Methyl fluorosulfonate

Methyl fluorosulfonate, (also known as magic methyl, a name coined by George Olah) has the chemical formula F-SO2-OCH3. It is used as a powerful (about four orders of magnitude more reactive than methyl iodide) methylating reagent.

Methyl fluorosulfonate is prepared by distillation from an equimolar mixture of fluorosulfonic acid and dimethyl sulfate.

The compound is acutely toxic (LD50 (rat) ~ 5 ppm), causing irritation of the respiratory tract and pulmonary edema, presumably through alkylation of lipids in the cell membranes.