Methanesulfonyl chloride is used as a reagent for conversion of alcohols to mesylate esters such as methanesulfonate, which is an intermediate in substitution reactions, elimination reactions, reductions, and rearrangement reactions viz. Beckmann rearrangement. It is an electrophile and acts as a source of CH₃SO₂⁺ group. It is also used to prepare beta-chloro sulfones, methanesulfonamide and heterocyclic compounds containing five membered sultones.

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