor e benzene wa

s presen t i n coa l ga s than i

n coa l tar . Dr . Car o o

f th e Badische Co . i

n German y develope da proces s fo r benzene recover

y fro mcoa l ga s b y oi l scrubbin g an dwas grante da paten t thereo n i n 1869 . Thi s proces s enable dbenzene productio n t o expan dt o mee t deman da s ne

w chemica

l use s fo r i t wer e developed . Durin g thi s inauguratio n o f commerc e i

n benzene recovere dfro

mcoa l tar , th e recover

y o f "carboli c acid " a s aby-produc t o f benzene vaf

s begun . J . Fairli e ha ddiscovere dcreso l i

n coa l ta r creosote a

t Universit y Colleg e (London ) i

n 185 5 [7] . However , th e first commercia

l us e o f "ta r acid " di dho t

aris e unti l afte

r the I86 9 discover

y o f it s antisepti c propertie s b y Josep h L . lister , a

n Englis h surgeon . A s aresult o f th e efforts o

f Mansfield , Perkin , Lister , Hofmann , an dman yP.7 3



### 21 6 Cresol s an d Cresyli c Acid s Cresol s a n

others , ther e wa s b y 187 5 asignifican t industr y establishe daroun drecover y o f chemical s fro mcoa l tar . However , th e requirement s fo r coke , particularl y i

n England , wer e s o grea t

tha t th e need s fo

r coa l la r were adequatel y serve db y incrementa l recover y ofcoa l tar . Th e firs t tru e by-produc t

cok e ovens , designe d especiall y t o facilitat e recover y o f cok e by-products , wer e constructe dby Albert Hussne r a t Gelsenkirchen , Germany , in 1881 . Thes e oven s supplie dth e risin g Germa n chemica l industr y whic h wa s largel y based o n coal-ta r derivatives . It wa s no t unti l 189 3 tha t

an y by-produc t

oven s wer e erecte din th e Unite dState s whe n abatter y o f

1 2 oven s wa s designe d:\nd buil t h y Loui s Seme l fo

r th e Solva y Proces s Co. , Syracuse , Ne w York , largel y t o obtai n ammoni afo r us e i n th e ammonia-sod aprocess . B y 1900 th e valu e o f th e volatil e product s ha dbee n establishe dan dth e combine deconomic s an dqualit y o f by-produc t

cok e becam e entrenche da s preferre dfue l fo r blas t furnace s b y th e growin g stee l industr y in th e Unite dStates . Fro m188 0 unti l 189 9 th e use s o f antisepti c pheno l wer e adequatel y supplie d fro mcoa l tar , eve n thoug h i t ha dbee n know n for

som e tim e tha t

pheno l coul d

TABL E 2 Histor

y o f Cokin g i n the Unite dStates *

Yea r . 188 0 189 3 189 5 190 0 190 5 191 0 191 5 192 0 192 5 193 0 193 5 193 7 193 9 194 1 194 3 194 5 194 6 194 8 195 0 195 5 I96 0 196 5 197 0 197 3 Oven s i

n E By-produc t 0 1 2 7 2 1,08 5 3.15 9 4.07 8 6.26 8 10,88 1 11,29 0 12,83 1 12,86 0 12,19 4 13.01 0 13.01 6 14,25 3 14,51 0 14,49 4 15,13 9 14,98 2 16,03 9 15,32 3 14.35 7

—
— ustenc e

Behiv e 12.37 2 44.00 0 45,49 3 57,39 9 84,40 5 100,36 2 93,11 0 75,29 8 57,58 7 23,90 7 13,67 4 12.19 4 10,93 4 18,69 9 17,66 6 12,17 9 12,86 4 14,07 8 17,70 8 10,10 4 7,58 3 3,43 3

—
— Cok e Produce d( M tons ) By-produc t 0 1 3 1 9 1,07 6 3,46 2 7,13 9 14.07 3 30,83 4 39,91 2 45,19 6 34,22 4 49,21 1 42.88 2 58,04 8 63,743 62,09 4 53,92 9 68,30 0 66,90 0 73,60 0 56,21 9 65,19 7 65,65 4 63,49 6 Behiv e

