Catalytic autoxidation of 9(10)‐formylstearic acid

A procedure has been developed for the preparation of carboxystearic acid by catalytic autoxidation of hydroformylated oleic acid. This autoxidation is catalyzed effectively with Ca, Cu, Co, Fe, Mn and Ce naphthenates in either acetone or glacial acetic acid at 20 C. With the exception of Ca, all these catalysts produce from 2 to 10% keto‐ and hydroxystearic acids as by products. Yields of up to 95% 9(10)‐carboxystearic acid are obtained by autoxidation for 24 hr with Ca naphthenate (0.5% Ca based on formylstearate). This autoxidation period was shortened to 7 hr by using a binary catalyst (0.5% Ca and 0.05% Mn), which affords a minimum of side products.