An Efficient Synthesis of 2,4-Difluoro-3,5-Dichlorobenzoic Acid

2,4-Difluoro-3,5-dichlorobenzoic acid, as a key intermediate for preparing quinolone-3-carboxylic acids, was synthesised from the commercially available 2,4-difluoro-3-chlorobenzoic acid in excellent yield by a reaction sequence involving nitration, selective reduction, diazotisation and chlorination.