In organic chemistry, a methoxymethyl ether is a functional group with the formula ROCH2OCH3, abbreviated MOM. It is a kind of chloroalkyl ether and, like its congeners, often employed in organic synthesis to protect alcohols. They are usually derived from 2-methoxymethyl chloride.[1][2] Closely related to MOM ethers are methoxyethoxymethoxy (MEM) protecting groups, introduced using 2-methoxyethoxymethyl chloride. The MEM protecting groups are more easily installed and more easily removed.