The aromatization of linoleic acid with palladium catalyst

Abstract

Summary Hydrogen transfer catalysts are known to promote the elaidinization and conjugation of unsaturated fatty acid derivatives. More extensive reactions were indicated when palladium was tried as a polymerization catalyst. A subsequent study showed that methyl linoleate could be readily cyclized and aromatized in the presence of palladium. Methyl linoleate was heated in an evacuated ampule for 6 hrs. at 270°C. with 5% of a 10% palladium on charcoal. The iodine value was lowered to 43.9 and the apparent linoleate content to less than 2%. The products were separated by urea segregation and distillation. They consisted of approximately 7% polymer, 18% methyl stearate, 40% monoolefins, and 30% of a methyl ester of an aromatic fatty acid (handling loss 5%). The aromatic material was readily oxidized to orthophthalic acid. The mechanism by which aromatics, mono‐olefins, and saturates are produced through cyclization and hydrogen transfer is not known, but possible routes are suggested.

Copper catalysts in the selective hydrogenation of soybean and rapeseed oils: III. The effect of pressure when using copper chromite catalyst

“…Due to a low degree of hydrogen dissociation, hydrogen atoms temporarily bonded to the catalyst surface as a result of the adsorption of fatty molecules are added to other fatty molecules, which are hydrogenated. Such a hydrogen transfer was observed by Floyd et al (14) on heating linolenic acid and its methyl esters in the presence of palladium. The donor molecules are hydrogenated in a consecutive step.…”

Reactions of the Hydrocarbon Chain of Fatty Acids.

“…Methyl linoleate when heated for 6 hr. at 270°with palladium on charcoal yielded a mixture which was estimated to contain 30 per cent aromatic compounds, 40 per cent monoólefins, 18 per cent stearate, and 7 per cent polymer (170). Further fractionation of the aromatic portion and oxidation of one of the fractions yielded phthalic acid (identified as the anhydride).…”