Acyl Esters from Oxo-Derived Hydroxymethylstearates as Plasticizers for Polyvinyl Chloride

Hydroxymethylstearates were made by hydroformylation or oxo reaction of monoand polyunsaturated fats and esters with either rhodium-triphenylphosphine or cobalt carbonyl catalysts. Rhodium-oxo products were hydrogenated with nickel catalyst, whereas, cobalt-oxo products were heated directly under hydrogen pressure. Hydroxymethyl fatty alcohols also were prepared by a two-step copper-cmomite hydrogenation of hydroformylated linseed fatty esters. Of these hydroxymethyl compounds, 39 were converted to their acetates and other acyloxy derivatives and then evaluated as primary plasticizers for polyvinylchloride. For compounds with good compatibility, methyl 9(l0)-acetoxymethylstearate and 9( 10)-acetoxymethyloctadecyl acetate gave the lowest flex temperature (-47 C). An unusual combination of good compatibility and low flex temperature was obtained with 2-methoxyethyl 9( 10)-acetoxymethylstearate. Addition of more than one acetoxymethyl group in the fatty acid molecule, made possible by rhodium hydroformylation, imparted good compatibility and outstanding permanence (low migration and volatility) but raised flex temperature. Butyl diacetoxymethylstearate, methyl triacetoxymethylstearate, and polyacetoxymethyloctadecyl acetate from linseed esters displayed good compatibility, strength, and volatility characteristics. As glycerides, acetoxymethylated safflower and linseed oils produced good compatibility and outstanding permanence, better than esters commonly used as commercial plasticizers.