METHOD OF PREPARING AMMONIUM TEREPHTHALATE BY ISOMERIZATION, OR DISPROPORTIONATION OF POTASSIUM SALTS DERIVED FROM BENZENE-CARBOXYLIC ACIDS

Multiple-stage process of isomerizing, or disproportionating potassium salts derived from benzene-carboxylic acids, and ultimate processing of the reaction product containing more than 40 per cent by weight of the terephthalic component, to obtain ammonium terephthalate, wherein the raw reaction product is extracted by a filtrate left after refining precipitation of ammonium terephthalate by ammonia and carbon dioxide, which filtrate contains free ammonium ions and free ammonia. The thus arisen solid phase containing di-ammonium terephthalate is then separated from the reaction mixture, dissolved in water, the thus arisen solution being used, after separation of an insoluble residue, for the preparation of pure di-ammonium terephthalate.