Efficient use of trimethylsulfonium methylsulfate as a reagent for the epoxidation of carbonyl-containing compounds

A process for the efficient conversion of trimethylsulfonium methylsulfate into dimethylsulfonium methanide, thence epoxides, has been devised. Thus d imethyl sulfate and dimethyl sulfide are caused to react in the presence of either a mineral acid or an organic acid. The anion of trimethylsulfonium methyl sulfate is converted by the acid into methyl hydrogen sulfate, which in turn reacts with excess dimethyl sulfide to form trimethylsulfonium hyd rogen sulfate. The outcome is that both methyl groups of dimethyl sulfate a re converted into the desired trimethylsulfonium salt, thence dimethylsulfo nium methanide; the process is mediated by low boiling dimethyl sulfide whi ch can be recycled, and the by-product (K2SO4) is more easily disposed of t han potassium methyl sulfate.