Two-step free radical catalyzed process for the preparation of alkenyl succinic anhydride

Abstract

A process for the preparation of an alkenyl-substituted succinic anhydride wherein the alkenyl substituent has a number average molecular weight of from about 500 to 5000 and the average number of succinic groups per alkenyl group is greater than 1.2 which comprises: (a) reacting a polyolefin having an alkylvinylidene isomer content of less than about 10 percent and a number average molecular weight of about 500 to 5000 with maleic anhydride in the presence of a free radical initiator at a temperature in the range of about 100.degree. C. to 220.degree. C. to provide a mixture of alkenyl succinic anhydride having an average of greater than 1.2 succinic groups per alkenyl group and unreacted polyolefin, wherein the conversion of polyolefin is from about 30 to about 65 percent, and (b) reacting the mixture of alkenyl succinic anhydride and unreacted polyolefin with maleic anhydride at a temperature in the range of about 200.degree. C. to 250.degree. C. to thereby provide an alkenyl succinic anhydride having an average of greater than 1.2 succinic groups per alkenyl group, wherein the total conversion of polyolefin is about 5 to 40 percentage points higher than the conversion in step (a).

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