Method and catalyst for making bisphenol

A sulfonated aromatic organic polymer, such as sulfonated polystyrene ion-exchange resin is provided having ionically bound N-alkylaminoorganomercaptan groups. The ion-exchange resin can be used to effect phenol-ketone condensation.

CROSS REFEREMCE TO RELATED APPLICATIONS 
Reference is made to copending application of Gary R. Faler and R. George 
Loucks Ser. No. 342,435, filed Jan. 25, 1982, now U.S. Pat. No. 4,424,283, 
for Catalyst for Synthesizing Bisphenol and Method for Making Same. 
BACKGROUND OF THE INVENTION 
Prior to the present invention, various methods were employed to synthesize 
bisphenols, such as bisphenol-A, by effecting reaction between a ketone 
and a phenol. One procedure, for example, involved the use of large 
amounts of inorganic acid catalysts, such as sulfuric acid or hydrochloric 
acid. Experience has shown, however, that the use of inorganic acids 
requires a means to neutralize such acids at the end of the reaction due 
to the corrosive action of the strong acids. In addition, distillation of 
the resulting bisphenol is often required because of the many by-products 
formed during the reaction under high acid conditions. 
An improved procedure was developed to synthesize bisphenols by using a 
solid resin cation-exchange catalyst to effect phenol-ketone condensation. 
A disadvantage of the ion-exchange catalyst, however, is its relatively 
low acid concentration resulting in slow reaction rates. Rate acceleration 
has been achieved through the use of mercaptans. Apel et al. U.S. Pat. No. 
3,153,001, shows incorporation of mercaptan by partial esterification of 
the ion-exchange catalyst in the form of a sulfonated insoluble 
polystyrene resin. Another procedure (McNutt et al, U.S. Pat. No. 
3,394,089) shows the partial neutralization of aromatic sulfonic acid with 
alkylmercaptoamine. A further procedure is shown by Wagner et al. U.S. 
Pat. No. 3,172,916, based on the partial reduction of the sulfonic acid to 
afford thiophenol functional groups. 
Further improvements in synthesizing bisphenols from ion-exchange resins 
are shown by Faler et al. U.S. Pat. Nos. 4,294,995, 4,346,247, and 
4,396,728, assigned to the same assignee as the present invention and 
incorporated herein by reference. Faler et al. utilize certain 
N-organoaminodisulfide to incorporate covalently bonded organomercaptan 
groups into the backbone of sulfonated aromatic organic polymer. 
Although particular improvements have been obtained by using ion-exchange 
resins of the prior art, it has been found that available ion-exchange 
resins comprising sulfonated aromatic organic polymer having chemically 
combined aminoorganomercaptan groups do not provide a satisfactory degree 
of activity, selectivity and stability with respect to catalyzing the 
conversion of a ketone to a bisphenol as a result of reaction with a 
phenol. 
As utilized hereinafter, the expression "catalyst activity", or "% 
conversion" (% C) means 
##EQU1## 
Catalyst activity is calculated under continuous steady-state reaction 
conditions from data obtained at a temperature of 60.degree. C. to 
85.degree. C. In measuring catalyst activity, ion-exchange resin is used 
having an attachment level of about 4 to 40 mole percent of 
aminoorganomercaptan sites, at a Weight--Hour--Space--Velocity (WHSV) 
averaging about 3.0 to 16.0 parts of feed, per part of ion-exchange resin, 
per hour. 
The expression "selectivity", or "S", is specific to the production of 
bisphenol-A and is calculated as follows: 
##EQU2## 
The selectivity value is also calculated from data obtained under 
continuous steady state and WHSV conditions as defined above. 
The term "stability" with respect to defining the characteristics of 
ion-exchange resins having chemically combined aminoorganomercaptan groups 
means the ability to resist change in % conversion and selectivity under 
continuous steady-state operating conditions as previously defined. In 
calculating ion-exchange resin stability, an initial average "base" value 
for % conversion and selectivity is determined over a period of up to 4 
days under continuous steady-state conditions. A subsequent average 
"trial" value for % conversion and selectivity is thereafter computed by 
continuous use of the ion-exchange resin for a period of up to 60 days. 
