[′meth·əl ¦klȯrə¦fȯr‚māt] (organic chemistry) ClCOOCH3 A toxic, corrosive, colorless liquid with a boiling point of 71.4°C; soluble in benzene, ether, and methanol; used as a lacrimator in military poison gas and for insecticides. Also known as methyl chlorocarbonate.