Methyl fluorosulfonate
# Methyl fluorosulfonate

Methyl fluorosulfonate, also known as magic methyl, is the organic compound with the formula $FSO_2OCH_3.$ It is a colorless liquid that is used as a strong methylating agent in organic synthesis. Because of its extreme toxicity, it has largely been replaced by the related reagent methyl trifluoromethanesulfonate.

## Synthesis and reactions

It is prepared by distillation of an equimolar mixture of fluorosulfonic acid and dimethyl sulfate. It was originally produced by the reaction of methanol with fluorosulfonic acid.

Methyl fluorosulfonate is a highly electrophilic reagent for methylation. It is ranked as less powerful than methyl trifluoromethanesulfonate.

## Toxicity

Similar to phosgene, it is acutely toxic by inhalation, with an $LC_{50}$ (rat, 1 hour) of about 5 ppm. Several cases of poisoning resulting in death from pulmonary edema have been reported.

