Org. Synth. 2002, 78, 99
DOI: 10.15227/orgsyn.078.0099
REDUCTION OF SULFONYL HALIDES WITH ZINC POWDER: S-METHYL
METHANETHIOSULFONATE
[
Methanesulfonothioic acid, S-methyl ester
]
Submitted by Fabrice Chemla
1
and Philippe Karoyan
2
.
Checked by Mitsuru Kitamura and Koichi Narasaka.
1. Procedure
CAUTION: The reaction must be performed in a well-ventilated hood.
A 1-L, three-necked, round-bottomed flask equipped
with a large magnetic stirring bar, a thermometer,
reflux condenser, and a 100-mL pressure-equalizing
addition funnel with a rubber septum is charged
with
49 g
(0.75 mol) of zinc
dust,
1.0 mL (0.012 mol)
of 1,2-dibromoethane
,
2.0
mL
(0.016 mol) of chlorotrimethylsilane
,
and
500 mL of ethyl acetate
(Note 1). After the mixture is stirred for 15 min at room temperature,
it is heated to reflux by means of an oil bath and
38.7 mL
(0.500 mol) of methanesulfonyl
chloride
(Note 2) is added dropwise through
the addition funnel. The reaction is highly exothermic. At
the end of the addition (1 hr), a large part of the zinc is consumed.
The resulting grey suspension is stirred for an additional 15 min.
Acetyl
chloride, 35.7 mL
(0.502 mol)
,
(Note 2) is then added dropwise (
CAUTION : Note
3
) through the addition
funnel with care taken to maintain vigorous stirring of the reaction mixture.
After completion of the addition, the resulting mixture becomes clear and no zinc
remains. Heating is maintained for an additional 15 min, and the mixture is allowed
to cool to room temperature. The resulting clear solution is poured into a 1 M aqueous hydrochloric acid solution (ca. 200
mL) and the phases are separated. The aqueous phase is extracted
with
ethyl acetate (ca. 200
mL) and the combined organic phases are washed with
brine (ca. 200 mL)
and dried over anhydrous magnesium sulfate
.
The solvent is removed under reduced pressure and the residual yellow oil is distilled
under reduced pressure to give 24.1 g
(76% yield) of
methyl methanethiosulfonate
(Note 4) as a colorless liquid, bp
80-83°C/0.5 mm.
2. Notes
1.
Zinc dust (<10
micron) was purchased from Aldrich Chemical Company, Inc.
1,2-Dibromoethane and chlorotrimethylsilane
were purchased from Acros Chemicals or Tokyo Chemical
Industry Co.
and used as received.
Ethyl
acetate was purchased from Merck (HPLC grade)
and used without any purification.
2.
Methanesulfonyl chloride
and
acetyl chloride were purchased from
Acros Chemicals, Tokyo Chemical Industry Co.,
and Wako Pure Chemical Industries, Ltd.
and used as
received.
3.
The reaction is highly exothermic. The addition rate is approximately
one drop per two seconds, in order to achieve addition within approximately 1 hr.
The reaction mixture must be well-stirred and maintained at reflux during this period
to avoid any uncontrolled event.
4.
The product exhibits the following physical and spectral properties:
1H NMR (CDCl
3,
400 MHz) δ: 2.70 (s, 3 H), 3.32 (s, 3 H)
;
13C NMR (CDCl
3,
126 MHz) δ: 18.2. 48.8
; IR (film) cm
−1: 3030 (weak), 3010
(weak), 2930 (weak), 1430 (medium), 1410 (medium),
1330 (strong), 1300 (strong), 1130 (strong),
960 (strong), 750 (strong)
. Microanalysis: Calcd
for C
2H
6O
2S
2: C, 19.04; H, 4.76. Found:
C, 18.99; H, 4.91.
Handling and Disposal of Hazardous Chemicals
The procedures in this article are intended for use only by persons with prior training in experimental organic chemistry. All hazardous materials should be handled using the standard procedures for work with chemicals described in references such as "Prudent Practices in the Laboratory" (The National Academies Press, Washington, D.C., 2011 www.nap.edu). All chemical waste should be disposed of in accordance with local regulations. For general guidelines for the management of chemical waste, see Chapter 8 of Prudent Practices.
These procedures must be conducted at one's own risk. Organic Syntheses, Inc., its Editors, and its Board of Directors do not warrant or guarantee the safety of individuals using these procedures and hereby disclaim any liability for any injuries or damages claimed to have resulted from or related in any way to the procedures herein.
3. Discussion
Thiosulfonic S-esters
3 are powerful sulfenylating reagents,
4
more reactive than the commonly used disulfides, and more stable than the very reactive
sulfenyl halides. In addition, they have found wide industrial applications as biologically
active compounds or in polymer production.
3 Their use,
however, has been limited by the lack of easy and practical preparations.
S-Methyl methanethiosulfonate
is commercially available, but is expensive. Other preparation methods involve oxidation
of thiols or disulfides by halogens or peroxides,
3
reduction of sulfinyl halides
5 (which have to be prepared) or sulfonyl
halides with
potassium iodide
6
or
copper/bronze
7 as well as thermolysis of sulfonylhydrazines.
8
Finally, a two-day procedure for the preparation of
methyl
methanethiosulfonate
has been reported from
dimethyl
sulfoxide.
9
The reaction described above has been successfully applied to the preparation of
various symmetrical thiosulfonic S-esters (Table).
10 The procedure described here
gives better and more reproducible results than the one reported before.
10
TABLE10
PREPARATION OF SYMMETRICAL THIOSULFONATES
FROM SULFONYL CHLORIDES
|
|
|
Starting Material
|
Product
|
Yield
|
|
|
1
|
|
|
90 %
|
|
2
|
|
|
90 %
|
|
3
|
|
|
44 %
|
|
4
|
|
|
65 %
|
|
5
|
|
|
60 %
|
|
Appendix
Chemical Abstracts Nomenclature (Collective Index Number);
(Registry Number)
Zinc (8,9); (7440-66-6)
S-Methyl methanethiosulfonate:
Methanesulfonic
acid, thio-, S-methyl ester (8);
Methanesulfonothioic acid, S-methyl
ester (9); (2949-92-0)
1,2-Dibromoethane:
Ethane, 1,2-dibromo-,
(8,9); (106-93-4)
Chlorotrimethylsilane:
Silane, chlorotrimethyl-,
(8,9); (75-77-4)
Methanesulfonyl chloride (8,9); (124-63-0)
Acetyl chloride (8,9); (75-36-5)
Copyright © 1921-, Organic Syntheses, Inc. All Rights Reserved