acetyl Methanesulfonate

Purification Methods

The main impurity is methanesulfonic acid. Reflux it with redistilled acetyl chloride for 6-10hours, i.e. until no further HCl is absorbed in a trap, and exclude moisture. Distil off excess of AcCl and carefully distil it below 0.001mm with the bath temperature below 120o to give the anhydride as a pale yellow oil which solidifies below 0o. Below ~130o it gives the disulfonic anhydride, and above ~130o polymers are formed, and it is used for cleaving ethers [Preparation, IR, NMR: Karger & Mazur J Org Chem 36 528, 532 1971]. [Beilstein 2 H 166, 2 III 349.]