Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/10/2009
Publication Date: 8/7/2009
Citation: Dailey Jr, O.D., Prevost, N.T., Strahan, G.D. 2009. Conversion of methyl oleate to branched-chain hydroxy fatty acid derivatives. Journal of the American Oil Chemists' Society. 86:1101-1114.
Interpretive Summary: The use of vegetable oils as alternative diesel fuels (biodiesel) has been investigated for over a century. Biodiesel is presently typically obtained by the conversion of vegetable oils or animal fat to simple esters of fatty acids. These products, usually methyl or ethyl esters, can be utilized as alternative fuels or extenders in diesel engines. However, the relatively poor low-temperature properties (freezing in cold climates) of these biodiesel fuels present a problem in their development and commercialization. Oleic acid and linoleic acid are the most abundant fatty acids of many vegetable oils, including cottonseed oil. As part of a project to develop new and expanded uses of cottonseed and other oilseed products and by-products (such as biodiesel, fuel additives, and lubricants), studies were conducted in the synthetic conversion of oleic acid to branched-chain fatty acids. Esters of branched-chain fatty acids should have improved or superior low-temperature properties. In these studies, methyl oleate (a major component of biodiesel) was converted in a series of reactions to branched-chain hydroxy acid derivatives. The products were purified and their structures were unequivocally determined. Several of the products exhibited significantly lower re-crystallization temperatures in comparison with methyl oleate. This research benefits farmers of cotton and other oilseed crops, oil chemists, and the automotive industry in that it demonstrates certain branched-chain hydroxy fatty acid derivatives could have improved or superior low-temperature properties and may prove useful as additives to biodiesel for use at low temperatures.
Technical Abstract: As part of a project to develop new and expanded uses of oilseed products and by-products (such as biodiesel, fuel additives, and lubricants), studies were conducted on the synthetic conversion of oleic acid (in ester form) to branched-chain fatty acid ester derivatives. In these studies, methyl oleate was epoxidized and subsequently treated with four different organocuprate reagents in the presence of boron trifluoride diethyl etherate to produce novel branched-chain hydroxy acid derivatives. For each reaction, the two distinct isomeric products (methyl 9-alkyl-10-hydroxyoctadecanoate and methyl 9-hydroxy-10-alkyloctadecanoate) were isolated in pure form. Details of the syntheses and characterization (GC/MS, NMR, and DSC) of these compounds will be discussed.