Patent ID: 6355835
Filing Date: 2002-03-12
Classification: C07C

Abstract:
A process for the preparation of benzene-dicarboxylic acid by liquid phase oxidation of xylene isomer comprising:oxidizing a xylene isomer with air or oxygen in an autoclave at a pressure of 5-80 kg/cm2 and temperature ranging between 100-150Â° C. in the presence of an acetic acid solvent, a cobalt salt catalyst in the ratio of 5.0 to 25 mole percent of said xylene feed and an initiator in proportions of 0.05 to 1 mole per mole of the said catalyst, for a period of 1 to 6 hours to form a reaction mixture; flashing the said reaction mixture to remove volatile substances, followed by cooling to 20-40 C.Â° and filtering/centrifuging to get crude benzene dicarboxylic acid as solid product and filtrate; recrystallizing the said crude benzene dicarboxylic acid to get at least 99% pure benzene dicarboxylic acid; in the presence of a solvent selected from methanol, ethanol, water or acetic acid.