3.30 0 9.46 5 13.31 5 19,45 8 26,76 9 34,57 0 27.50 8 20,51 1 11,35 5 2,77 6 91 7 3.16 5 1.44 4 6.70 4 7,93 3 5,21 4 4,56 8 6,60 0 5,80 0 5,20 0 1,00 9 1,65 6 87 1 82 9 Tota l 3.30 0 9,47 8 13,33 4 20,53 1 30,23 1 41,70 9 41.58 1 51,34 5 51,26 7 47,97 2 35,14 1 53.37 6 44.32 6 64,75 2 71,67 6 67,30 8 58,49 8 74,90 0 72,70 0 78,80 0 57,22 8 66,85 4 66,52 5 64,32 5 Blas t

Furnac e Rat e (l b cok e pe r to n pi g iron- f ferr o alloys )

—
—
—
— 2,17 0

— 2,12 0

— — — 1.93 0

. . „ —
—
— — 1,93 7 1,86 5 $ 1 6 l;-33 0 1.^ 7 I.2J2 2 'Fro mMinerals Yearbook, U.S . Burea u o f Mines .P.7 4

d s Cresol s an d Cresyli c Acid s 21 7

o f i n b y e d cr t n g

. I t te s :h e : i n .•c n ^k e ee l ie d ul d TABL E 3 Histor y o f Productio n an dRefinin g o f Coke-Ove n Ta r

an dProductio n o f Ligh t Oil"

Yea r I9I 0 I9I 4 I9I 8 192 3 192 9 193 3 193 7 194 I 194 3 194 5 195 0 195 6 196 5 197 3 Ta rProduce d

( M gal ) 66.30 3 109.90 1 263,29 9 440.90 7 680.86 4 363.29 9 603,05 3 704.14 9 738,16 7 696.30 7 739.86 8 832.80 0 802.73 7 732,45 5 Coa l T
.

M Gallon s

— — — 328.08 7 215,55 0 378.93 5 458,33 4 532,68 3 562,44 6 607,248 702.09 1 678,30 7 562,14 3 i rReline d

Percen t o f Productio n

— — — 48. 1 59. 3 62. 9 65. 1 72. 2 80. 8 82. 1 84. 3 84. 5 76. 7 Ligh t Oi l Produce d

( M g.il )

— 87.22 0 101.43 8 164,48 8 96.63 2 187.10 3 234.02 6 264,32 1 260.23 7 260.85 8 290.90 0 262.70 0 214,20 1 "Fro mMinerals Yearbook, U.S . Burea u o f Mines . b e synthesize dfro mbenzen e b y sulfonatio n an dfusion . Despit e th e discover y b y Turpi n i n 188 5 o f

th e explosiv e natureofpicricacid.i t wa s no t unti l th e Boe r Wa r create dalarg e deman dfo r explosive s tha t

i t becam e practica l t o mak e pheno l synthetically . I n 1899 , Rea dHollida y & Co . initiate dcommercia l productio n vi abenzen e sulfonation/fusion , th e sam e yea r a s th e discover y i n German y o f

th e analgesi c propertie s o f apheno l derivative , acctyl-salicyli c acid , whos e discover y prove damajo r impetu s t o sustainin g th e commercia l futur e o f syntheti c phenol . I n 190 6 alarg e batter y o f by-produc t

oven s designe db y Heinric h Kopper s wa s installe da t

Joliet , Illinois , fo r

th e Illinoi s Stee l Co . Durin g th e followin g year s th e developmen t

o f by-produc t

cokin g evolve dsteadil y unti l i t receive da n enormou s boos t

i n 1914-1918 , spurre do n b y majo r expansio n o f

th e stee l industr y an db y surge s i n deman dfo r toluen e an dothe r

coa l chemical s durin g Worl dWa r

I . I n 191 4 th e H . Kopper s organizatio n wa s acquire db y th e Mello n interest s an dunde r

aggressiv e ne w managemen t secure dadominan t

positio n i n by-produc t

cokin g wit h respec t

t o numbe r

an dsiz e o f

installations . Th e evolutio n o f

coa l carbonizatio n i n th e Unite dState s ca n b e see n i n th e statistic s o f

cokin g (Tabl e 2 ) an dth e productio n an drefinin g o f cok e ove n ta r (Tabl e 3) . £ I n 1909 , Le o H . Baekelan dsuccessfull y develope dImpractical , thermoset

tin g plasti c resi n base do n condensatio n o f phenol-formaldehyd e [5] . Th e earl y product s o f

