Unsaturated Fatty Methyl Esters Research Articles

13C nuclear magnetic resonance of mono‐and dihydroxy saturated and unsaturated fatty methyl esters

Abstract13C nuclear magnetic resonance spectra were obtained for methyl esters oferythro‐ andthreo‐9,10‐dihydroxystearates, for 12‐hydroxy‐cis‐ andtrans‐9‐octadecenoates, and forthreo‐12,13‐dihydroxy‐cis‐andtrans‐9‐octadecenoates.Erythro andthreo compounds may be distinguished easily by the difference in the chemical shifts of the carbons alpha to the hydroxy‐bearing carbons. Monohydroxy compounds are easily distinguished fromvicinal dihydroxy compounds by differences in chemical shifts of both the hydroxy‐bearing carbons and of the carbons alpha to them. The presence of a hydroxy‐bearing carbon beta to a double bond results in the two carbons of the double bond of a hydroxy‐bearing carbon beta to a double bond results in the two carbons of the double bond having different chemical shifts, with the numerical values being different for thecis andtrans isomers. The chemical shift of a carbon alpha to both a doubly bonded carbon and a hydroxy‐bearing carbon is influenced both by the geometry of the double bond and the number of hydroxy‐bearing carbons.