Catalyst stability is expressed as follows as a % conversion variance "% 
CV" over the trial period: 
##EQU3## 
The present invention is based on the discovery that substantial 
improvements in conversion of acetone to bisphenol, and higher yields of 
p-p-bisphenol-A can be obtained by using effective amounts of sulfonated 
aromatic organic polymer having from about 4 to 40 mole percent of 
ionically bound aminoorganomercaptan groups of the formula, 
##STR1## 
where R is a C.sub.(3-10) divalent organo radical, and R.sup.1 is a 
C.sub.(3-8) monovalent alkyl radical. 
For example, it was found that sulfonated cross-linked polystyrene resin 
having about 24 mole percent of ionically bound 
n-propylaminopropylmercaptan groups within the scope of formula (1) 
provided a 69% conversion of acetone and had a selectivity of 45.8 during 
an initial 4 days continuous run which fell to only a 68.8% conversion and 
a selectivity of 44.8 after 25 to 28 days of continuous operation. This 
was found to be substantially superior to sulfonated cross-linked 
polystyrene resin having about 21 mole percent of ionically bound 
aminoethylmercaptan groups which showed under the same continuous reaction 
conditions for making bisphenol-A, a 57.0% conversion and a selectivity of 
only 27 which was substantially maintained over a 25-28 day period. On the 
other hand, a sulfonated cross-linked polystyrene resin having about 18 
mole percent of covalently bound propylaminopropylmercaptan groups, had a 
% conversion of 71.9 and a selectivity of 35.2 after the four day base 
period which fell to a % conversion of less than 40 and a selectivity of 
less than 24 after a 25-28 day trial run. 
STATEMENT OF THE INVENTION 
There is provided by the present invention an ion-exchange resin comprising 
sulfonated aromatic organic polymer having ionically bound 
N-alkylaminoorganomercaptan groups of formula (1). 
There is also provided by the present invention a method for making 
bisphenol which comprises reacting a ketone and a phenol in the presence 
of an effective amount of a cation-exchange resin comprising a sulfonated 
aromatic organic polymer having from about 4 to 40 mole percent and 
preferably 25 to 35 mole percent of chemically combined sulfonated 
aromatic organic units with ionically bound N-alkylaminoorganomercapto 
radicals of formula (1). 
There are included by the C.sub.(3-10) diorgano radicals of R of formula 
(1) alkylene radicals for example, trimethylene, tetramethylene, 
pentamethylene, hexamethylene, etc.; aromatic radicals, for example, 
phenylene, xylylene, tolylene, naphthylene, etc. R also includes 
substituted alkylene and arylene radicals as previously defined, for 
example, halo substituted for example, chloro, bromo, fluoro, etc. There 
are included by R.sup.1 radicals of formula (1) monovalent alkyl radicals 
such as propyl, butyl, pentyl, hexyl, heptyl, and octyl. 
The sulfonated aromatic organic polymer which can be used in the practice 
of the present invention to make ion-exchange catalyst having ionically 
bound alkylaminoorganomercaptan groups of formula (1) include, for 
example, Amberlite-118, manufactured by the Rohm and Haas Company, Dowex 
50WX4, manufactured by Dow Chemical Company and other sulfonated aromatic 
organic polymers such as sulfonated polystyrenes which have been 
crosslinked with divinylbenzene. 
Phenols which can be used in the practice of the present invention to make 
bisphenol include, for example, phenol and substituted phenols, such as 
##STR2## 
where R.sup.2 is a monovalent C.sub.(1-8) alkyl radical, for example, 
methyl, ethyl, propyl, etc., and a is equal to 0 or 1. 
Ketones which can be employed in the practice of the present invention to 
make bisphenols are, for example, acetone, diethylketone, 
methylethylketone, cyclohexanone, acetophenone, etc. 
