University ofHyogo
Universityof Hyogo161)

CrowilEthers.2.
CationBindingPropeniesofBenzo-type
EffectofLarge Ring Sizeupon ComplexationPhenomena ofCrown-7 and Crown-8Derivatives2)
Mikio OUCHI, Masaya KOJIMA, YUkinori OTOSHI, Hiromitsu YOSHIDA.

andHiroshi SHIBA[IrA

Department ofMaterials

Scienceand Chemistry

GraduateSchoolofEngineering
Abstract
and benzo-24-crown-8has beenperfbrmedby
The cation-binding by two large
ring-sized
benze-21-crown-7
the solvent extraction of monovalent
metal pierates
KJ',(Na', Rb'.Cs',Ag',and Tl")betweenEarater anddichlolomethane.
The effeet of ringsize and benzo group upon the cation bindng ability isdiscussed,[[he21-crown-7
resultsare comparedwith benzo-18-crown-6and simple unsubstituted ero"m ethers (18-crozam-6,ab-ty
as theand 24-crown-8). Itwas found that largeringbenzo-crowll
ethers havelower cation binding
withsimple
unsubstituted
crown ethers while cation selectivity forlarge
catiens
ringsize increasescomparedTl')hasbeenobsenied.
and(Cs'Key Words: orown

ethers,extraction, supramolecularsolventchemistry

1. Introd"ction
functionalized
crown ether compounds
have been synthesized to control thecomplexation
Pedersen's
phenomena with catiens. The original papar bypieneeringwork in 1967 l3]stillgivesthe ideaof
abilities
systems. XM3 have recently reported the cation-binding
theappToach fbrthedesignof supramolecularderivatrves
weresupenor
toless-symmetricalbenzo-"Jpecro"methers
and
found
that
dibenzo-crown-6of
in viewof cation bindmg and cation selectivity
Itwas also furthersuggested themonobenzo-crown-ethers
ring toward heai7 metal bindingespecially forsilver and thallium
role of benzene(I)[1].
A widevarietyofether mainlythat the cation-binding
ability, and the cation selectivity of a crownIthas beenbelieved
depend upon the fbllowing
factors;1)relationship betweenthecavity size ofthe erown ether and the cation
flexibility
or rigidityof a crownetheg and 4)
diameteg2) number of donor atoms, 3) confbrmational
ether [4].
[[hesynthetic approach forthemolecular designof crown ethers has
lipophilicityof the crownof introduoing
the substituents,
startedfrom mono- or dibenzo-typecrownethers becauseof the feasibility
This study hasbeen done in many papers, however, the structuTes of benzo-typecro"M ethers are maiiily
benzo-crown-4,5, allddibenzotypecrown ethers or mono-benzo type crown ethers withsmall mhg size (e.g.
investigate
thecationbinding abmaties ef
6 derivatives).
In thiscontext, itis our special interest
tolarge cro"m ethers, benzo-21-crown-7 (1)and benzo-24-crown-8(2).
Theirsyntheses are
mono-benzo
of aqueeus
metaland
theircation
binding
abitities
havebeen
evaluatedbysolventextraction
described,

The results werepierates.
and commerciallyavailable"rith those of 21-crown-7

compared

24-crown-8(4),benzo-18-croswn-6(13),(3),18-crown-6(14).

ExperimentalDetails'
infraredspectra were obtained

2.

JASCO A-1OO gratingspectrophotometer.
Mass spectra were measuredin
NMR spectra were recorded on a JEOL JNM-EX 27e spectrometerusing ShimazuGCMS-QP5000.
standard. UV-VIS spectra were recorded on
chlorpform-dsolution containing
1% tetramethylsilaneas intermal
Melting pointswere measured svith a MEL-[[IEMPapparatus and are
a HitachiU-3500 spectrophotometer,from sodium hydride.Commer ¢ iallyavailable
Solventtetrahydrofill'an(THF)was distillod
uncorrected.
onaiH

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Universityof Hyogoof bewi mi inwe lhhatiTes17
iIN/detion
Z.enectof buge
RdgSinmpi thmplczEcim
enenomenaofBm-,tipe
dmv]Btutu
Bindmginpenits
X"･,we･xa･SH

reageats wereailsed

unless noted othenN'ise.
inthe followingsyntheses withoutfrirther
purificatien"" ×.

