ISSN 1070-4272. Russian Journal of Applied Chemistry, 2006, Vol. 79, No. 3, pp. 425! 429. + Pleiades Publishing, Inc., 2006.
Original Russian Text + A.N. Belyaev, A.V. Vershinin, K.V. Gromov, L.L. Kuznetsov, 2006, published in Zhurnal Prikladnoi Khimii, 2006, Vol. 79, No. 3,
pp. 432! 436.
AND INDUSTRIAL ORGANIC CHEMISTRY
Separation of 2,4<- and 4,4<-Dihydroxydiphenyl Sulfones
A. N. Belyaev, A. V. Vershinin, K. V. Gromov, and L. L. Kuznetsov
St. Petersburg State University of Movie and Television, St. Petersburg, Russia
Received April 27, 2005; in final form January 2006
Abstract-To develop a procedure for separating 2,4`- and 4,4`-dihydroxydiphenyl sulfones, their acidity and
solubility in water were studied.
Bisphenol S prepared by the reaction of 2 mol of
phenol with 1 mol of sulfuric acid is a mixture of
4,4`-(I) and 2,4`-dihydroxydiphenyl sulfone (II) with
small amounts of 2,4`,4"-trihydroxytriphenyl disulfone
(III) and unidentified colored and colorless impurities.
Previously crude bisphenol S was used for prepar-
ing macromolecular components of heat-developable
mixtures and photoconductors. At present, only pure
sulfones I and II are used for this purpose. Sulfone III
does not find practical application so far. Most of the
procedures for separating sulfones I and II are based
on their different solubilities in organic solvents. Since
only isomer I was used in practice, these methods
consisted in its separation from concomitant impuri-
ties. Isolation of individual sulfones I and II by
treatment of bisphenol S with a boiling mixture of
p-xylene and isopropanol or methyl ethyl ketone was
described in patent .
Procedures involving no organic solvents are more
convenient for industrial applications. Components of
bisphenol S were separated in the form of their mono-
sodium salts  by the following procedure. An iso-
mer mixture was dissolved in approximately 2 equiv
of aqueous alkali to form the disodium salts readily
soluble in water. Only the monosodium salt of I was
precipitated after partial neutralization of the solution.
As stated in patent , under these conditions isomer
II is in the solution in the form of its disodium salt.
The suspension was filtered. Monosodium salt of
isomer II was crystallized after partial neutralization
of the filtrate. The salt was separated from the solu-
tion. Acidification of an aqueous suspension of this
salt gave pure sulfone II. Monosodium salts of sul-
fones I and II were recovered in 97 and 83% yields
respectively, from a mixture containing 79 wt % sul-
fone I, 20 wt % sulfone II, and 1 wt % impurities .
The purity of both isolated salts was no less than
90%. Thus, this method seems promising for develop
a high-performance industrial process for separating
isomers I and II without using organic solvents.
We experimentally tested the procedure described
in patent . The results of separation of bisphenol S
are presented in Table 1. Isomer I was isolated in a
yield of 93 wt %, which is close to the yield reported
in the patent. However, instead of pure isomer II we
obtained only a mixture containing 48 wt % target
To exclude the possible influence of impurities
which can be different in bisphenol used in  and in
our sample, we prepared a model mixture containing
pure isomers I and II in the ratio equal to that in the
bisphenol described in patent  (Table 1, run no. 2).
The results of separation of this mixture also differed
from those reported in the patent.
Since, according to patent , monosodium salt of
isomer I is formed and crystallizes in a solution in
which isomer II is in the form the disodium salt, the
acidity of sulfone II should be substantially higher
Table 1. Results of separation of a mixture of dihydroxy-
diphenyl sulfone isomers
³Component content, wt %
³ ³ ÃÄÄÄÄÄÄÂÄÄÄÄÄÂÄÄÄÄÄ
³ I ³ II ³ III
1 ³Bisphenol S ³ 50 ³ 82.0 ³ 16.5 ³ 1.5
³Isomer I ³ 40.5 ³ 93.2 ³ 6.6 ³ 0.2
³Isomer II ³ 7.9 ³ 45.6 ³ 48.0 ³ 6.4
2 ³Model mixture ³ 50 ³ 80.0 ³ 20.0 ³ 0.0
³Isomer I ³ 42.8 ³ 88.3 ³ 11.7 ³ 0.0
³Isomer II ³ 6.9 ³ 61.9 ³ 38.1 ³ 0.0