Method of preparing monofluoromethyl ethers

摘要

A method for the preparation of a monofluoromethyl ether is described. The monofluoromethyl ether has the formula: wherein A is fluoro C1-6 alkyl, fluorine or chlorine and R1 and R2 are independently selected from the group consisting of hydrogen, C1-6 alkyl, branched C1-6 alkyl, fluoro C1-6 alkyl, fluorine and chlorine with the proviso that at least one of A, R1 or R2 is fluoro C1-6 alkyl, C1-6 alkyl or branched C1-6 alkyl. The method comprises reacting the corresponding monochloromethyl ether with a sterically hindered tertiary amine hydrofluoride salt. The sterically hindered tertiary amine has the formula: in which X, Y, and Z are independently selected from the group consisting of C1-6 alkyl, branched C1-6 alkyl and cyclo C1-6 alkyl, with the proviso that at least one of X, Y and Z consists of a branched C1-6 alkyl or cycloalkyl group. The reaction is carried out using an excess of the monochloromethyl ether starting material relative to the amount of the sterically hindered tertiary amine hydrofluoride salt, in the absence of added solvent.