Vinyl ketostearates. Preparation, properties, infrared spectra, and analysis of 4‐ and 12‐ketostearates

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Abstract
Summary: Vinyl 12‐ketostearate and vinyl 4‐ketostearate were prepared by vinylating 12‐ketostearic and 4‐ketostearic acids, respectively, with vinyl acetate in the presence of a mercuric sulfate catalyst. The crude vinyl esters were purified by extracting the free fatty acids with dilute potassium carbonate, removing the mercury by distillation, and crystallizing successively from acetone and pertroleum ether.Infrared analyses revealed that lactonization occurred with the 4‐ketostearic acid during the hydrogenation of the oiticica oil and during the vinylation of the keto acid. Two γ‐lactones were produced. The γ‐lactone of 4‐hydroxy‐2‐octadecenoic acid was isolated in relatively pure form, and evidence was obtained for the concurrent formation of the less stable γ‐lactone of 4‐hydroxy‐3‐octadecenoic acid. The infrared spectra of the methyl keto esters, keto acids, vinyl keto esters, and the γ‐lactone of 4‐hydroxy‐2‐octadecenoic acid were determined in carbon tetrachloride solutions. It was found that the characteristic absorbances for the lactone‐carbonyl, ester‐carbonyl, ketonecarbonyl, and the vinyl group at about 5.6, 5.7, 5.8, and 6.1 microns, respectively, obey the Lambert‐Beer law over a wide range of concentrations.