A convenient method for the preparation of methanesulfonyl chloride-d3 is described. The procedure consists of the anhydrous chlorination of dimethyl sulfoxide-d6 with chlorine and the aqueous chlorination. Methanesulfonyl chloride-d3 was obtained in a 52% yield, and a small amount of dimethyl sulfone-d6 was also isolated. Trichloromethyl methyl sulfide (-d3) was found to be one of the intermediates in this reaction.