Genera l Bakelit e Corp. , whic h Baekelan dorganize di n 1910 , foun d succes s i n molde dparts , insulatin g varnishes , an dlaminate dsheet s fo r th e growin g electri c an dautomaliv c industries .P.7 5

21 8 Cresol s an d Cresyli c Acid s Cresol s an t



### Th e emergin g phenoli c plastic s busines s increase ddemand s fo r th e recover

y o f phenol s an dcresyli c acidfro mcoa l tar . Fro mthe earl

y 1920s thi s us e o

f ta r acid s comprise dtheir

majo r market , andi

t ha s remaine dasubstantial end-us e o f cresyli c acid s to the presen t time . B y th e en do f Worl dWa

r I I th e number

o f cok e oven s i n existenc e i

n th e Unite dState s wa

s i n exces s o f 27,000 , 14,49

4 o f whic h wer e by-produc t

ovens . O f thes e by-produc t

ovens , 11,06

9 wer e o f Kopper s o

r Koppers-Becke

r design . Aggregat e coa l tar productio n ha

dreache dalmos t

800,000,000 gal/yr , o

f whic h 80.8 % wa s being refined , an dthe aggregate productio n o f cresol s an dcresyli c aci dwa s approximatel y 5 0 M

M lb/yr i n additio n to approximatel y 2 0 M M lb/yr o f natura l phenol . I n th e early 1940s , Dr . H . L . Lochte , aprofessor a t th e Universit

y o f Texas , isolate dan didentifiedman y constituent s i

n th e cracke dnaphth aproduce di n petroleu mrefinin

g [10] . I n 1946 , Joh n T . Files , astuden t o f Lochte's , was convince dtha

t cresyli c aci dcoul dbe recovere deconomically fro mth e spen

t causti c generate di

n th e treatmen t

o f cracke dnaphtha . B

y 195 1 h e wa s instrumental i

n constructin g an doperatin g aHousto n plant (Meriche mCo. ) base don th e spent

causti c acquire dfro

mGul f Coas t refineries . B

y 1956 , other s ha dfollowe dsuit : Producto l Co . i

n Sant aF e Springs , California ; Pitt-Conso l Co . i n Newark , Ne

w Jersey ; an dNorthwes t PetrochemCo . i

n Anacortcs , Washington . I

n 195 6 thes e companie s wer e producin g atota l of

3 5 M M lb/yr o f cresyli c aci dfro

mpetroleu msources' . Coa l tar cresyli c aci dproductio n i

n 195 6 was abou t 9 0 M M lb/yr . Durin g th e perio dfro

m195 6 to 1974 , technolog y improvement s i n cok e elliciency b

y blas t furnace s resulte di

n diminishin g cok

e productio n i

n the Unite dStates . Durin g th e sam e time , avas t

increas e i

n catalytic-crackin g capacit y was made b

y th e petroleu mrefining industr y i n respons e to increase d deman di n quantity an dqualit

y o f moto r fuels . Thes e change s cause dashif t i n th e source s o

f cresyli c acids . B

y 1974 , petroleu mha

ddisplace dcoa

l ta r as th e dominan t sourc e o f cresyli c acid . Also , durin g thi s sam

e period , commercia

l productio n o

f certai n isomer s b

y synthesi s was begun , largely i n respons e t o specifi

c requirements .
Processe s 

### I n all processe s fo

r producin g phenol s th e personne l safet y an denvironmental hazard s associate dwit

h phenol s mus t

be take n int o accoun t

i n operatin g an d design practices . Essentia

l informatio n fo

r saf e handlin g o

f pheno l an dcresol s i s give n i n appropriat e chemica

l Safet y Dat aSheet s SD-4 an dSD-48, publishe d b y th e Manufacturin g Chemist s Associatio n [13] . A n immediat

e personne l hazardassociate dwit

h th e handlin g o

f thes e material s stem s from r 

### the fac t that painfu l burn s ca n result fro miheir contac t wit h ski n o r mucou s membranes . Th e hazard s associate dwit h handlin g solution s o

