Methanesulfonyl chloride

Methanesulfonyl chloride
IUPAC name Methanesulfonyl chloride
Other names Mesyl chloride
Identifiers
CAS number	124-63-0 Y
ChemSpider	29037 N
Jmol-3D images	Image 1
SMILES CS(Cl)(=O)=O
Properties
Molecular formula	CH3ClO2S
Molar mass	114.56 g/mol
Appearance	liquid
Density	1.480 g/mL
Boiling point	161 °C (730 mm Hg)
Hazards
Main hazards	Lachrymator, Highly toxic, corrosive
N (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Methanesulfonyl chloride is a compound containing a sulfonyl chloride used to make methanesulfonates and to generate sulfene.

Preparation, manufacture and handling

Methanesulfonyl chloride is highly toxic, moisture sensitive, corrosive, and a lachrymator. It should be stored in a dry location, preferably in a desiccator. It is manufactured either via direct synthesis from methane and sulfuryl chloride in a radical reaction (1):

CH_{4 (g)} + SO₂Cl_{2 (g)} → CH₃SO₂Cl + HCl _(g) (1)

other method of manufacture starts with methanesulfonic acid, which is accessible out of methane and sulfur trioxide (2) or by vigorous oxidation of methanethiol (3):

CH_{4 (g)} + SO_{3 (g)} → CH₃SO₃H _(l) (2)

CH₃SH + HNO₃ → CH₃SO₃H + H₂O + NO_x (3)

The methanesulfonic acid prepared is reacted with thionyl chloride (4) or phosgene (5) to form mesyl chloride:

CH₃SO₃H + SOCl₂ → CH₃SO₂Cl + SO₂ + HCl (4)

CH₃SO₃H + COCl₂ → CH₃SO₂Cl + CO₂ + HCl (5)

Applications

Methanesulfonates

The main use of methanesulfonyl chloride is the formation of methanesulfonates from alcohols in the presence of a non-nucleophilic base.^[1] Methanesulfonates are used as intermediates in substitution reactions, elimination reactions, reductions, and rearrangement reactions. When treated with a Lewis acid, oxime methanesulfonates will undergo a facile Beckmann rearrangement.^[2]

Methanesulfonates have been occasionally used as a protecting group for alcohols. It is stable to acidic conditions and is cleaved back to the alcohol using sodium amalgam.^[3]

Methanesulfonamides

Methanesulfonyl chloride will react with amines to form a methanesulfonamide. Unlike a methanesulfonate, a methanesulfonamide is a very stable functional group under both acidic and basic conditions. When used as a protecting group, they can be converted back to amines using lithium aluminium hydride or a dissolving metal reduction.^[4]

Addition to alkynes

In the presence of copper(II) chloride, methanesulfonyl chloride will add across alkynes to form β-chloro sulfones.^[5]

Formation of heterocycles

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.^[6]

Miscellaneous

Forming acyliminium ions from α-hydroxyamides can be done using methanesulfonyl chloride and a base, typically triethylamine.^[7]

References

1. ^ 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. 
2. ^ 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. 
3. ^ 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. 
4. ^ 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. 
5. ^ Amiel, Y. (1971). "Addition of sulfonyl chlorides to acetylenes". Tetrahedron Lett. 12 (8): 661. doi:10.1016/S0040-4039(01)96524-4. 
6. ^ 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. 
7. ^ 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.