Methanesulfonic anhydride

Chemical properties

white to light brown to grey powder, crystals and/

The Uses of Methanesulfonic anhydride

Methanesulfonic anhydride is used to prepare methylsulfonyl esters called as mesylates. It finds application in the reaction of aromatic alkylation. It reacts with dimethylsulfoxide to get sulfoxonium complex, which is a useful oxidizing agent.

Preparation

Methanesulfonic anhydride may be prepared by the dehydration of methanesulfonic acid with phosphorus pentoxide.
P2O5 + 6 CH3SO3H → 3 (CH3SO2)2O + 2 H3PO4
Methanesulfonic anhydride can be purified by distillation under vacuum (distillation of a solid) or by recrystallized from Methyl tert-butyl ether/toluene.

Safety

Not only is Methanesulfonic anhydride corrosive, posing potential risks to skin, eyes, and mucous membranes, but it is also sensitive to moisture. As a hygroscopic substance, exposure to water can lead to degradation, compromising its efficacy and safety. Therefore, meticulous storage conditions are paramount to ensure the stability of the compound. To safeguard the integrity of methanesulfonic anhydride, storing it in a cool and dry environment is recommended. The storage facility should be adequately ventilated to prevent the accumulation of vapors and maintain optimal conditions for the compound. Furthermore, the storage containers must be tightly sealed to prevent moisture ingress and subsequent degradation.

Reactions

Passage of hydrogen chloride through molten methanesulfonic anhydride yields MsCl.

Similar to MsCl, methanesulfonic anhydride 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. Unlike MsCl, Ms2O may not be suitable for mesylation of the unsaturated alcohols.