The reaction of beta‐propiolactone with alpha‐and beta‐eleostearates and plasticizer properties of derived esters

Summary Beta‐propiolactone has been employed as the dienophile component in the Diels‐Alder reaction withalpha‐ andbeta‐eleostearates, yielding acrylic acid adducts. Catalytic amounts of potassium carbonate were used to induce polymerization ofbeta‐propiolac‐tone to a polyester and to assist in its pyrolysis to acrylic acid. The ethyl andn‐butyl esters of the mixed fatty acids ofalpha‐and ofbeta‐tung oil, containing about 75% eleostearates, were reacted with the theoretical amount ofbeta‐propiolactone at 200°C. for a period of 1.5 hrs. Spectral analyses indicated nearly quantitative conversion of the reactants to the expected Diels‐Alder products. The acrylic acid adducts were esterified in their reaction mixtures with the appropriate alcohols to produce the corresponding di‐esters. These esters were purified by means of high vacuum distillation. Fractional crystallization of the free acids obtained by saponification of the di‐butyl esters of thealpha‐eleostearic acid adducts yielded two isomeric dicarboxylic acids, melting at 113°C. and 85°C. These isomers differ only in the position of the carboxyl group on the cyclohexene nucleus of the adduct. The di‐ethyl and di‐butyl esters of both thealpha‐andbeta‐eleostearic acid adducts and their hydrogenated derivatives have been intercompared as primary plasticizers for vinyl type resins. The hydrogenated di‐esters of thebeta‐eleostearic acid adducts were found to be the most effective.