Thionyl Chloride → 3-Chloro-2,4,5-trifluorobenzoyl chloride

Participants

Reaction Steps

The benzoyl halides (1) used as starting materials for this synthetic route are prepared as follows: 3,5-dichloro-2,4-difluorobenzoyl fluoride (boiling point 97° /20 mbar; nD20 =1.5148) and 5-chloro-2,3,4-trifluorobenzoyl fluoride (boiling point 68°-70° /20 mbar; nD20 = 1.4764) are obtained together by heating tetrachlorobenzoyl chloride with potassium fluoride in sulpholane at elevated temperatures: ##STR14## The chlorination of 2,4,5-trifluorobenzoic acid in chlorosulphonic acid leads to 3-chloro-2,4,5-trifluorobenzoic acid which is reacted as the crude product with thionyl chloride to give 3-chloro-2,4,5-trifluorobenzoyl chloride (boiling point 94°/18 mbar; nD20 =1.5164): ##STR15##

Provenance & Evidence