,(I 5ohoo.

S9OOH
OHwoo"

s-4il-2

Oo5Oo5ooc )ag:)
yoVyoV

Hoc(xroff)iilroHTso6of)i}xroTs

o9[n=210:n=3
11:n=4-12/n=58:m=5nO

N1.

3Il=1

IIk=1
2:k=2

6:m=3-7im==4.

(oO(C../ovQohL3oL4in.1,Z-Bis{(2-hydroxyethyi)oxylbenzene
Synthesis(5)was synthesized from eatechol and 2-chloTeethanol
76-78℃
methedto the similar reported[S].mpin 3796 yield according
ethanol in the presenceof NaOH
iH
293S,6,9g
IR
4.10-4,143,91-3.92℃ [5]), NMRS 3.24-3.29(m.4H),(t4H), (s,4H).CKBr)(t2H),(lit.78-802810, 1510,1450, 1260,ll20,1040, 740 cm-i.
and excess amountof ethylene
Pentaethyleneglycol(7)was synthesized from triethyleneglycoldichleride
172℃ 10,6Torrglycolin the presenseof KOH in4S% yield aceording to the pTevious reported method [6].bpiHNMR℃ fO.6Tbrr [6]),(lit175

IR(neat)33Se, 285e, 1460, 1350, 1240.
3,56-3.78(m,20H).
6 3.42(s,2H),

1100 cm'i.
of diethylene
and exccss amountglycel dichloride
Hesaethylene g]ycol(8)was synthesized fromdiethylene
190℃ 19i.3[[b",thereportedrnethodbpin40%according
to[7]
yield
glycolin the presenceof sodium metaliH
1260,1110
cm.
1460, 1360. 1300,IR (neat)
3360, 2860
3.62(s.24H).
NMR 6 2.95for.s.2H).
,,16SO,

fromthe corresponding oligoethylene glycol
Oligoethy]eRe(9,IG,11,12)g[ycotditosy[atesto the reported
accordingchloride in THF inthe presenceof NaOH in 83-89% yield
andp-toluenesuifOuyliH
TheNMR. and IR spectra were inagreement with the publisheddata
from the authors7 group [g].
methodweresynthesized[8],Benzo-21-Cre"rn-7
intoa 2-L threewere introdueedO.35mol)and THF (400mL)
KOH (19,8g,(1).

neckedinlettube,To theO.Imol)
added bis[(2-hydroxyethyi)oxy]benzene(5)(19,gg, in THF (400mL),(le)glycolditosylate
forI h withconsecutive bubblingof nitrogen. Tetaraethylene
and stirring was continued
stirring
was
mixtureover2h,andthedropwise
tothestirredO,lmol)inTHF(200mL)was then added(SO.2g,wasevaporatedandtheresidue[[hesolvent w'asa nitrogen atmosphere.
centinued for 2 days at 66 ℃ under
wassulfate and the solvent
The chloroform extract was driedover magttesium
extracted with chlorDfbrm.

fiaskequippedwith a magnetic
stirred suspension
at 66 ℃ wasstirrer, reflux

condenser,

anddroppingfunnel.

nitrogen

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REPORTSUNIVIIRSrrY OF HYOGOOF GRADUA[PE SCHooL OF ENGMEERI]NIG,

