THE RHODIUM-CATALYZED DEUTERATION OF UNSATURATED TRIGLYCERIDES

Tripalmitolein, triolein, trilinolein and trilinolenin were deuterated with deuterium gas and Wilkinson’s catalyst [(Ph3P)3RhCl(I)]. Recrystallization of the products from acetone yielded highly pure deuterium-labelled triglycerides (TG). The deuterated TG were converted to methyl esters and analyzed by gas chromatography/mass spectroscopy to determine the deuterium distribution. Methyl palmitate-9,10-d2 (from tripalmitolein) and methyl stearate-9,10-d2 (from triolein) yielded isotopic distributions of 93–97% d2, methyl stearate-9,10,12,13-d4 (from trilinolein) of 74% d4 and methyl stearate-9,10,12,13,15,16-d6 (from trilinolenin) of only 58% d6. Because the deuterium-labelled TG were to be used in human metabolism studies, atomic absorption spectroscopy was used to determine if any residual rhodium was present. No rhodium was detected at 70 ppb (the minimum detection limit). © 1990, The American Oil Chemists’ Society. All rights reserved.