Dibasic acid treating process

Claim 1

A PROCESS FOR THE SEPARATION OF SUCCINIC ACID FROM A MIXTURE OF SUCCINIC ACID WITH AT LEAST ONE DIBASIC ACID OF THE FORMULA HOOC(CH2)NCOOH WHERE N IS AN INTEGER HAVING A VALUE OF AT LEAST 3 WHICH COMPRISES: FORMING A DISTILLAND OF SAID MIXTURE AND AN INERT HYDROPHOBIC ORGANIC SOLVENT, SAID SOLVENT HAVING AN ATMOSPHERIC BOILING POINT OF BETWEEN 175 AND 220*C. AND BEING CAPABLE OF DISSOLVING AT LEAST ABOUT 5 GRAMS OF SUCCINYL MATERIAL SELECTED FROM THE GROUP CONSISTING OF SUCCINIC ACID AND SUCCINIC ANHYDRIDE AND MIXTURES THEREOF PER 100 GRAMS OF THE SOLVENT AT A TEMPERATURE OF 175-220*C., SUBSTANTIALLY EXHAUSTING SAID DISTILLAND OF SUCCINIC ACID BY HEATING SAID DISTILLAND TO A TEMPERATURE OF BETWEEN 175 AND 220* C., CONDENSING THE RESULTING VAPOR TO FORM A CONDENSATE COMPRISING SUCCINIC ANHYDRIDE, SUCCINIC ACID, WATER AND SOLVENT, COOLING SAID CONDENSATE TO A TEMPERATURE BETWEEN ABOUT 60 AND 150*F., SEPARATING THE RESULTANT SOLID PHASE SUCCINIC ANHYDRIDE AND SUCCINIC ACID FROM THE CONDENSED SOLVENT AND RETURNING THE CONDENSED SOLVENT TO SAID DISTILLAND, SUBSEQUENTLY CRYSTALLIZING OUT AND SEPARATING DIBASIC ACIDS REMAINING IN THE DISTILLATION RESIDUE, THEN LIXIVIATING THE SEPARATED DIBASIC ACIDS WITH LIQUID PHASE SULFUR DIOXIDE AND THEREAFTER SEPARATING THE RESULTANT LIXIVIUM FROM AN INSOLUBLE PURIFIED DIBASIC ACID FRACTION.