4
28
BELYAEV et al.
sodium salt of II is lower than that of monosodium
salt of I in the whole temperature range. These data
clarify the experimental results on separation of mix-
tures of isomers I and II.
washed with distilled water, and dried at 110 120 C.
The yield of crude bisphenol S containing 82, 16.5,
and 1.5 wt % of sulfones I, II, and III, respectively,
was 143 g (90%).
Since separation of sulfone I from impurities of
isomer II was performed by treatment of their ammo-
nium salts [11], we studied the solubility of monoam-
monium salt of I in water at different temperatures.
The solubility of this salt in water is noticeably lower
than that of the monosodium salt, with the difference
being the most pronounced at low temperatures. The
Individual isomers I and II were obtained by
separation of crude bisphenol using a benzene acetone
mixture by the procedure described in [7]. The melt-
ing points of isomer II and I recrystallized from
5
% aqueous ethanol were 185 186 and 248 249 C,
respectively, which is close to the published data
(
186.7 and 249.5 C, respectively [7]).
solubility c (wt %) of the sodium salt at 10, 30, 40,
Monosodium salts of sulfones I and II and
s
5
0, 60, 70, and 80 C is 6.0, 7.0, 8.2, 11.1, 14.6, 16.6,
monoammonium salt of I were prepared by dissolu-
tion of these sulfones in 1 equiv of aqueous solution
of the appropriate base on heating. The precipitates of
these salts formed on cooling were filtered off and
dried at 105 110 C. As determined by UV spectros-
copy, the content of the target product was no less
than 99.5%.
and 20.1, respectively; the solubility of the ammoni-
um salt at 20, 30, 40, 50, 60, and 70 C is 3.4, 3.6,
4
.8, 7.1, 11.0, and 15.0, respectively. Thus, isomer I
can be purified more efficiently in the form of mono-
ammonium salt as compared to its sodium analog.
Thus, separation of isomers I and II in the form of
their monosodium salts based on the difference both
in their acidities and in solubilities in water at a usual
content of isomer II in the mixture (15 20 wt %) is
ineffective. However, if the content of isomers I and
II in the mixture substantially differs ( 85 and
Chromatographic analysis of crude bisphenol S and
the isomer mixtures was performed on a Milikhrom
chromatograph using columns packed with Sil 600.
A mixture of hexane (40 ml), ethyl acetate (20 ml),
acetic acid (2 ml), and trifluoroacetic acid (0.5 ml)
was used as the eluent. The wavelength used for
2
wt %, respectively), the salts of these compounds
detection was
= 260 mn.
can be separated by the procedure described in [11].
This procedure is unsuitable for isolation of pure II.
The content of individual isomers in aqueous solu-
tions was determined by their absorption measured in
1
-cm quartz cells on an SF-26 spectrophotometer. The
EXPERIMENTAL
molar extinction coefficient of isomers I ( = 295 nm)
and II ( = 275 nm) measured in solution with
pH 11.0 11.5 was 27400 and 15450 l mol cm ,
respectively.
Crude bisphenol S was prepared by sulfonation
of phenol in the presence of o-dichlorobenzene.
A 250-ml three-necked flask equipped with a ther-
mometer, a mechanical stirrer with a seal, and a Wurtz
adapter with a descending condenser was loaded with
phenol (120 g) and dichlorobenzene (80 ml). To this
solution, 92% sulfuric acid (68 g) was added with stir-
ring at 100 110 C within 10 min. The mixture was
kept at 100 110 C for 1 h and then was heated to
boil at 140 145 C. The aqueous azeotrope of o-di-
chlorobenzene was separated and the organic layer
was returned to the reaction mixture. The temperature
of the reaction mixture increased to 180 C within 5 h.
Then the reaction mixture was cooled, and o-dichloro-
benzene was decanted. A solution of sodium hydrox-
ide (51 g) in water (150 ml) was added to the residue.
The resulting suspension was heated at 90 95 C with
stirring until a solution was formed. The residual
organic solvent was separated, and the solution was
diluted to 600 ml with distilled water and acidified
with 70% sulfuric acid to pH 3. After cooling of the
reaction mixture, the precipitate was filtered off,
1
1
Crude bisphenol S was separated by the procedure
in [2]. Crude bisphenol S (50 g) was placed in a
250 ml three-necked flask equipped with a thermom-
eter, a mechanical stirrer, and a reflux condenser.
A solution of NaOH (17 g) in water (75 ml) was added.
The resulting suspension was refluxed until a solution
was formed. 72% sulfuric acid (12.6 g) was added. The
suspension was slowly cooled to 40 C. A precipitate
of monosodium salt of isomer I was filtered off and
the liquid phase was thoroughly removed by pressing.
The filtrate was heated to 90 95 C with stirring and
acidified to pH 3 4. After cooling, the precipitate of
isomer II was filtered off, washed with distilled water,
and dried at 105 110 C. Isolated monosodium salt of
isomer I was suspended in distilled water (120 ml).
The suspension was heated to 90 95 C with stirring
and acidified to pH 4 5. After cooling, the precipitate
of isomer I was filtered off, washed with distilled
water, and dried at 105 110 C.
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 79 No. 3 2006