The ion-exchange resins of the present invention can be prepared by 
effecting reaction between sulfonated aromatic organic polymer and 
N-alkylaminoorganomercaptan monomer which can be in the form of the 
hydrohalide or corresponding hydrotosylate. A convenient synthesis of the 
N-alkylaminoorganomercaptan hydrotosylate, for example, can involve an 
initial reaction between a bromochloroalkane and an alkali metal 
thiosulfate which can be refluxed in an inert atmosphere in an organic 
solvent such as aqueous methanol. There can be added to the resulting 
reaction mixture an appropriate alkyl amine which can be further refluxed. 
Methanol and excess alkyl amine can be distilled from the mixture and 
isopropanol added to remove the water by azeotropic distillation. The 
alkylaminoorganothiosulfate and by-product alkali metal halide can then be 
isolated free of water by filtration of the isopropanol slurry. 
A mixture of the above alkylaminoorganothiosulfate and paratoluenesulfonic 
acid monohydrate with methanol can be refluxed under nitrogen, followed by 
a standard organic extraction and work up which provides the desired 
product in a chlorinated hydrocarbon solvent. The tosylate salt can then 
be precipitated by addition of an appropriate aliphatic hydrocarbon 
solvent and isolated by filtration. 
The ion-exchange resin catalyst of the present invention having ionically 
bound N-alkylaminoorganomercaptan groups can be made by effecting reaction 
between the sulfonated aromatic organic polymer and the 
N-alkylaminoorganomercaptan salt in the form of a halide salt or tosylate 
salt as described above. The sulfonated aromatic organic polymer in the 
form of a dry resin can be initially analyzed for sulfonic acid content by 
a standard neutralization technique and typically contains 22.1 millimoles 
of sulfonic acid groups per 4.70 grams of dry resin. An appropriate amount 
of the hydrohalide or hydrotosylate salt of the aminoorganomercaptan 
(typically 0.25 equivalents relative to sulfonic acid groups on the base 
resin) is heated as an aqueous solution in the presence of the base resin. 
The mixture can be heated at a temperature in the range of from 60.degree. 
C. to 70.degree. C. for 4 hours while being slowly agitated and thereafter 
allowed to cool to room temperature. The resulting ion-exchange catalyst 
can thereafter be filtered, washed with water, methanol and then vacuum 
oven dried. 
The percent nitrogen in the ion-exchange catalyst can be determined by the 
Kjeldahl method (Z. Anal. Chem. 22, (1883)). From this data, nitrogen 
milliequivalency/gram of dry catalyst can be determined which shows the 
fraction of total sulfonic acid sites occupied by 
N-alkylaminoorganomercaptan groups of formula (1). Mercaptan 
milliequivalency/per gram of dry catalyst can be determined using Ellman's 
reagent (A. Fontana and C. Toniolo, The Chemistry of the Thiol Group, S. 
Patai, Editor, John Wiley and Sons, Ltd., London (1979), pp. 288-290). 
With respect to the preparation of bisphenols utilizing sulfonated aromatic 
organic polymer containing N-alkylaminoorganomercaptan groups of the 
present invention, a mixture of phenol and ketone can be heated in the 
presence of the cation-exchange resin prepared in accordance with the 
practice of the present invention. There can be utilized 2-20 moles of the 
phenol per mole of the ketone which can be heated at a temperature in the 
range of from 50.degree. C. to 110.degree. C. with agitation. The 
ion-exchange resin can be employed at from 0.1% to 10% by weight, based on 
the weight of the total mixture in instances where a batch process is 
used. In a preferred procedure for making bisphenol in a continuous 
manner, the ion-exchange resin can be used in a column which can be 
operated at a temperature of 50.degree. C. to 100.degree. C. The mole 
ratio of reactants can vary widely, such as from about 3 to 1 to about 20 
to 1 moles of phenol per mol of ketone. It is preferred, however, to use 
the reactants at a mole ratio of about 4 to 1 to about 12 to 1 moles of 
phenol per mol of ketone. 
One method of recovering the bisphenol reaction product, for example, 
Bisphenol-A, is by crystallizing the BPA/phenol adduct from the reactor 
effluent and recovery of the bisphenol-A by distillation or 
crystallization. Other procedures are, for example, distillation of the 
reaction mixture to separate the phenol and bisphenol, or by partial 
distillation to remove the phenol followed by recrystallization of the 
residual bisphenol using water, methanol, acetonitrile, methylene chloride 
or toluene as the solvent. A crystallization procedure for BPA recovery is 
also shown by G. R. Faler, U.S. Pat. No. 4,375,567, assigned to the same 
assignee as the present invention and incorporated herein by reference.

