Process for the production of aromatic di-and polycarboxylic acids

Claim 1

IN A PROCESS FOR THE PRODUCTION OF AROMATIC POLYCARBOXYLIC ACIDS BY HEATING, AS STARTING MATERIALS, ALKALI METAL SALTS OF AROMATIC MONOCARBOXYLIC ACIDS HAVING THE SAME RING STRUCTURE AS THE ACID TO BE PRODUCED, IN AN ATMOSPHERE OF CARBON DIOXIDE, UNDER SUBSTANTIALLY ANHYDROUS CONDITIONS, TO A TEMPERATURE FROM BETWEEN ABOUT 350*C. TO A TEMPERATURE BELOW THE DECOMPOSITION TEMPERATURE OF THE STARTING MATERIALS AND PRODUCTS IN THE PRESENCE OF AN ACID BINDING AGENT, WHEREBY THE STARTING SALTS ARE CONVERTED INTO THE CORRESPONDING SALTS OF THE ACID TO BE PREPARED, AND THEREAFTER SEPARATING THE FREE ACID TO BE PREPARED, AND THEREAFTER SEPARATING THE FREE CATION, THE IMPROVEMENT OF HEATING SAID STARTING SALTS IN THE PRESENCE OF A WATER-BINDING AGENT CAPABLE OF REACTING WITH THE WATER FORMED DURING THE REACTION IN SUFFICIENT QUANTITY TO BIND ONE-HALF MOL OF WATER FOR EACH MOL OF ALKALI METAL CARBOXYLATE.