f th e sodiumsalt s o

f cresol s andcresyli c aci dar

e substantiall y equivalent

to thos e fo

r handlin g causti c sod a solutions .P.7 6

Cresol s an d Cresyli c Acid s 21 9

Coa l Ta rAcid s 

### Th e manufacture o

f cok e i n by-produc t

cok e oven s typically result s i n th e productio n o

f 10 to 1 6 ga

l o f ta r an dligh t oi l pe r to n o f coal . Th e crud e coa

l ta r is subjecte dto distillatio n t o yieldligh

t oi l (5%) , middl e oi

l (17%) , heav

y oi l o r creosote oi

l (17%) , an dpitch (61%) . The cresyli c aci dtypically represent s abou t 2 to 3 % o f the origina

l ta r an dis primaril y presen

t i n the ligh t oi l (u p t o 200°C ) andth e middl e oi l (20 0 to 250°C ) fractions . Th e classica

l proces s fo

r recoverin g cresyli c aci dfro mthes e tar distillate s stem s al

l th e wa y bac k to Charle s Mansfield' s pioneerin g wor k i n 1848 . Th e appropriat e ta

r fraction containin g ta

r acid s i s washedwit

h acausti c sod asolution , resultin g i

n th e formatio n o

f their sodiumsalt s whic

h are called sodium cresylates. Afte

r th e sodiu mhydroxid e ha s becom e 7 0 to 75 % utilized , the cresylate i s withdraw n fro mth e washer . Neutral oil s an dpyridin e base s whic h ar e presen t i n thi s cresylate solutio n are removedb y stea mdistillatio n under vacuu mwher e thes e impuritie s ar c removedwit h th e aqueou s con densate . The phenol s are recovere db y "springing' * the strippe dcresylat e wit h C0 2 

### - ric h gas . as fro

malim e kiln , an dremovin g the liberate dcresyli c aci db y decantation . The resultin g sodiumcarbonat e solutio n is the n causticize dwit

h lim e to regenerate causti c sod asolutio n fo r the washers . I n washin g th e middl e oi

l fraction o

f ta r distillate whic

h i s typically ric

h i n naphthalene , i

t i s normall y necessar

y t o operat e the washe

r a t elevate d temperatur e (~75°C ) to avoi dnaphthalen e crysta l deposit s i

n th e washer . Th e crud e cresyli c acidfro mth e decanter

afte r springin g i s normally dehydrate db

y distillatio n an dfractionate dinto variou s isomer s or mixture s o

f isomers . Th e cresyli c aci drecovere dfro mcoa l ta r typically contain s 45 % phenol . 35 % cresols . 15", , xylenols . an d5 % othe r phenoli c homologs . Refiner y Spen t Causti c 

### I n man y refineries , thermal an dcatalyti c cracke ddistillate s are causti c sweetenedto remov e mcrcaptans; coincident component s o

f th e spen t causti c ar e phenoli c material s whic

h are containe di

n th e for mo f sodiumcresylates . A typica l spent causti c contain s 15 % hydroxide . 20", , cresyli c acids . 10", , sulfu r compounds , an dth e balanc e wate r an dothe r

impurities . Th e cresyli c aci dca

n b e removedfro

mth e spen

t causti c b y neutralizatio n wit h acid . Sulfu

r impuritie s ma

y b e remove dbefor

e neutralizatio n b

y oxidatio n to disulfid e oil s and/o r

afte r neutralizatio n b

y extraction . The extractio n rout e utilize s mor

e comple x equipment

an dinvolve s solven

t recover y b y distillation . Th e neutralizatio n ca

n b e achieve db

y aci dgase s suc

h a s C0 2 

### , S0 2 

### or

H 2 

### S , or b y minera l acids . By-product s o

f C0 2 

### , S0 2 

### , an dH 2 

### S neutralizatio n ar e sodiumcarbonate , sodiu msulfite , an dsodiu msulfide . Afte r neutralizatio n an d remova l o f oil . water , an dsulfur , the aci dca n b e fractionate dinto' avariet y o f phenoli c homolo g fractions . j Th e approximat e isome

r distributio n i

n natural cresyli c acid s fro m pciroleumsource s i s pheno l 20% , ..-creso l 18% , /;;,/;-creso l 30% , xylenol s 22",, .