No,se(2005)

ohloroform-hexane2:1)tolt-was purifriedby column chromatography(alumineg]H
3.91-3.94
NMR63.6S
3.80-3.g2
15.9g
of
the1(astheoily(t,4H),(s.SH).
give(45%)
productpreduct):
4.1S-4.18 (t.4H).
6.90(s,4H);
MS rnle 379 (M'+Na).
(t.4H).
O.05mol) and hexaethyleneglycolditosylate
The alternativemethed
was from cathecol (29.5g,(12)(6.lg,iHTheNMRKOHO.19rnel)
for24hours
in13%
O.055mol) inTHF inthe presenceof(10.8g,(2.3g)
yield,
wasidenticat
withthe aboye data.
spectmnifrom 5 (2.5g,O,O13mol) and pentaethy}eneglycolditosylate
Benzo-24-Crown-8 (2)was synthesized(11)
O.O10mol) in THF in the presenceof KOH (5,lg,O,09mol)in 36% (1.Sg)yieldas the oily product(5.5g,iHNrm
6 3.64-3.81(t.20H),
3.g9-3.92(t.4H),
4.14-4,20(t.4H),
above,
aeeerding to the proceduredescribedMSrnle424Na').
6.90(s.4H);(M"+O.llmol) and triethylene glycol
21-Crowll-7 (3)was synthesized from tetraethylene glycol (6)(21.7g.
O.IOmol) in THF in the presence of KOH (19.6g.
O,35mol) in 29% (9,eg)
ditosylate(9)(45.8g,yield,above. Itwas purified
by distillation
under reduced
according to the similar proceduredescribedpressure. bpiH
3.69 (s.28H);
IR (neat)2860, 1460,1350, 1300,12SO,111O cm-i; MS 308 (MD,153℃ /O.85[Ibrr; NMR ti'6O.1Omol)
aiid 10 (47.7g,O.095mol)in THF in the presenceof
24-Crown-8 (4)was synthesized frorn (I9.4g,bpO.25mol) in 7% (2.4g)
KOH (16,5g,yieldaccording to the proceduredescribedabove (21-Crown-7).
'H
2850, 1450,1350, 1300,175℃ fO.8Ibrr; NMR 6 3.63(s.32H);
IR (neat)
1250,1120cm'i;MS 352 avf'),
O,O02Smol)and 9 (1.15g,O,O025mol)in THF in theBenze-18-Crovvn-6(13)was syithesized from5 (O.50g,mentionedabove. mp 40 ℃
O,027mol)
in36%
accordingtotheyieldprocedure
presenceof KOH (l,54g,iH4,14-4,20(t.4H),
6.90(s.4H).
℃ [3]); NMR 6 3.70-3.80(t.12H),
3.90-3.95(t,4H),(lit.43are similar to those
SolventExtraction.The generalextractien procedures employed
previously
presented[9],water were used, The solvents were saturated with each other
Dis'tilled
dichloromethaneand demineralized
beforeuse in order to preventvolume changes of the phase duringextraction. Equal volumes (10mL) ofcrownether
diohloromethanesolution of the respective(3.0mM)and of an aqueous solution ef theThe
metalmM)
were shaken fbr10 minutes at 25 ℃ ina Taiyo MlOOL incubator,
corresponding
picrate (3.090 minutes
at thattemperature in order to complete
mixturewasthen al]owed to stand forat leastphase
by fi1tration
separation. The organic phase was separated(Tbyofilter
paperNo.2s). Sincethepicratesdo notand
in dichloromethane.
the molar extinction coecacierrts in Iil mixture Qf dichloromethane
dissolve
wasofalkaliand
heavy
metalintheorganicacetonitrile
were determined.
The eoncentration
phase
pierateandacetonitrile.
from absorbanceat 375 nrn ina mixture ef dichleromethane
determined

