Synthesis of methanesulfonyl chloride (MSC) from methane and sulfuryl chloride

Article abstract of DOI:10.1039/b314160h

Methane is transformed selectively to methanesulfonyl chloride at low temperature by liquid-phase reaction of methane with SO₂Cl ₂ in the presence of a free radical initiator and a promoter using 100% H₂SO₄ as the solvent.

Full text of DOI:10.1039/b314160h

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Synthesis of methanesulfonyl chloride (MSC) from methane and sulfuryl
chloride
Sudip Mukhopadhyay,a Mark Zerella,a Alexis T. Bell,*a R. Vijay Srinivasb and Gary S. Smithb
a Department of Chemical Engineering, University of California, Berkeley, CA 94720, USA.
E-mail: bell@cchem.berkeley.edu; Fax: 1 510 642 4778; Tel: 1 510 642 1536
b ATOFINA Chemicals, Inc., King of Prussia, PA 19406, USA
Received (in Cambridge, UK) 5th November 2003, Accepted 18th December 2003
First published as an Advance Article on the web 27th January 2004
Methane is transformed selectively to methanesulfonyl chloride
at low temperature by liquid-phase reaction of methane with
SO2Cl2 in the presence of a free radical initiator and a promoter
using 100% H2SO4 as the solvent.
SO2Cl2, and defined as the ratio of the moles of SO2Cl2 converted
to MSC to the moles of SO2Cl2 fed initially to the reactor.
Table 1 shows the effect of different initiators on the conversion
of SO2Cl2 to MSC. In the absence of an initiator, no MSC was
formed. Each of the initiators used activated methane; however, the
highest activity obtained using urea–H2O2 in combination with
RhCl3. Almost 26% of the SO2Cl2 was converted to MSC in this
case. The least active initiator was K4P2O8. Using this material,
only 12% of the SO2Cl2 were converted to MSC.
Table 2 shows the effect of different process parameters on the
rate of methane sulfonation using urea–H2O2 as the initiator and
RhCl3 as the promoter. Increasing the CH4 pressure from 300 to
700 psig increased the conversion of SO2Cl2 to MSC from 4 to
26%. However, increasing the amount of SO2Cl2 did not affect the
conversion of SO2Cl2 to MSC. The conversion of SO2Cl2 to MSC
increased from 14 to 26% when the temperature was raised from 50
to 60 °C. However, at 75 °C, only 18% of SO2Cl2 was converted to
MSC. The low conversion at this temperature may be due to the
evaporation of SO2Cl2 from the glass liner and its condensation
between the liner and the autoclave walls during the course of the
reaction. Consistent with this interpretation, a large quantity of
SO2Cl2 (bp 68–70 °C) was observed at the bottom of the autoclave
after 12 h of reaction.
Methanesulfonyl chloride (MSC)1 is a versatile reagent that can be
used to introduce mesyl groups (CH3SO22) via substitution of
hydroxyl and amino groups, and active a-hydrogens. MSC is
widely used as an intermediate in the synthesis of photographic
chemicals, agrochemicals, and pharmaceutical intermediates, as
well as a stabilizer and catalyst. It is also widely known as a curing