In order that those skilled in the art will be better able to practice the 
invention, the following example is given by way of illustration and not 
by way of limitation. All parts are by weight. 
EXAMPLE 1 
A mixture of 50 grams of bromochloropropane, 78.8 grams of sodium 
thiosulfate pentahydrate, 250 ml of methanol and 50 ml of water was heated 
at reflux with stirring under a nitrogen atmosphere for 1.75 hours. The 
solution was allowed to cool to 35.degree. C. and 110 ml of n-propylamine 
was added to the mixture. The mixture was then refluxed for 16 hours. The 
mixture was then distilled until 190 ml of distillate was collected. There 
was added 1250 ml of isopropanol to the mixture and the distillation was 
continued. A total of 1170 ml distillate was collected. The mixture was 
allowed to cool to 60.degree. C. with stirring and 100 ml of n-heptane was 
added. The mixture was cooled to room temperature, filtered and washed 
with three portions of n-heptane and vacuum oven dried. Based on method of 
preparation, there was obtained 113 grams of a free flowing white powder 
in the form of N-propylaminopropanethiosulfate. 
A mixture of 113.05 grams of the above N-propylaminopropanethiosulfate, 
60.45 grams of paratoluenesulfonic acid monohydrate and 650 ml reagent 
grade methanol was heated at reflux with stirring under a nitrogen 
atmosphere. The mixture was refluxed for one hour and then cooled to room 
temperature. The resulting slightly cloudy yellow solution was then 
treated with 150 ml of water containing 20 grams of para-toluenesulfonic 
acid monohydrate and 400 ml of chloroform. The aqueous phase was recovered 
and washed with a 200 ml portion of chloroform followed by three 100 ml 
portions of chloroform. The organic layers were extracted with 150 ml 
water and then concentrated to 150 ml and allowed to cool to room 
temperature. There was then added 300 ml of n-heptane over a 10 minute 
period with stirring to provide a white yellow slurry. After stirring an 
additional 10 minutes, the slurry was filtered, washed with n-heptane 
several times and vacuum oven dried for three hours at 55.degree. C. to 
provided 43.4 grams of a free flowing white powder. Based on method of 
preparation, the product was 3-propylamino-1-propylmercaptan 
hydrotosylate. 
Five grams of Amberlite-118 was washed with 60 ml of water and 2.times.60 
ml of methanol. The resulting resin was then dried for 12 hours in a 
vacuum oven at 55.degree. C. to provide 4.7 grams of a sulfonated 
polystyrene having 22 millimoles of sulfonic acid groups. A mixture of 4.7 
grams of the resin, 24 ml of water and 1.680 grams of the above 
3-propylamino-1-propylmercaptan hydrotosylate was heated at 
60.degree.-70.degree. C. for 4 hours. The resin was then washed with water 
and methanol and air dried for several minutes and then dried in a vacuum 
oven at 50.degree. C. for 1 hour. There was obtained 5.6 grams of 
sulfonated polystyrene having about 24 mole percent of ionically bound 
3-propylamino-1-propylmercaptan groups based on nitrogen analysis and the 
use of Ellman's reagent to determine mercaptan attachment level. 
A feed mixture having an 8:1 mole ratio of phenol-acetone was pumped into a 
column containing the active catalyst at a WHSV of 4. The column was 
maintained at a temperature of 70.degree. C. The effluent was sampled 
daily and analyzed over a period of 28 days using HPLC to determine % 
conversion, selectivity and catalyst stability. 