# T P.7 7

22 0 Cresol s an d Cresyli c Acid s Cresol s a >


### an dC 3 

### an d highe

r alky l phenol s 6% , wit

h th e balanc e being trimethy l phenol s an dethy l phenols . A residu e strea mequa l to abou t 3 % o f th e tota l fractionate d phenolic s listedabov e i s als o produce dwhic h ma y b e use di n creosote treatmen t o f lumbe r or fo r fuel . Th e processin g o

f refiner y spent causti c solution s fo

r recover y o f cresyli c aci drequire s asubstantiall y integrated , rathe r comple x plant facility . Th e larges t an d mos t integrate doperatio n o

f thi s typ e i

n th e worl di s foun

di n th e Meriche mCo . plan t

i n Houston , Texas . Th e basi c processe s use di n thi s operatio n include man

y ecologica

l innovations , includin g fou l air incineratio n an da n extensiv e wate

r management

system , necessitate db

y th e natur e o

f th e spen t causti c ra w material . Thes e are shown on th e bloc k proces s flo

w shee t i n Fig . 1 . Spen t caustic , collecte dfro

mman y refinerie s an d admixe dwit h recycle water , i s first

sweetenedi

n reactor s i

n whic h air i s disperse dinto th e alkalin e liquid . Th e exi

t air , befouledwit

h trace s o f noxiou s component s an ddenude do f oxygen , i s incinerate d prio r

t o releas e l o Ih

e atmosphere . The spen

t causti c is then extracte dwit

h a n immiscible solven

t fo r remova l o f sulfu r compounds .
PHENO L - CRESOL S • XYLENOL S - CRESYLI C ACID S - FRACTIONA L DISTILLATIO N

SULFU R
__ _ COMPOUND S "*- ] 

# £ SOLVEN T REGENERATIO N

SWEETENIN G REACTOR S SOLVEN T EXTRACTIO N

WATE R MANAGEMEN T SYSTE M ' lll l REOCL E ' ' ' ' r WATE R W4IE R IMPOUNDMEN T (R_I N RUNOFF : QUI P SYSTEM !

COOLIN G TOWER S
PROCES S SIEA M B0ILE P 0R&W00W N IPfAlMfN I STEA M f\ AN 1

SODIU M SULFID E CONCENTRAT E 

# n CRUD E DISTILLATIO N

NEUTRALIZATIO N

PHENOLS EXTRACTIO N 

# U SOLVEN T REGENERATIO N

MULTIPL E EFFEC T EVAPORATIO N 

# €

FIG . 1 . Cresyli c aci d recovery fro m refiner y spen tcaustic .P.7 8



### d s Cresol s an d Cresyli c Acid s 22 1 ol s te d .n t •li e 

### "h e th e hi s o n the

. i n cle in e lo f : is ds . Th e purifiedspent causti c i s "sprung " or

neutralize dwit

h asuitabl e acid , normall y hydrogen sulfide , i n areacto r

syste man dseparate dinto th e primar y phase s of crud e cresyli c aci dan daqueou s sodiu msulfide . Th e sodiu msulfid e liquor , afte

r extractio n fo

r remova l o f phenols , i s fe

dt o amultipl e effec

t evaporato r

an dsubsequentl y withdraw n fo r marketin g a s asodium sulfide/hydrosulfide concentrate . Condensat e wate r fro mth e evaporator s i s diverte dinto awate

r management

syste mfo r balance dreus e an ddispositio n as describe delsewher

e [12] . Tight

wate r management

an dextensiv e wate

r reus e are practice di

n cresyli c acidrecover

y operation s to insur

e tha t no phenol s escap e to surfac e wate

r estuaries . Afte r the primar

y phas e separatio n fro

mneutralization , the crud e cresyli c aci dis subjecte dto distillatio n to remov e th e tarlike residue . Finally , th e cresyli c acidenter s afractionatio n trai n wher e i t i s separate dint o it s constituent s and/o r trad e mixtures . Significan t Produc t Fraction s o f Natura l Cresyli c Acid s Th e fraction s o

f recovere dphenoli c isomer s whic h ar c significan

t commercially are 99 + % Pheno l 99 + % o-Creso l 9 6 + %/;7,/7-Creso l 8 5 + %/;;,/>-Crcso l 