and chlorinating agent and as a precursor to methanesulfonic acid
(MSA).2 The commercial process for the production of MSC
involves the oxidative chlorination of methylmercaptan or dime-
thyldisulfide in concentrated HCl.3 Since these starting materials
are expensive and toxic, there is an incentive to look for an
alternative process. The use of methane, the main component of
natural gas, as a starting material is particularly attractive, since
methane is an abundant, low-cost carbon feed stock.
In this communication, we show that MSC can be synthesized in
high yield by the reaction of methane and sulfuryl chloride,
SO2Cl24 at low temperature (Scheme 1).
In a typical reaction5 (Scheme 1) methane was reacted with
6
SO2Cl2 in 100% H2SO4 to form MSC in the presence of an
The reaction requires a highly acidic solvent (see Table 2). When
the reaction was carried out in H2SO4, the conversion of SO2 to
initiator in a high-pressure, glass-lined, Parr autoclave. Reactions
were carried out for 12 h at 60 °C. 1H and 13C NMR were used to
confirm that MSC is the only liquid-phase product generated from
methane in the presence of SO2Cl2. No reaction occurred in the
absence of methane, indicating that the source of the methyl group
in the product is methane. Analysis of the gas phase shows that
CH3Cl was formed as the primary by-product. The other by-
products were traces of polychlorinated hydrocarbons.
Table 1 Effect of different initiators on the MSC synthesisa
Conv. of
Amount/
mmol
SO2Cl2 to
Promoter MSC/mmol MSC (%)
No.
Initiator
1
2
3
4b
K4P2O8
K2S2O8
Urea–H2O2 0.4
Urea–H2O2 0.4
0.4
0.4
None
None
None
RhCl3
0.9
1.2
1.3
1.9
12
16
18
26
1
Fig. 1 shows H and 13C NMR spectra of the reaction product.
The 1H NMR peak at 3.65 ppm and the 13C NMR peak at 52.78 ppm
are characteristic of the methyl group in CH3SO2Cl. Absence of
1
any other peaks both in the H and 13C NMR indicates that there
a Reaction conditions: methane, 700 psig (193 mmol); SO2Cl2, 1 g (7.4
mmol); initiator, 0.4 mmol; molar ratio of methane to SO2Cl2, 26; solvent,
100% H2SO4, 3 mL; temperature, 60 °C; time, 12 h. b RhCl3, 0.1 mmol.
were no other products formed in the liquid phase.
Conversions are reported on the basis of the limiting reagent,
Table 2 Effect of process parameters on the sulfonation reactiona
Conv. of
SO2Cl2/
CH4/psig mmol
MSC/ SO2Cl2 to
mmol MSC (%)
Scheme 1 Direct reaction of methane with SO2Cl2.
No.
T/°C
Solvent
1
2
3
4
5
6
7
8
9
300
500
700
700
700
700
700
700
700
700
7.4
7.4
7.4
6
60
60
60
60
60
50
75
60
60
60
H2SO4
H2SO4
H2SO4
H2SO4
H2SO4
H2SO4
H2SO4
MSAb
0.3
0.8
1.9
1.5
1.9
1.0
1.3
0.6
4
11
26
25
26
14
18
8
10
7.4
7.4
7.4
7.4
7.4
TFMSAc 0.9
SO2Cl2 0.4
28
5
10
a Reaction conditions: urea–H2O2, 0.4 mmol; RhCl3, 0.1 mmol; time, 12 h;
solvent, 3 mL. b MSA is methanesulfonic acid. c TFMSA is trifluor-
omethanesulfonic acid.
Fig. 1 1H and 13C NMR of the reaction mixture.
472
C h e m . C o m m u n . , 2 0 0 4 , 4 7 2 – 4 7 3
T h i s j o u r n a l i s © T h e R o y a l S o c i e t y o f C h e m i s t r y 2 0 0 4

