Heats of hydrogenation of large molecules. Part 3.—Five simple unsaturated triglycerides (triacylglycerols)

Abstract

We have determined the enthalpies of hydrogenation of the simple triglycerides of oleic, elaidic, petroselinic, linoleic and linolenic acids. These compounds include the largest molecules ever studied by hydrogen calorimetry and one of them (trilinolenin) produces the largest heat of hydrogenation yet observed. Heats of hydrogenation per double bond for the five triglycerides reported here are remarkably consistent with each other and with those of the free fatty acids and methyl esters previously studied. These results suggest a molecular conformation in hexane solution in which the unsaturated acid residues are well separated and the double bonds are thermochemically independent.