evaporated,Afterwork-up,

3. ResultsandDiscussien
ethers has been presentedinPcdersen's
Synthesis.The generalideaof the synthesis of mono-benzo-crown
thereaction
ofcatechol
andoligoethylene
The produet is obtained by(orwork
glycol dichloridest3],ditosylates)in the presenceof NaOH (orKOH). Howeveg gligoethylene
glycolspossessing more than 6available. Theyshould beoxygenatoms (e.g.
penta-,hexa-,and heptaeth}rlene glycols)are not commerciallyunderhigh reduced pressure.
Itneeds sometimes earefhl attention andsynthesized
and purified
by distillation
andditosylates
forthefbrstudents. Then they are converted to theirdichlorides
techniques of theirpteparation
21,and
in
the
crewn
ether
ring
benzo-18,ethers with6-Soxygen
atorns(e,g.
synthesis of mono-benzo-crown
24 crown ether derivatives)using catechol as starting material,and2-chloroethanol
inethanol incatecholwas converted
te 5 by reaction ofcatechol
In the presentstudy,
in 37% yield,
The compound5 hastwo side chains possessingoxyethylene chains thatthepresenceofNaOH
ether
ring. 5 isalso obtainedby arystallization and itiseasy to handle
ef the crownwould be the compongnt

it'
1 was synthesized
ethers,Thus 5 isthestarting material ofthe synthesis oflaige ringmono-benzo-erownfrom 5in45%
Benzo-24-Crowm-8wass}mthesized
from5 and 10 in THF in thepresenceofKOHyield,(2)
theyieldsof thein 36% yield,No attempt was made to maximize
and 11 in THF inthe presenceof KOHof1and2products, howevegtheyields
Benzo-18-Crown-6(13)was also synthesized according to the same method while itcan be synthesized
13 was synthesized from 5 and 9 inTHF in the presenceef KOH infrom catechol and 11 below30 % yield.

36V6 yield.
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oflkpm bovncaera
Z,Mfutof lage
Ring
Sbempo campte
auianPtmeza
diimveTutCrwv]-8
Derivatives19
Bindiing
PNperties
Jfi･,wa,re･:M,MM:fafoElargeririg-sized
crown
Unsubstituted(3)was syllthesized from 6 and 9 in THF in the presenceef KOH in
in7% yield.The oily
29% yield. Likewise,4 was synthesized from 6 and 10 in THF inthepresenceofKOH
reducod
3and
4werebydistillation
underpressure.
purdiedpreducts
Though the generalideaof the above synthetic methods has boen alreacly reported by other and ourin detail,The present
thecharacteristie infbrmationsof the compounds havenot beendescribedgroupsi5,6],synthesizing
large
iing-sized
macrocyclie
strategic idea
and drrection
incase ofresults would give thc detailedcompounds.

techniques forevaluating the characters of macrocyclie
SolventExtraction.A wide variety of measurement
have been reported. For cTown ethers, solvent extraction techniques are quite popular andcompounds
methodto evaluate cation bindingability. In the presentstudM aqueous some alkali and heavy
convenientsolution of theK", Rb', Cs',Ag', and Tl')were extracted at 2S℃ withdichlorometharre
metal picrates(Na',in 1fable1,In the present studM data
crowii ethers (1,2,3,4,13,and 14).[[heextraetabilities obtained are shown
arefordiscussion,obtainedby thissolvent extraction of metal picrates presented ge'neral

Table 1.SolventExtraction
efMetalLigandNa'"

K'Picratesa)9'6Extraetabilityb)

Rb'Cs'Ag'

Tl-F

9,O22.222,419.9lg23L3
52.841.963.648.455.073.2
19.713,724.916243,O69,O
33.118.543.122.428.657.6
36.418.452.232,417.036,712341314 1.7112325.12.963a) Ibmperature25 ℃ ;aqueous phase

OrganicPhase (CH2C12,(1Oml):[picrate]=3mM.

