Process for the preparation of halogenated benzoic acid

Process for the preparation of 3-chloro-2-fluoro-5-trifluoromethyl-benzoic acid of formula: ** ** Formula or a salt thereof, comprising the conversion of 3-chloro-4-fluorobenzotrifluoride of formula: * * ** Formula by a1) deprotonation of 3-chloro-4-fluorobenzotrifluoride with a metalorganic base followed by addition deco2 as electrophile in an organic solvent at a reaction temperature of between -100 and 25 ° C, or b1) forming a Grignard compound of 3-chloro-4-fluorobenzotrifluoride with an alkyl halide alquilmagnesioen an organic solvent at a reaction temperature of between 20 and 100, followed by addition of electrophile CO2como in an organic solvent at a temperature of between -100 and 25 ° C or by: a2) conversion of 3-chloro-4-fluorobenzotrifluoride of formula II in 3-chloro-2-fluoro-5-trifluoromethylbenzaldehyde of the formula: ** ** formula