Methanesulfonyl chloride

Methanesulfonyl chloride, commonly abbreviated as MsCl and also known as mesyl chloride or methyl sulfochloride, is a reactive sulfonylating agent with CAS number 124-63-0. It belongs to the class of sulfonyl chlorides and is handled as a corrosive, moisture-sensitive reagent in controlled laboratory and industrial environments.

In pharmaceutical synthesis, MsCl converts hydroxyl groups into mesylate leaving groups, enabling nucleophilic substitution reactions that would otherwise be unfeasible on unactivated alcohols. This activation step is critical in active pharmaceutical ingredient manufacturing, particularly in producing chiral intermediates and agrochemical building blocks where precise stereochemical control is required.

Methanesulfonyl chloride is supplied for industrial and research applications under REACH-compliant conditions within the European market. It is available in standard reagent and technical grades, typically packaged in moisture-proof containers suited to its sensitivity. Procurement teams should confirm SDS documentation and transport classification prior to ordering.