Describes a method for obtaining substantially pure chloromethyl chloroformate
from a chloroformate mixture comprising chloromethyl chloroformate and methyl chloroformate
by heating the chloroformate mixture in a reaction zone at temperatures ranging
from at least 50 C. to the reflux temperature of the chloroformate mixture
in the reaction zone while simultaneously removing volatile gaseous decomposition
products from the reaction zone. Dichloromethyl chloroformate may also be present
in the chloroformate mixture.