### Mixe dxylenol s Mixe dxylenol s an dethy l phenol s Alky l phenol s (C 3 

### an dC 4 

### ) Variou s blende dcresyli c aci dmixture s Th e recoveredpheno l compete s directly wit h syntheti c phenol , is asmall portio n o f th e total pheno l market , an di s competitively price dwit h syntheti c phenol . Othe r

cresyli c isomer s als o have price s influence db y th e marke t

pric e o f phenol , benzene , an dtoluene . Certai n isomer s i n hig h purit y hav e value s of

tw o t o thre e time s pheno l marke t valu e du e to complexit

y o f synthesi s and/o r

th e complexit y o f separation s processe s t o recove r themfro mnatura l cresyli c aci d streams .
Use s 

# f \ Som e majo r use s of o-cresol are a s a

n intermediate i

n herbicides , i

n dye carriers , an di n th e formulatio n o

f additive s fo

r lubricants . Thre e herbicide s prepare dfro mo-creso l ar e 2-methyl-4-chlorophenox y22 2 Cresol s an d Cresyli c Acid s 

### aceti c aci d(MCPA) , 2-methyl-4-chlorophenox y proprionat e (MCPP) , an d2.4

- dinitro-o-creso l (DNOC) . Thes e ar e widel y use di n Europ e an dtheir

us e i n th e Unite dState s i s continuin g to grow . Th e majo r use s o f mixe dm,/;-cresol s ar

e i n the manufacture o

f phosphat e ester s an dindustrial phenoli c resin s an da s solvents . Hig h purit y p-creso l i s use

d a s a n intermediate i

n th e manufacture o

f th e antioxidan t

2,6-diterbutyl-/>

- cresol . Xylenol s an dcresyli c acidmixture s ar e use di n phosphat e este

r functiona l fluids

- industrial phenoli c resins , an dwir e enamel solvents , i

n additio n t

o man y minor uses . A n approximat e profile o

f use s fo r cresol s an dcresyli c acidi n th e Unite d State s i s Phosphat e ester s Wir e ename l solvent s Antioxidant

s an dadditive s Resin s an dadhesive s Miscellaneous 2 5 1 7 1 6 1 7 2 5
Syntheti c Cresol s 

### Syntheti c route s to creso l manufacture hav e th e advantag e ove r recover y processe s i

n allowin g manufacture o

f hig h purit y isomer s wit

h les s by-produc t o f lo w deman disomer s tha

n i s containe di

n natura l creso l sources . However , th e ra w materia l cos t i s muc h highe r sinc e th e buildin g block s are pheno l or toluen e whic

h have hig h marke t value s relativ e to finished creso l prices . Ther e are fou r processe s use

di n th e commercia

l synthesi s o

f cresols : (1 ) alkylatio n o

f pheno l wit

h methanol , (2

) toluen e sulfonation , (3 ) cymen e cleavag e to creso l an dacetone , an d(4)chlorinatio n o f toluene . Thes e ar

c discussedi

n bricfbclow . Alkylatio n 

### Alkylatio n o

f pheno l wit

h methano l i s acommercially importan t sourc e o f syntheti c o-creso l an d2,6-xyleno L Th e major

commercia

l us e o f 2,6-xyleno l is a s ara w materia l fo r polyphcnylencoxid c polymer s develope db y Genera l Electri c Co . Reactio n betwee n pheno l an dmethano l ove r catalys t favors formatio n o

f ortho-substitute dcresol s an dxylenol s wittipesse r activit y a t th e par asit e an dver y littl e attac k

o n th e met asite . CatalysPsclcctio n i s critica l i n controllin g th e relativ e proportio n o f alkylatio n betwee

n o r 

### rtho an dpar asites , wit h mor e acidi c catalyst s leadin g to increase dpara-site Activity . Methanatio n a

t th e metasite range s fro mvirtually ni

l to amino r contaminatio n dependin g o n reactio n conditions . Th e meta-sit e methanatio nP.8 0

