Chloromethyl methyl ether is a compound with formula CH3OCH2Cl. It is a chloroalkyl ether. It is used as an alkylating agent and industrial solvent to manufacture the detergent dodecylbenzyl chloride, water repellents and ion-exchange resins. In organic synthesis, it is used for introducing the methoxymethyl protecting group, and is thus often called MOM-Cl or MOM chloride. It also finds application as a chloromethylating agent in some variants of the Blanc chloromethylation. A convenient and reliable method to prepare chloromethyl methyl ether in situ is by combining dimethoxymethane and acetyl chloride, either neat or as a solution in an inert solvent like toluene, in the presence of zinc bromide as a catalytic Lewis acid. This mixture affords a solution of chloromethyl methyl ether of high purity in methyl acetate which can be used directly in many applications. A very similar method, using a high-boiling acyl chloride, can be used to prepare pure material. After simple distillation, this method yields >93% pure material with dimethoxymethane as the only contaminant. In contrast, the classical procedure reported in Organic Syntheses employing formaldehyde, methanol and hydrogen chloride yields material contaminated with a significant amount of the dangerous bis ether and requires fractional distillation. The amount of time required to destroy residual chloromethyl methyl ether using various standard aqueous quench solutions has been measured. In all cases, a solution of chloromethyl methyl ether in toluene/methyl acetate was destroyed after vigorous stirring with the quench solution for 15 minutes. CMME is a known human carcinogen. Chronic exposure can increase the incidence of respiratory cancers, including small cell carcinoma. It is one of 13 chemicals regulated by the Occupational Safety and Health Administration despite not having an established permissible exposure limit. It is classified as an extremely hazardous substance in the United States as defined in Section 302 of the U.S. Emergency Planning and Community Right-to-Know Act, and is subject to strict reporting requirements by facilities which produce, store, or use it in significant quantities. It listed in Schedule 1 Part 1 of Canada's Prohibition of Certain Toxic Substances Regulations.
