Process for the preparation of cyclic acid anhydrides

Abstract

Abstract A PROCESS IS DEFINED FOR HEATING AN ORGANIC COMPOUND CONTAINING AT LEAST ONE HALF-ESTER OF A DICARBOXYLIC ACID WHERE THE CARBONYL GROUPS ARE DIRECTLY CONNECTED TO ADJACENT INTERNAL ALIPHATIC CARBON ATOMS TO A TEMPERATURE IN EXCESS OF ABOUT 80*C. TO CONVERT THE HALF-ESTER GROUPS TO CYLIC ANHYDRIDE GROUPS AND A BY-PRODUCT ALCOHOL. THE ORGANIC COMPOUND IS A 1:1 COPOLYMER OF AN ALIPHATIC HYDROCARBON HAVING AT LEAST THREE CARBON ATOMS, SUCH AS 1-HEXENE, AND MALEIC ANHYDRIDE. THE ORGANIC COMPOUND PREPARED FROM AN OLEFIN HAVING FROM THREE TO TEN CARBON ATOMS CAN BE PRECIPITATED AS A SOLIC FROM ITS HOMOGENEOUS REACTION MEDIUM BY POURING THE REACTION SOLUTION INTO A MONOHYDROXY ALCOHOL HAVING ONE TO FOUR CARBON ATOMS, SUCH AS METHANOL. SOME METHYL HALF-ESTER FORMS CAN BE REMOVED BY HEATING THE SEPARATED SOLID PRODUCT AT A TEMPERATURE IN EXCESS OF 80*C. WHILE REMOVING THE MONOHYDROXY ALCOHOL. THUS, 1-HEXENE-MALEIC ANHYDRIDE COPOLYMERS FREE OF HALF-ESTER GROUPS CAN BE RECOVERED. IF THE ORGANIC COMPOUND CONTAINS BOTH HALF-ESTER AND DIESTER GROUPS, THE RESULTING COMPOUND AFTER HEATING TO A TEMPERATURE IN EXCESS OF 80*C. WILL CONTAIN ANHYDRIDE AND DIESTER LINKAGES.

Inventors

• 👤 William J Heilman

Bibliographic Details