Chloromethyl methyl ether (CMME) is a compound with formula CHOCHCl.  A colorless liquid, it is a chloroalkyl ether.  It is used as an alkylating agent. In organic synthesis, it is used for introducing the methoxymethyl ether (MOM) 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.