A convenient synthesis of chloromethyl methyl ether in situ involves the reaction of dimethoxymethane and acetyl chloride in the presence of a Lewis acid catalyst  This route affords a methyl acetate solution of chloromethyl methyl ether of high purity.  A similar method, using a high-boiling acyl chloride, can be used to prepare pure, dimethoxymethane being the only contaminant.  In contrast, the classical procedure reported in Organic Syntheses employing formaldehyde, methanol, and hydrogen chloride yields material significantly contaminated with the dangerous bis(chloromethyl) ether and requires fractional distillation.