Cresol s an d Cresyli c Acid s 22 3

whic h doe s occu r

i s presumabl y forme dby isomerizatio n o f othe r isomer s rathe r tha n activit y o f

th e met asit e durin g alkylation . Reactio n temperatur e ca n hav e agrea t effec t o n selectivit y o f

th e alkylatio n fo r orth o substitution . Lo w temperature s (belo w 200° ) resul t in productio n o f anisol e a s th e majo r

product . Othe r

sid e reaction s for

msmal l amount s o f dimethy l ethe r

an ddipheno l oxide . Alkylatio n may tak e plac e i n aliqui do r

vapo r reaction , bu t

catalys t cos t an dunfavorabl e increase s i n productio n o f

ni, /.-cresol a s asid e produc t hav e reduce dth e commercia l valu e o f th e liquid-phas e process . Subsequen t

t o th e alkylatio n reaction , remova l o f sid e product s (water , anisole , dimethy l ether , mixe dxylenols , in, p-cresol, trimethy l phenols , unre acte dphenols , an dmethanol ) i s required . Pur e o-creso l ca n b e recovere d throug h fractionation , bu t 2,6-xyleno l wil l contai n m, p-cresol unles s a n extractiv e ste p follow s distillation . Productio n o f

pur e isomer s by thi s rout e i s economi c du e t o ashortag e o f petroleu man dcoa l ta r

productio n o f

thes e isomers , bu t

ra w materia l cost s mak e th e produc t

mor e expensiv e t o produc e tha n materia l recovere dfro mby

produc t streams . Vapo r phas e reactio n ove r

alumin acatalys t

i s use dt o produc e roughl y 10 0 M M lb/y r

o-creso l an d2.6-xyleno l i n th e Unite dStates . Worldwid e productio n o f a n additiona l 5 0 M M lb/y r i s reported . Sulfonatio n
y ; t Creso l manufactur e by sulfonatio n o f toluen e i s a n analogou s proces s t o pheno l manufactur e b y benzen e sulfonation . excep t tha t th e reactio n rat e i s greater . Th e reactio n take s plac e in fou r steps , a s follows : > r e )f j l v . Sulfonatio n I . C ft H s CH , + H : S 0 4 - - C h H 4 (CH.,)(SO,OH ) + H : 0 Neutralizatio n

j f i s a l r s i e i n :s . o r 31 1 2 . 2C„H 4 (CH.,)(SO,OH ) + Na 2 SO ;i - > 2C„H 4 (CH.,)(S0 2 ONa ) + SO , + HX ) + Na 2 S0 4 Causti c fusio n 3 . C h H 4 (CH 3 )(S0 2 ONa ) + 2NaO H - C f ,H 5 (CH 3 )ON a+ Na 2 S0 3 + H, 0 Acidificatio n 

# i
4 . C ( ,H 3 (CH 3 )0H a+ SO , + H 2 0 + H,S0 4 - } C„H 5 (CH.,)O H + Na,S0 3 + Na 2 S0 4P.8 1

22 4 Cresol s an d Cresyli c Acid s Creso l



### 1 . Toluen e sulfoni c aci di s formedb y reactio n o

f toluen e i n th e vapo r

phas e wit h concentrate dsulfuri c acid . Wate r i s removedazeotropicall y durin g reaction . 2 . Sodiumtoluenesulfonate i s formedb y neutralizin g wit

h sodiumsulfite . S0 2 

### i s boiledoil'an d sodiumsulfat e is filtere doui . 3 . Sodiu mcresylate is formedb y fusio n o f the sulfonat

e wit h sodium hydroxide . 4 . Fre e creso l i s formedb y acidifying the cresylat

e wit h SO' . Creso l i

s removedb

y phas e separatio n an ddecanting . Th e produc t i s then distille d fo r remova l o f cresyli c impurities . Th e produc t

o f sulfonizatio n is generally abov e 80%/;-creso l wit h in- an doisomcr s forming the bul

k o f th e impurities . Som

e pheno l an dxylenol ar

e present . Th e isome

r distributio n is altere db

y temperatur e an

dacidstrengt

h i n sulfonation . Cymen e Cleavag e 

### Cymene cleavag e processe s ar e use dcommercially t

o produc e m,/;-cresol s wit

h relativ e quantitie s o

f approximatel y 60 % metaan d40 % para . o-Creso l is nearly absent du e to difficult

