Russian Chemical Bulletin, International Edition, Vol. 52, No. 8, pp. 1877—1878, August, 2003
1877
Reactions of chlorine dioxide with organic compounds
2
.* Oxidation of thiols
ꢀ
O. M. Lezina, S. A. Rubtsova, and A. V. Kuchin
Institute of Chemistry, Komi Research Center, Ural Branch of the Russian Academy of Sciences,
4
8 ul. Pervomaiskaya, 167610 Syktyvkar, Russian Federation.
Fax: +7 (821 2) 43 6677. Eꢀmail: info@chemi.komisc.ru
Oxidation of thiols with chlorine dioxide smoothly affords the corresponding disulfides.
Key words: chlorine dioxide, oxidation, thiol, disulfide.
Oxidation of thiols with various oxidants has been
on ChromatonꢀNꢀAWꢀDMCS as the stationary phase, helium
as a carrier gas). Organosulfur compounds were analyzed in a
temperature range from 50 to 250 °C at a heating rate of
6 deg min– . Compounds were identified by comparing their
retention times with those of authentic samples.
much investigated;2
—4
however, the use of chlorine diꢀ
oxide (ClO ) as an oxidant is only recent (see the relevant
2
1
5
,6
kinetic studies ).
We showed that oxidation of thiols 1a—c with chloꢀ
rine dioxide selectively affords disulfides 2a—c in high
yields.
Mass spectra were recorded on a Shimadzu QP 5050A
chromatomassꢀspectrometer (column SPBꢀ5 (60 m × 0.32 mm),
–1
column temperature 50—250 °C, heating rate 5 deg min ).
Melting points were determined in an open capillary.
Typical procedures for oxidation of thiols. A. Bis(2ꢀhydroxyꢀ
ethyl) disulfide (2c). A mixture of air and ClO (0.22 g, 3.2 mmol)
2
obtained from an aqueous solution was passed through a soꢀ
lution of ethanethiol 1c (0.5 g, 6.4 mmol) in AcOEt (5 mL)
for 2 h. Water vapors were collected in a trap with conc.
H SO . The reaction mixture was magnetically stirred for 2 h.
After the reaction was completed, the solvent was removed to
give disulfide 2c (0.47 g, 96%), m.p. 23—24 °С (cf. Ref. 8:
R = Bn (a), C H (b), C H OH (c)
6
13
2
4
2
4
Oxidation was carried out in three ways: a solution of a
thiol in an organic solvent was bubbled by passing an
air—oxidant mixture (method A); a thiol was added
dropwise to a solvent presaturated with the oxidant
2
4—25 °С).
B. Dibenzyl disulfide (2a). Benzylmercaptan 1a (0.5 g,
(
method B); and ClO dissolved in water was immediꢀ
4.0 mmol) was added dropwise at 20 °C to a solution of ClO2
2
ately mixed with a solution of the starting compound
obtained by bubbling AcOEt (5 mL) with a mixture of air with
ClO2 (0.136 g, 2.0 mmol). The reaction mixture was magnetiꢀ
9
(
method C).
cally stirred for 120 min. After the reaction was completed, the
solvent was removed to give dibenzyl disulfide 2a (0.96 g, 98%),
m.p. 70 °С (EtOH) (cf. Ref. 10: 70—71 °С).
In all cases, the molar thiol : ClO ratio was 1 : 0.5; the
yields of the corresponding disulfides were 96 to 98%.
2
C. Dihexyl disulfide (2b). A solution of thiol 2 (0.5 g,
.2 mmol) in hexane (5 mL) was mixed with aqueous ClO2
Experimental
4
(
0.143 g, 2.1 mmol). The reaction mixture was magnetically
stirred at 20 °C for 3 h. After the reaction was completed (deꢀ
coloration of the solution), the organic phase was separated
on a separating funnel, and the solvent was removed to give
dihexyl disulfide 2b (0.49 g, 98%), b.p. 71—73 °С (2 Torr).
Commercial thiols 1a—c (99% purity) were used as purꢀ
chased. Aqueous ClO was a commercial product; the concenꢀ
2
tration of ClO in the initial solution was determined by titraꢀ
2
7
tion according to a known procedure.
Found (%): C, 61.46; H, 11.26; S, 27.28. C H S . Calcuꢀ
TLC was carried out on Silufol plates; spots were visualized
with aqueous 5% KMnO4 acidified with several drops of
conc. H SO . Eluents were light petroleum—Et O (7 : 3) for 1a,
12 26 2
lated (%): C, 61.54; H, 11.11; S, 27.35. MS (EI, 70 eV),
+
+
m/z (Irel (%)): 234 [M] (19); 150 [С H SSH] (17); 117
6
13
+
2
4
2
+
+
+
[
С H S] (11); 85 [С H ] (24); 57 [C H ] (16); 55 [С H ]
6 13 6 13 4 9 4 7
Me CO—heptane (2 : 3) for 1b, and Me CO—heptane (5 : 1)
2
2
+
(
16); 43 [С H ] (100).
for 1c.
3
7
GLC analysis was performed with a Chromꢀ5 chromatoꢀ
graph (flame ionization detector, column 3×3000 mm, SKTFꢀ50
This work was financially supported by the Russian
Foundation for Basic Research (Ural Regional Project
No. 01ꢀ03ꢀ96404).
*
For Part 1, see Ref. 1.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1779—1780, August, 2003.
066ꢀ5285/03/5208ꢀ1877 $25.00 © 2003 Plenum Publishing Corporation
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