methanesulfonic anhydride

Ms₂O may be prepared by the dehydration of methanesulfonic acid with phosphorus pentoxide.

:P₂O₅ + 6 CH₃SO₃H → 3 (CH₃SO₂)₂O + 2 H₃PO₄

Ms₂O can be purified by distillation under vacuum (distillation of a solid) or by recrystallization from Methyl tert-butyl ether/toluene.

Passage of hydrogen chloride through molten Ms₂O yields MsCl.{{cite journal |last1=Field |first1=Lamar |last2=Settlage |first2=Paul H. |title=Reaction of Methanesulfonic Anhydride with Hydrogen Halides 1 |journal=Journal of the American Chemical Society |date=January 1955 |volume=77 |issue=1 |pages=170–171 |doi=10.1021/ja01606a053 |bibcode=1955JAChS..77..170F |url=https://pubs.acs.org/doi/10.1021/ja01606a053 |language=en |issn=0002-7863}}

Similar to MsCl, Ms₂O can perform mesylation of alcohols to form sulfonates. Use of Ms₂O avoids the alkyl chloride, which often appears as a side-product when MsCl is used.{{cite journal |last1=Baumann |first1=W. J. |last2=Jones |first2=L. L. |last3=Barnum |first3=B. E. |last4=Mangold |first4=H. K. |title=The formation of alkyl and alkenyl methanesulfonates and their reduction to hydrocarbons |journal=Chemistry and Physics of Lipids |date=1 November 1966 |volume=1 |issue=1 |pages=63–67 |doi=10.1016/0009-3084(66)90008-9 |url=https://www.sciencedirect.com/science/article/abs/pii/0009308466900089 |language=en |issn=0009-3084}} Unlike MsCl, Ms₂O may not be suitable for mesylation of the unsaturated alcohols.{{cite journal |last1=Cegla |first1=Gad |last2=Mangold |first2=Helmut K. |title=A new procedure for the preparation of alkyl methanesulfonates |journal=Chemistry and Physics of Lipids |date=1 May 1973 |volume=10 |issue=4 |pages=354–355 |doi=10.1016/0009-3084(73)90059-5 |url=https://www.sciencedirect.com/science/article/abs/pii/0009308473900595 |language=en |issn=0009-3084}}

Examples of mesylation of alcohols with Ms₂O:

• Octadecyl methanesulfonate was prepared from octadecanol in pyridine.
• Secondary alcohol at the anomeric carbon of 2,3,4,5-O-Benzyl-protected glucose reacted to form a glycosyl mesylate, which was found to be more stable than its triflate counterpart, in 2,4,6-collidine.{{cite journal |last1=Leroux |first1=Jacques |last2=Perlin |first2=Arthur S. |title=Synthesis of glycosyl halides and glycosides via 1-O-sulfonyl derivatives |journal=Carbohydrate Research |date=1 November 1978 |volume=67 |issue=1 |pages=163–178 |doi=10.1016/S0008-6215(00)83739-8 |url=https://www.sciencedirect.com/science/article/abs/pii/S0008621500837398 |language=en |issn=0008-6215}}

Ms₂O also converts amines to sulfonamides.{{cite journal |last1=Lis |first1=Randall |last2=Morgan |first2=Thomas K. |last3=Marisca |first3=Anthony J. |last4=Gomez |first4=Robert P. |last5=Lind |first5=Joan M. |last6=Davey |first6=David D. |last7=Phillips |first7=Gary B. |last8=Sullivan |first8=Mark E. |title=Synthesis of novel (aryloxy)propanolamines and related compounds possessing both class II and class III antiarrhythmic activity |journal=Journal of Medicinal Chemistry |date=October 1990 |volume=33 |issue=10 |pages=2883–2891 |doi=10.1021/jm00172a033 |pmid=1976812 |url=https://doi.org/10.1021/jm00172a033 |language=en |issn=0022-2623}}

Assisted by Lewis acid catalyst, Friedel-Crafts methylsulfonation of aryl ring can be achieved by Ms₂O. In contrast to MsCl, either activated or deactivated benzene derivatives can form the corresponding sulfonatesin satisfactory yields with Ms₂O.{{cite journal |last1=Vaillancourt |first1=Valerie |last2=Cudahy |first2=Michele M. |title=Methanesulfonic Anhydride |journal=Encyclopedia of Reagents for Organic Synthesis |date=15 April 2001 |pages=rm068 |doi=10.1002/047084289x.rm068 |url=https://onlinelibrary.wiley.com/doi/10.1002/047084289X.rm068 |publisher=John Wiley & Sons, Ltd |isbn=0-471-93623-5 |language=en}}

Examples of aromatic sulfonation with Ms₂O:

• Sulfonation of chlorobenzene resulted in addition of methylsulfonyl group at para and ortho positions (with respect to chloride), with a ratio of 2 to 1, respectively; while reaction with Meta-dichlorobenzene gave monosulfonylated product at C4 position.
• With sulfuric acid, di-aryl sulfones were synthesized.{{cite journal |last1=Tyobeka |first1=Themba E. |last2=Hancock |first2=Richard A. |last3=Weigel |first3=Helmut |title=Novel sulphonylating reagent: sulphuric acid–hexafluoroacetic anhydride |journal=Journal of the Chemical Society, Chemical Communications |date=1 January 1980 |issue=3 |pages=114–115 |doi=10.1039/C39800000114 |url=https://pubs.rsc.org/en/content/articlelanding/1980/c3/c39800000114 |language=en |issn=0022-4936}}

Ms₂O catalyzes the esterification of alcohols by carboxylic acids. 2-Naphthyl acetate was prepared from 2-naphthol and glacial (anhydrous) acetic acid in the presence of Ms₂O. Both alcohols on ethylene glycol successfully benzoylated with benzoic acid and Ms₂O. However, for free alcohols on monosaccharides, the acetylation was not completed.

Like Pfitzner–Moffatt oxidation and Swern oxidation, with DMSO, Ms₂O can oxidize primary and secondary alcohols to aldehydes and ketones, respectively, in HMPA.{{cite journal |last1=Albright |first1=J. Donald |title=Sullfoxonium salts as reagents for oxidation of primary and secondary alcohols to carbonyl compounds |journal=The Journal of Organic Chemistry |date=June 1974 |volume=39 |issue=13 |pages=1977–1979 |doi=10.1021/jo00927a054 |url=https://pubs.acs.org/doi/pdf/10.1021/jo00927a054 |language=en |issn=0022-3263}} This method applies to benzylic alcohol. HMPA may be substituted by dichloromethane but may result in more side-products.

• Methanesulfonyl chloride
• Disulfuric acid
• Sodium pyrosulfate
• Acetic anhydride
• Trifluoromethanesulfonic anhydride

{{Reflist}}

Category:Acid anhydrides

Category:Reagents for organic chemistry

Category:Methyl compounds