What is "dimethyl sulfate"

alt. (context organic compound English) The methyl ester of sulfuric acid, (CH₃)₂SO₄, used as a methylating agent in organic chemistry n. (context organic compound English) The methyl ester of sulfuric acid, (CH₃)₂SO₄, used as a methylating agent in organic chemistry

Dimethyl sulfate is a chemical compound with formula (CHO)SO. As the diester of methanol and sulfuric acid, its formula is often written as ( CH) SO or even MeSO, where CH or Me is methyl. MeSO is mainly used as a methylating agent in organic synthesis.

Under standard conditions, MeSO is a colourless oily liquid with a slight onion-like odour (although smelling it would represent significant exposure). Like all strong alkylating agents, MeSO is extremely toxic. Its use as a laboratory reagent has been superseded to some extent by methyl triflate, CFSOCH, the methyl ester of trifluoromethanesulfonic acid.