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MSC was 26%, and it was 28% when trifluorormethanesulfonic
acid (TFMSA) was used as the solvent. However, only an 8%
conversion of SO2Cl2 to MSC was achieved in MSA, and in
SO2Cl2, a 5% conversion of SO2Cl2 to MSC is obtained after 12 h
of reaction.
Notes and references
1 (a) M. L. Wolfrom, J. C. Sowden and E. A. Metcalf, J. Am. Chem. Soc.,
1941, 63, 1688; (b) N. D. Pelikh and Sakhar, Khim. Ref. Zh., 1938, 1, 45;
(c) R. W. Roberts, J. Am. Chem. Soc., 1957, 79, 1175; (d) W. A. Proell,
US 2489317, 1949; (e) P. J. Hearst and C. R. Noller, Org. Synth., 1950,
30, 58; (f) J. H. Looker, J. Org. Chem., 1952, 17, 510; (g) F. A.
Drahowzal, Org. Sulfur Compd., 1961, 1, 361; (N. Kharasch, ed.); (h) W.
E. Truce and C. W. Vriesen, J. Am. Chem. Soc., 1953, 75, 5032.
2 (a) N. Basickes, T. E. Hogan and A. Sen, J. Am. Chem. Soc., 1996, 118,
13111; (b) S. Mukhopadhyay and A. T. Bell, Ind. Eng. Chem Res., 2002,
41, 5901; (c) S. Mukhopadhyay and A. T. Bell, Angew. Chem., Int. Ed.,
2003, 42, 1019; (d) S. Mukhopadhyay and A. T. Bell, Angew. Chem., Int.
Ed., 2003, 42, 2990; (e) S. Mukhopadhyay and A. T. Bell, J. Am. Chem.
Soc., 2003, 125, 4406; (f) S. Mukhopadhyay and A. T. Bell, Chem.
Commun., 2003, 1590; (g) Also see, for the first catalytic alkane
sulfonation, Y. Ishii, K. Matsunaka and S. Sakaguchi, J. Am. Chem. Soc.,
2000, 122, 7390.
3 (a) H. Gongora and J. Tournier-Lasserve, EP 40560, 1981; (b) G.
Henning, E. Stroefer and E. Freudenthaler, DE 10037507, 2002; (c) R. M.
Guertin, DE 1811768, 1969; (d) S. L. Giolito and H. O. Hofmann, US
3600136, 1968; (e) S. L. Giolito and H. O. Hofmann, US 3993692, 1966;
(f) K. Ishita, R. Orita and S. Tanaka, JP 52008283, 1969; (g) F. Hubenett,
EP 10162, 1980; (h) A. Husain and G. A. Wheaton, EP 313939, 1989; (i)
D. M. Gardner and G. A. Wheaton, EP 331864, 1989.
4 SO2Cl2 can be easily synthesized by a catalytic reaction of SO2 and Cl2,
see (a) W. V. Cicha and L. E. Manzer, US 5879652, 1999; (b) W. V.
Cicha and L. E. Manzer, US 5759508, 1998; (c) E. G. Nikolev, S. D.
Danilov, E. A. Vinogradov, E. M. Veselova, I. Vasil’ev and G. V.
Prokoshina, SU 1717535, 1990.
5 In a 100 mL glass-lined, Parr autoclave reactor, 0.4 mmol initiator, 7.4
mmol SO2Cl2 and 3 mL 100% H2SO4 were charged together with a small
Teflon-coated magnetic stir bar. N2 was bubbled through the reactor to
remove any air from the system. The reactor was pressurized with 700
psig of methane and then heated to 60 °C under stirring for 12 h. After the
stipulated period of time, the reactor was cooled to room temperature,
vented, and opened to collect the reaction mixture. The mixture was
analyzed by 1H and 13C NMR analysis. A mixture of D2O and H2O in a
capillary was used as the lock and reference. The corresponding 1H
chemical shift of the methyl group in MSC was d 3.6 to 3.75, depending
on the concentration of MSC in the mixture.
In a separate set of reactions MSC was hydrolyzed completely
with water to MSA at 50 °C for 2 h.7 The only by-product was HCl
which can be separated easily by distillation. The chemical shift
(using D2O as the NMR solvent) for the methyl group of MSA was
2.97 ppm in the 1H NMR and 39.5 ppm in the 13C NMR.
The synthesis of MSC is believed to proceed via a free radical
pathway2 as written in Scheme 2. This scheme is supported by the
observation that in the presence of O2, no MSC is formed. Since O2
is a well-known free radical scavenger, it is inferred that MSC
formation involves free radicals. Further supporting this idea is the
observation that in the absence of SO2Cl2, C2H6 is observed as a
result of the coupling of two methyl radicals. The presence of trace
amounts of polychlorinated impurities ( < 0.5%) in the head space
of the autoclave strongly suggests the radical initiated chlorination
of methane and ethane. The reaction is assumed to start with the
abstraction of hydrogen from methane molecules by the initiator
species I·, where I· can be SO42·, PO422·, OH·, RhO· or RhOO·.
The methyl radical thus formed then reacts with SO2Cl2 to form
CH3SO2Cl and Cl·. Cl· radicals can then abstract hydrogen from
methane to generate CH3· radicals and HCl. Reaction (1) is the
initiation step; whereas, reactions (2) and (3) are the propagation
steps. Reaction (4) is a radical termination step. Also though not
written, two CH3· radicals can couple to form C2H6.
In conclusion, we have developed a highly selective, low-
temperature approach for the synthesis of MSC involving the
reaction of methane and SO2Cl2. MSC is a low boiling liquid (bp
60°/21 mm Hg) that can be isolated readily by distillation from the
reaction mixture. The reaction is highly selective, and as much as
26% of the SO2Cl2 charged is converted to MSC at 60 °C using
sulfuric acid as the solvent. The MSC thus formed can be isolated
and hydrolyzed with water to MSA, which is also a valuable
product.
6 100% H2SO4 was prepared in the laboratory by adding SO3 (Aldrich) to
a stock solution of concentrated H2SO4 (Aldrich).
ATOFINA Chemicals, Inc., North America, funded this study.
7 The synthesis of MSC (bp 60°/21 mm Hg) from methane and SO2Cl2 and
subsequent hydrolysis to MSA has an advantage over the direct free-
radical initiated methane sulfonation with SO3 in fuming sulfuric acid,
since it avoids the difficult distillation of MSA from sulfuric acid. Such
distillation must be performed under vacuum, since MSA (bp 167°/10
mm Hg) decomposes to a mixture of CH3SO3CH3, SO2 and H2O at
around 180 °C.
Scheme 2 Proposed reaction mechanism.
C h e m . C o m m u n . , 2 0 0 4 , 4 7 2 – 4 7 3
473