5539-53-7

Acetyl Methanesulfonate, is an impurity of Busulfan (B689900), an alkylating agent with antileukemic activity. Antineoplastic.

Preparative Methods: Acetyl Methanesulfonate can be prepared on a large scale (1 mol) from Acetyl Chloride and Methanesulfonic Acid by heating at reflux followed by fractional distillation (85% yield).

Handling, Storage, and Precautions: slightly hygroscopic. However, no particular precautions are required  upon exposure to air for a short period of time. acetyl Methanesulfonate is stable if stored at 4 °C for several months. Use in a fume hood.

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.]