Methyl chloroformate

Not to be confused with Methyl chloroform.

Methyl chloroformate is a chemical compound with the chemical formula Cl−C(=O)−O−CH₃. It is the methyl ester of chloroformic acid. It is an oily colorless liquid, although aged samples appear yellow. It is also known for its pungent odor.

Methyl chloroformate^[1]

Names
Preferred IUPAC name Methyl carbonochloridate
Other names Methyl chloroformate, Chlorocarbonic methyl ester, Methyl chlorocarbonate
Identifiers
CAS Number	79-22-1 Y
3D model (JSmol)	Interactive image Interactive image
Beilstein Reference	605437
ChemSpider	6337 Y
ECHA InfoCard	100.001.080
EC Number	201-187-3
PubChem CID	6586
UNII	RC6VA8OB2N Y
CompTox Dashboard (EPA)	DTXSID0024185
InChI InChI=1S/C2H3ClO2/c1-5-2(3)4/h1H3 Y Key: XMJHPCRAQCTCFT-UHFFFAOYSA-N Y InChI=1/C2H3ClO2/c1-5-2(3)4/h1H3 Key: XMJHPCRAQCTCFT-UHFFFAOYAT
SMILES O=C(Cl)OC ClC(=O)OC
Properties
Chemical formula	ClC(O)OCH3
Molar mass	94.49 g·mol−1
Appearance	Colorless oily liquid
Odor	Pungent
Density	1.223 g/mL
Boiling point	70 to 72 °C (158 to 162 °F; 343 to 345 K)
Hazards
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H225, H302, H312, H314, H330
Precautionary statements	P210, P233, P240, P241, P242, P243, P260, P264, P270, P271, P280, P284, P301+P312, P301+P330+P331, P302+P352, P303+P361+P353, P304+P340, P305+P351+P338, P310, P312, P320, P321, P322, P330, P363, P370+P378, P403+P233, P403+P235, P405, P501
Flash point	10 °C (50 °F; 283 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

Preparation

Methyl chloroformate can be synthesized using anhydrous methanol and phosgene.^[2]

COCl₂ + CH₃OH → ClC(O)OCH₃ + HCl

Properties

Methyl chloroformate hydrolyzes in water to form methanol, hydrochloric acid, and carbon dioxide.^[3] This decomposition happens violently in the presence of steam, causing foaming. The compound decomposes in heat, which can liberate hydrogen chloride, phosgene, chlorine, or other toxic gases.^[4]

Uses

Methyl chloroformate is used in organic synthesis for the introduction of the methoxycarbonyl functionality to a suitable nucleophile (i.e. carbomethoxylation).^[5]

Safety

Methyl chloroformate forms highly flammable vapour-air mixtures. The compound has a flash point of 10 °C.^[6] Methyl chloroformate, if heated, releases phosgene. It produces hydrogen chloride upon contact with water. It will cause skin damage if in contact with skin.

See also

• Ethyl chloroacetate
• Chloroacetic acid