Process for the preparation of 3,5-bis(trifluoro-methyl)-benzoyl chlorides and novel 3,5-bis(tri-halogenomethyl)-and 3,5-dimethylbenzoyl halides

摘要

3,5-Bis(trifluoromethyl)benzoyl chlorides optionally substituted with fluorine or chlorine are advantageously prepared by converting 3,5-dimethylbenzoic acids optionally substituted with fluorine or chlorine into the corresponding acid chlorides; completely free-radically chlorinating said chlorides in the side chains, giving 3,5-bis(trichloromethyl)benzoyl chlorides optionally substituted by fluorine or chlorine; fluorinating the latter with anhydrous hydrogen fluoride and/or antimony pentafluoride, giving 3,5-bis(trifluoromethyl)benzoyl fluorides optionally substituted with fluorine or chlorine; and then reacting the 3,5-bis(trifluoromethyl)benzoyl fluorides with silicon tetrachloride in the presence of a further Lewis acid. Some of the 3,5-bis(trihalogenomethyl) and 3,5-dimethylbenzoyl halides which arise as intermediates are novel compounds.