Secondary products from high pressure hydrogenation of crambe oil

Hydrogenation of crambe oil, mainly an α,α’-dierucoyl triglyceride, in the presence of cadmium promoted copper-chromite provides long chain waxes being sought as sperm whale oil replacements. Gas liquid chromatography and gas chromatography-mass spectrometry analyses of secondary products indicate, however, that reduction proceeds rather differently from Adkins-type hydrogenations of triglycerides over copper-chromium oxide catalysts. Monoand diunsaturated alkenes ranging from C₁₆-C₂₄, odd chain lengths included, constitute ca. 1% of the product. Esters of crambe acids with methyl, ethyl, n-propyl, and isopropyl alcohols account for less than 5%. These alcohols and traces of 1,2-propanediol from the hydrogenolysis of glycerol occur in either the head gas or the reaction mixture or both. In contrast to published results for Adkins-type hydrogenations of triglycerides, n-propyl alcohol is far more abundant than isopropyl alcohol or 1,2-propanediol. Isopropyl esters of C-18 acids are not present, and those of C-22 acids constitute no more than 2% of the total esters. Low proportion of isopropyl esters and enrichment of C-22 acids in the secondary products compared with C-18 acids suggest that the acyl substituent at the β-position of glycerol is eliminated during hydrogenation of crambe oil with a Cd−Cu−Cr catalyst. Presented at the AOCS Meeting, Mexico City, April 1974. ARS, USDA.