Catalytic carboxylation of fats: Carboxy acids from polyunsaturates

Studies with a palladium chloride‐triphenylphosphine catalyst have been extended to the carboxylation of polyunsaturated fats. Linseed, soybean, and safflower oils, acids, and esters were carboxylated catalytically with water‐carbon monoxide (4000 psig) at 120–160 C with or without acetone as a solvent. Main products were monocarboxy, 1,3‐ and 1,4‐dicarboxy and tricarboxy acids. Minor products were carbomethoxy esters and disubstituted 2‐cyclopentenone. Optimum reaction conditions were determined for the carboxylation of linseed oil and methyl esters by statistically designed experiments. Yields of total carboxy and tricarboxy acids were maximized at low triphenylphosphine and water levels, low temperatures, and high palladium‐chloride concentrations. Carboxylated soybean esters were separated by ether extraction of the palladium catalyst from sodium carbonate or hydroxide carboxylate salts. This salt extraction permits catalyst recycling.