Methanesulfonyl chloride

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Methanesulfonyl chloride
Methanesulfonyl Chloride Structural Formulae.svg
IUPAC name
Methanesulfonyl chloride
Other names
Mesyl chloride
3D model (JSmol)
ECHA InfoCard 100.004.279
Molar mass 114.54 g·mol−1
Appearance colorless liquid
Density 1.480 g/mL
Boiling point 161 °C (322 °F; 434 K) 730 mmHg
Main hazards Lachrymator, highly toxic, corrosive
Related compounds
Other anions
Methanesulfonyl fluoride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Methanesulfonyl chloride (mesyl chloride) is an organosulfur compound with the formula CH3SO2Cl. It is a colourless liquid that dissolves in polar organic solvents but is reactive toward water, alcohols, and many amines. The simplest organic sulfonyl chloride, it is used to make methanesulfonates and to generate the elusive molecule sulfene.[3]


It is manufactured by the reaction of methane and sulfuryl chloride in a radical reaction:

CH4 + SO2Cl2 → CH3SO2Cl + HCl

Another method of manufacture entails chlorination of methanesulfonic acid with thionyl chloride or phosgene:

CH3SO3H + SOCl2 → CH3SO2Cl + SO2 + HCl
CH3SO3H + COCl2 → CH3SO2Cl + CO2 + HCl


Methanesulfonyl chloride is a precursor to many compounds because it is highly reactive. It is an electrophile, functioning as a source of the "CH3SO2+" group.[3]


Methanesulfonyl chloride is mainly used to give methanesulfonates by its reaction with alcohols in the presence of a non-nucleophilic base.[4] Methanesulfonates are used as intermediates in substitution reactions, elimination reactions, reductions, and rearrangement reactions. When treated with a Lewis acid, oxime methanesulfonates undergo facile Beckmann rearrangement.[5]

Methanesulfonates are occasionally used as a protecting group for alcohols. They are stable to acidic conditions and is cleaved back to the alcohol using sodium amalgam.[6]


Methanesulfonyl chloride react with primary and secondary amines to give methanesulfonamides. Unlike methanesulfonates, methanesulfonamides are very resistant toward hydrolysis under both acidic and basic conditions.[3] When used as a protecting group, they can be converted back to amines using lithium aluminium hydride or a dissolving metal reduction.[7]

Addition to alkynes[edit]

In the presence of copper(II) chloride, methanesulfonyl chloride will add across alkynes to form β-chloro sulfones.[8]

Formation of heterocycles[edit]

Upon treatment with a base, such as triethylamine, methanesulfonyl chloride will undergo an elimination to form sulfene. Sulfene can undergo cycloadditions to form various heterocycles. α-Hydroxyketones react with sulfene to form five-membered sultones.[9]


Forming acyliminium ions from α-hydroxyamides can be done using methanesulfonyl chloride and a base, typically triethylamine.[10]


Methanesulfonyl chloride is toxic and moisture sensitive, corrosive, and a lachrymator.


  1. ^
  2. ^
  3. ^ a b c Valerie Vaillancourt, Michele M. Cudahy, Matthew M. Kreilein and Danielle L. Jacobs "Methanesulfonyl Chloride" in E-EROS Encyclopedia for Reagents in Organic Synthesis. doi:10.1002/047084289X.rm070.pub2
  4. ^ Furst, A.; Koller, F. (1947). "Über Steroide und Sexualhormone. Ein neuer Weg zur Herstellung der α-Oxyde von Cholesterin und trans-Dehydro-androsteron". Helv. Chim. Acta. 30 (6): 1454. doi:10.1002/hlca.19470300609. 
  5. ^ Maruoka, K.; Miyazaki, T.; Ando, M.; Matsumura, Y.; Sakane, S.; Hattori, K.; Yamamoto, H. (1983). "Organoaluminum-promoted Beckmann rearrangement of oxime sulfonates". J. Am. Chem. Soc. 105 (9): 2831. doi:10.1021/ja00347a052. 
  6. ^ Webster, K. T.; Eby, R.; Schuerch, C. (1983). "Selective demesylation of 2-O-(methylsulfonyl)-?-mannopyranoside derivatives with sodium amalgam and 2-propanol". Carbohydr. Res. 123 (2): 335. doi:10.1016/0008-6215(83)88490-0. 
  7. ^ Merlin, P.; Braekman, J. C.; Daloze, D. (1988). "Stereoselective synthesis of (±)-tetraponerine-8, a defence alkaloid of the ant Tetraponera sp". Tetrahedron Lett. 29 (14): 1691. doi:10.1016/S0040-4039(00)82019-5. 
  8. ^ Amiel, Y. (1971). "Addition of sulfonyl chlorides to acetylenes". Tetrahedron Lett. 12 (8): 661. doi:10.1016/S0040-4039(01)96524-4. 
  9. ^ Potonay, T.; Batta, G.; Dinya, Z. (1988). "Flavonoids. 41. Stereospecific synthesis of 2,3-dihydro-c-3-substituted-t-3-methyl-r-2-phenyl-4H-1-benzopyran-4-ones". Journal of Heterocyclic Chemistry. 25: 343. doi:10.1002/jhet.5570250158. 
  10. ^ Chamberlin, A. R.; Nguyen, H. D.; Chung, J. Y. L. (1984). "Cationic cyclization of ketene dithioacetals. A general synthesis of pyrrolizidine, indolizidine, and quinolizidine alkaloid ring systems". J. Org. Chem. 49 (10): 1682. doi:10.1021/jo00184a002.