Methyl chloroformate is the methyl ester of chloroformic acid

Chloroformic acid

Chloroformic acid is an unstable chemical compound with the formula ClCO2H. It is the single acyl-halide derivative of carbonic acid . Chloroformic acid is also structurally related to formic acid, which has a hydrogen instead of the chlorine...

. It is also known as methyl chlorocarbonate, and is an oily liquid with a colour that is anywhere from yellow to colorless. It is also known for its pungent odour. Methyl chloroformate, if heated, releases phosgene

Phosgene

Phosgene is the chemical compound with the formula COCl2. This colorless gas gained infamy as a chemical weapon during World War I. It is also a valued industrial reagent and building block in synthesis of pharmaceuticals and other organic compounds. In low concentrations, its odor resembles...

 and produces toxic, corrosive fumes if it comes in contact with water.

Methyl chloroformate is used in organic synthesis

Organic synthesis

Organic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic molecules can often contain a higher level of complexity compared to purely inorganic compounds, so the synthesis of organic compounds has...

 for the introduction of the methyl ester functionality to a suitable nucleophile

Nucleophile

A nucleophile is a species that donates an electron-pair to an electrophile to form a chemical bond in a reaction. All molecules or ions with a free pair of electrons can act as nucleophiles. Because nucleophiles donate electrons, they are by definition Lewis bases.Nucleophilic describes the...

.