Positional analysis of isovaleroyl triglycerides using proton magnetic resonance with Eu (fod) 3 and Pr (fod) 3 shift reagents: I. Model compounds.

The proton magnetic resonance spectra of isomeric triglycerides of isovaleric and palmitic acids in the presence of the downfield and upfield chemical shift reagents Eu(fod)(3) and Pr(fod)(3) were studied. The resonance profiles of the gamma-protons on the isovaleroyl chains are distinctive for each of the four possible triglyceride isomers at low shift reagent/triglyceride ratios. With either reagent, the well defined gamma-methyl isovalerate doublets can be used to identify 2-isovaleroyl and 1,3-isovaleroyl structures and to analyze isomeric mixtures. This technique will be useful for positional analysis of natural cetacean triglycerides containing isovaleric acid.