10ml):[Ligand]=3mM.

b)Definedas percentpicrateextraeted intothe organic phase.Ayerageof two independentruns.

andcrown-8
crown-7
As seen from Table 1, largering-sized(1,2,3,4)
possesshigh extractability fbrCs'
itwas found that la[gering-sizedand Tl' while
13 and 14 possesshighextractability forK' and Tl',Generally
cationseiectivib,
fbrlaigeringsizeincreases,
andethers
have
lewer
cationbindingabilityasthebenzo-crown
acceptedsize-fit
This would be clearly explained by the generallyandTl')has been observed.
cations (Cs'e,crownethers
irrespective
ef the ring size [10].
and unusual high Tl' binding ability for mostconecpt [3]ringsize,the cation bindingcrown
ethers"dththesame
Compared with benzo-crownethers and unsubstituted
crown ethers; e.g. thelower thanthe corresponding unsubstituted
ability of benzo-crown ethers are generally
dataof 1 vs. 3 and those of2 vs. 4. The exceptions are Na" and Ag' for2.
atem
atom of the crown ether ring.Basicityof oxyge]
of oxygen
Tlieresults are explained by the basicity
abilityof thenext to the benzene ringof1 and 2 islower than that of3 and 4 which causes the low binding
Thisand14).
alreadyshewn
fbr
crown-6
derivatives(13,crownethers formest cations. This has been
tspecomplex betwcen
explanation wouldbe based on the 1i! crown ether-cation complex and no sandwich
for
Benzo-24-Crown-S
highNa'andAg'
extractability(2)might be fromcrown ether and cation. The unusualcomplexforsmallsize catsonsof 1:2 crewn
ether-cation
thechange of complex fbrmationas thepossibility
tethe fUrtherex'tractson experiments
crewn
ethers. To get the elear-cut evidence,
toward largcring-sizedThis
investigation
isinshouldbeneeded.
pregress, 1
deterrnine
theextraction equilibrium constants (K..)
show
the newwhich
w'ouldbe conyerted
to themulti-reop typebenzo-crewn ethers [11]and 2 would
characterofcrownethers,

References
H, Ueda, M. Kejima, and[I]Part Ii M, Ouchi, T. Kinashi,
S7,36 (2004).
Engineering,(iniversityof,Efyogo,R. Miyoshi,Reports ofGraduate Slthool
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REPORrs OF' GRADUATESCHOOL OF ENGINEERING, UNIVERSrrY OF HYOGO No.58 (2co5)

and M. Ouchi,[21Preliminaryresults,ofthe work ime beenpresented: H. Ybshida,M, Kojima,H. Hiroshi,ofJapan, RA5O, Ube,2005.
Society
Abstraets
ofthe West-JapanRegionalMeeting ofthe Chemical[3]C.J.Pedersen,J.Am. C7,em.Sbc.,S9, 7017 (1967).
andReactivityof theconcept, see: Ede Jong and D.N. Reinhoubt,stabih'ty
descriptionof[4]For a detailed
Crdwn Elrher
Comptexes.
Acadernic,London, I9g2.
ftah'ana,
117,717 (1987).
[S]B.R Czeeh,A. Czech,B.E.Knudsen. and R,A. Bartsch,GuaettaC7?imica
J, Org, Chem.. 49, 1408 (19S4).
[6]M. Ouchi,Y/ Inoue.T. Kanzaki,and T,Hakushi,
Christensen,
Thompson,E.D.
Flanders,R.L.CarTuth,
R.M, Izatt,and J.J.
J.S,
Bradshaw,RA.
ReedeqM.D,[7]J Org. Chem.,41, 134 (1976).
S.Nakamura, K. Whda, and T. Hakushi,Butl.Chem.Sbc..ipn,,[g]M, Ouchi,YZ inoue,Y Liu,S.Nagarnune,
63, 1260 (l990).
T.Hakushi,
and E.Webeg J Org.Chem., 52, 2490 (1987).
[9]M. Ouchi.YZ Inoue,K, Whda, S. Iketani.
Hakushi,
CooTzienem.Rev,,
148,
171
M.
Chichi,andT.
(1996).
[IO]
benzo-erown-ethers)
have been presented:
M.
Preliminaryresults of the work (especiallyon double-loop[11]H, Sakamoto,and K. Kimura, Abstracts
efthe 54thAnnual Meeting ofthe
Ouchi,T. Ybkohara,R. )vfiyoshi,
forAnalytical
ChemistrM
Nagoya,2005.
Japan Society
p268,

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