In accordance with the above procedure, the same sulfonated polystyrene was 
used to prepare ion-exchange catalyst in accordance with the procedure of 
Faler U.S. Pat. No. 4,396,728 having about the same attachment level of 
covalently bonded 3-propylamino-1-propylmercaptan groups. Another 
ion-exchange resin was prepared having about the same attachment level, 
except that aminoethylmercaptan hydrochloride was substituted for the 
3-propylamino-1-propylmercaptan hydrotosylate. The % conversion, 
selectivity and stability of the catalysts were then determined over a 28 
day period under continuous operation as shown by the following results, 
where "Invention" means ion-exchange resin having ionically bound 
3-propylamino-1-propylmercaptan groups, "Covalent" means the resin 
prepared in accordance with Faler U.S. Pat. No. 4,396,728, "Ionic 
Aminoethylmercaptan" means the ion-exchange resin outside the scope of 
formula (1), % C means % conversion and % S means % selectivity: 
TABLE I 
______________________________________ 
Day 1-4 Days 25-28 
Catalyst % C S % C S 
______________________________________ 
Invention 69.0 45.8 68.8 44.4 
Covalent 71.9 35.2 &lt;40 &lt;24 
Ionic Amino- 57.0 27.0 56.2 26.0 
ethylmercaptan 
______________________________________ 
The above results show that the ion-exchange catalyst of the present 
invention having ionically bound 3-propylamino-1-propylmercaptan groups is 
superior as an ion-exchange catalyst with respect to % conversion, 
selectivity and stability when compared to prior art ion-exchange resins. 
EXAMPLE 2 
A mixture of 4.70 grams of Amberlite-118 containing 22.1 millimoles of 
sulfonic acid groups which had been washed with water and methanol and 
vacuum dried at 55.degree. C. for 12 hours was heated in 25 ml of water 
with 0.25 equivalents (relative to the sulfonic acid groups on the base 
resin) of the appropriate aminoalkylmercaptan hydrochloride or 
hydrotosylate salt. The mixture was heated at 60.degree.-70.degree. C. for 
4 hours while being slowly stirred and then allowed to cool to room 
temperature. The resulting ion-exchange catalyst in the form of a 
sulfonated polystyrene resin having ionically bound aminoalkylmercaptan 
groups was then recovered by filtering the mixture and washing the residue 
with three 60 ml portions of water, three 60 ml portions of methanol and 
vacuum oven drying the washed product at 50.degree. C. at 5 torr for about 
12 hours. The following table shows the catalyst prepared: 
TABLE II 
______________________________________ 
Ionically Bound Aminoalkylmercaptan Catalyst 
##STR3## 
Catalyst R.sup.3 
n x y 
______________________________________ 
1 H 2 0.21 0.79 
2 C.sub.3 H.sub.7 
3 0.24 0.76 
3 C.sub.3 H.sub.7 
2 0.24 0.76 
4 H 3 0.21 0.79 
5 C.sub.3 H.sub.7 
4 0.21 0.79 
6 H 4 0.21 0.75 
7 H 5 0.25 0.75 
8 H 6 0.23 0.77 
______________________________________ 
The ion-change catalysts shown in Table II were then evaluated for catalyst 
activity by pumping an 8:1 phenol:acetone mole ratio solution at a WHSV of 
4 through a column containing the catalyst at 70.degree. C. The effluent 
was sampled daily and analyzed by HPLC over 2 days. The following table 
shows catalyst effectiveness in terms of % conversion and selectivity: 
TABLE III 
______________________________________ 
Catalyst % Conversion 
Selectivity 
______________________________________ 
1 57 27 
2 69 46 
3 59 31 
4 72 48 
5 67 42 
6 72 53 
7 54 58 
8 67 55 
______________________________________ 
Evaluation of the ion-exchange catalysts shown in Table II was then 
continued following the same procedure illustrated in Table III by 
continuing the phenolacetone reaction for a period of up to 12 days to 
determine whether any change in catalyst stability was effected. The 
following results were obtained: 
TABLE IV 
______________________________________ 
1-2 Days 9-12 Days 
Catalyst % Conv. (Selectivity) 
% Conv. (Selectivity) 
______________________________________ 
1 57 (27) 56 (26) 
2 69 (46) 70 (43) 
3 59 (31) 56 (31) 
4 72 (48) 48 (46) 
5 67 (42) 61 (41) 
6 72 (53) 60 (47) 
7 54 (58) 32 (46) 
8 67 (55) 50 (47) 
______________________________________ 
The results shown in Tables III and IV establish that the ion-exchange 
catalyst having ionically bound alkylaminoalkylmercaptan groups within the 
scope of formula (1), as shown by catalysts 2 and 5, are superior to the 
other ion-exchange catalysts having ionically bound 
alkylaminoalkylmercaptan groups outside the scope of formula (1), if the 
total results shown for % conversion, selectivity and stability are 
considered together. Extended stability studies further established that 
catalysts 1 and 2 showed the smallest variance in stability over a 56 day 
period even though catalyst 2 within the scope of the invention exhibited 
superior % conversion and selectivity. It is not completely understood why 
a loss of stability was shown in catalysts 4 and 6-8, where n of Table II 
showed a value of at least 3 carbon atoms between the nitrogen atom and 
the sulfur atom. One possible explanation as shown by the performance of 
catalysts 2, 3 and 5 is that a side chain within the scope of formula (1) 
stabilizes the catalyst. 