y o f conversio n o

f o-cymen e to cresol . Thi s make s the cymene proces s fo

r in. p-cresol attractiv e to en duse s i n whic h o-cresol is a

n undesirabl e impurity . Th e cymen

e proces s fo

r syntheti c m.p-cresol s begin s wit h productio n o

f cymene fro

mtoluen e an dpropylen e ove r aFriedel-Craft s catalys t (e.g. , aluminu mchloride) ; in- an dp-cymen e are prevalent . Toluen e an dpolyisopro

py l toluen e are remove db

y distillatio n afte

r neutralization . Cymen

e is then ai

r oxidize dto hydroperoxycymen e ove r anobl e catalys t

(palladium) . Unreacte d cymene i s removedb

y distillatio n leaving aconcentrate dhydroperoxycymen e whic h i s cleave dinto aceton e an dcreso l i n a n acid-catalyze dreaction . Finally , acetone , unreacte dcymene , cresols , an dby-product s are separate db y distil

lation . Th e yiel

do f toluen e eventuall y converte dt o in, p-cresol range s fro

m8 0 to 95% . Thi s proces s i s utilize dt o produc e syntheti c m,p-creso l i n Japan . Toluen e Chlorinatio n 

### Followin g th e sam

e mechanis ma s fo

r th e manufacture o

f pheno l b

y th e chlorobenzen e route , cresol s have bee n manufacture di

n Europ e b

y chlori

natio n o f toluen e followe

db y hydrolysi s wit

h sodiumhydroxid e a

t elevate d temperatur e an dpressure . Th e resultan t sodiumcresylat

e i s acidifiedto yiel

d mixedcresol s an dsodiu mchloride . vTh e mixe dcresol s forme

dcontai n approximatel y 60^ , w-crcso l wit h th e balanc e being o- an dp-cresol . I n orde r t o be eeonomical,-th e proces s require s salt electrolysi s to regenerate th e chlorin e an dcausti c consumed . Th e yiel do f thi s proces s is approximatel y 70 % conversio n o f toluen e l o cresol .P.8 2

id s

as e in g ilc . u m I i s le d

. 1 » - ar e 1 in Cresol s an d Cresyli c Acid s 22 5

*- *

•it h irl y th e a n o r .g. . •ro ai r te d en e 

### ny . ail

-

. 8 0

th e ori

- .te d iel d th e ire s : t o TABL E 4 U.S . Marketer s andProductio n Capacit y (captiv e productio n no t in

cluded ) Producer Capacit y (M M lb/yr) Coa l tar : Kopper s U.S . Stee l
Petroleum : Meriche mCo . Producto l Division , Northwes t

Petroch e Ferr o Corp .

mica l Division . Stimso n Lumbe r

Co . Alabam aWester n Synthetic : Conoc o Chemical s Kopper s Sherwin-William s 3 0 2 0 5 0 10 0 3 0 3 0 1 0 17 0 5 0 1 0 4 0 10 0 Process :

Alkylatio n Alkylatio n Sulfonatio n

Productio n
Se e Tabl e 4 . 

### Bibliograph y Patent s U.S . 2.042.33 1 (1936) . T . S . Carswcll (t o Monsant o Chcmiea

l Co.) . U.S . 2,225,56

4 (1940) . J . W . LcMaistr

e e t al . (l o Theo . Swann) . U.S . 2,362,61 2 (1944) , W . B . Brow n (t o Allie dChemica

l andDye) . U.S . 2,438,12 5 (1948) , E . J . Loran det al . (to Hercule s Powder) . Britis h 600,83 7 (1948) , N . M . Cullinan e andW . C . Davi s (t o Pete r Spenc e & Sons) . U.S . 2,551,62 8 (1951) , J . E . Nickel s (to Kopper s Co.) . U.S . 2,632,77 4 (1953) , J . C . Conner e t al . (t o Hercule s Powder) . Germa n 889,44 3 (1953) , E . Bruening ct al . (to Bayer) . U.S . 2,728,79 7 (1955) , L . J . Fila r (t o Hercule s Powder) . U.S . 2,751,41 8 (1956) , H . J . Eno s (t o Hercule s Powder) . British 754,87 2 (1956) . Hercule s Powder . U.S . 2,744.14 3 (1956) , L . J . Fila r (t o Hercule s Powder) . U.S . 2.767,220 (1956) , M . B . Neuwort h (t o Pitt-Consol) .