Method for oxidation of xylene derivatives

This invention relates to a method for oxidizing xylene derivatives. More particularly, the invention relates to a method for oxidizing a substrate comprising at least one halo-ortho-xylene in the presence of at least one metal catalyst, at least one solvent, and at least one promoter to provide a product comprising halo-phthalic acid or halo-phthalic anhydride. In one key embodiment the invention relates to a method for producing a product comprising 4-chlorophthalic acid or 4-chlorophthalic anhydride. Xylene derivatives, such as chloro-ortho-xylene, are oxidized in a solvent in the presence of at least one metal catalyst with addition of promoter after the reaction has proceeded to an intermediate stage of conversion to product mixture. The product comprises chlorophthalic acid or chlorophthalic anhydride.