EXAMPLE 3 
4-propylamino-1-butylmercaptan hydrochloride was prepared by the following 
procedure: 
There was added 1.8 ml of propylamine to a stirred solution of 1.985 grams 
of thiobutyrolactone in 10 ml of tetrahydrofuran. The addition took place 
over a 5 minute period at room temperature. The resulting solution was 
stirred at room temperature for 2 hours, followed by heating for 1 hour, 
cooling to room temperature and further stirring for 12 hours. Volatiles 
were removed from the mixture under reduced pressure to provide 3.12 grams 
of the desired mercaptoamide as a colorless oil. 
There was added 2.97 grams of iodine portion wise to a mixture which was 
stirring under nitrogen and cooled in an ice water bath consisting of 3.12 
grams of the above mercaptoamide and 15 ml of ethanol. The resulting red 
solution was stirred for 10 minutes and then 2.48 grams of sodium 
carbonate was added. There was then added to the mixture after 1 hour at 
0.degree. C., 2.5 grams of sodium bisulfite. There was then added 3 grams 
of sodium thiosulfate to the mixture. The mixture was partitioned between 
water and chloroform. The aqueous layer was washed with chloroform and the 
combined organic layers dried over anhydrous potassium carbonate, filtered 
and concentrated. There was obtained 2.71 grams of a white solid. Based on 
method of preparation, the white solid was the corresponding bisamide 
disulfide. 
There was added 959 milligrams of the above bisimide disulfide dissolved in 
15 ml tetrahydrofuran over a period of 1 minute to a mixture of 378 
milligrams of lithium aluminum hydride and 10 ml of tetrahydrofuran which 
was stirring under a nitrogen atmosphere. The mixture was stirred at room 
temperature for 45 minutes and then refluxed for 15 hours. Upon cooling to 
room temperature the reaction mixture was quenched by adding 0.4 ml water, 
0.4 ml 15% aqueous NaOH and 1.2 ml of water and stirred at room 
temperature for 3 hours. The mixture was filtered through Celite and the 
cake washed with 100 ml portions of chloroform and water. The aqueous 
layer was treated with sodium bicarbonate until slightly basic and 
extracted twice with 50 ml portions of chloroform. The combined chloroform 
solutions were concentrated to 15 ml and treated with gaseous HCl at 
0.degree. C. for 15 minutes. Upon concentrating the solution, there was 
obtained 609 mg of a white solid or a 47% yield. The white solid was 
4-propylamino-1-butylmercaptan hydrochloride based on NMR spectra and 
Ellman's analysis. 
Although the above examples are directed to only a few of the very many 
variables which can be used to make the sulfonated aromatic organic 
polymer ion-exchange resin of the present invention having 
N-alkylaminoorganomercaptan groups attached to backbone sulfonyl radicals 
by ionic ammonium-sulfonate linkages as well as the use of such 
ion-exchange resin as a catalyst for making bisphenols, it should be 
understood that a much broader variety of N-alkylaminoorganomercaptans as 
well as sulfonated aromatic organic polymer can be used to make such 
ion-exchange resin as well as phenols and ketones which can be used to 
make bisphenols as shown by the description preceding these examples.