4,5-Difluorophthalic Anhydride → 3,4-Difluorobenzoic acid

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According to the present invention, 4,5-difluoroanthranilic acid may be prepared from either 4,5 difluorophthalic anhydride or 4,5-difluorophthalic acid. The process of this invention comprises the decarboxylation of either 4,5-difluorophthalic anhydride and 4,5-difluorophthalic acid in N-methyl-2-pyrrolidone, quinoline, or dimethyl acetamide solution optionally using copper, copper oxide, copper salts, or halides and salts of Zn, Cd, Ag and Ni as a catalyst, to yield 3,4-difluorobenzoic acid; the nitration of the 3,4-difluorobenzoic acid in a mixture of nitric and sulfuric acids to form 2-nitro-4,5-difluorobenzoic acid; and the reduction of the 2-nitro-4,5-difluorobenzoic acid to form 4,5-difluoroanthranilic acid.

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