CN200580049288: Process for the preparation of p-toluic acid by liquid phase oxidation of p-xylene in water

The invention provides a process for the preparation of p-toluic acid by liquid phase oxidation of p-xylene using oxygen or air as oxidant in the presence of p-toluic acid, water as solvent and cobalt salt or its combinations with salts of Ce, Mn as catalyst. Oxidation is carried out at 130-1900 C and pressure sufficient to keep water in liquid state. Oxidation step is followed by filtration to obtain p-toluic acid as major product. Untreated p-xylene is recovered and recycled and the catalyst is recovered from aqueous phase and is recycled.