Preparation of 3-bromo-4-fluorobenzaldehyde and its acetals

摘要

A process for the preparation of a 3-bromo-4-fluorobenzaldehyde acetal of the formula <IMAGE> in which R1 is methyl or ethyl, which comprises reacting a 3-bromo-4-fluoro-benzoic acid halide with ammonia to form 3-bromo-4-fluoro-benzoic acid amide, dehydrating said amide to form 3-bromo-4-fluoro-benzonitrile, reacting the nitrile with formic acid in the presence of a catalyst at a temperature between about 0 DEG and 150 DEG C. to form 3-bromo-4-fluorobenzaldehyde, and reacting said aldehyde with R1OH or a derivative thereof capable of forming an acetal. The amide and nitrile are new compounds. The acetals are known intermediates in the synthesis of pyrethroid-like insecticides.