|Dailey jr, Oliver|
Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/1/2007
Publication Date: 6/1/2007
Citation: Dailey Jr, O.D., Prevost, N.T. 2007. Conversion of methyloleate to branched-chain derivatives. Journal of the American Oil Chemists' Society. 84:565-571. Interpretive Summary: The use of vegetable oils as alternative diesel fuels (biodiesel) has been investigated for over a century. In the United States, soybean oil has received the most interest. 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 of these biodiesel fuels present a problem in their development and commercialization. Oleic acid and linoleic acid are the most abundant fatty acids of cottonseed oil. As part of a project to develop new value-added industrial applications for cottonseed oil (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 derivatives. The synthesized product exhibited a significantly lower re-crystallization temperature 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 that biodiesel (using methyl oleate as a model compound) can be converted to branched-chain derivatives exhibiting enhanced low-temperature properties.
Technical Abstract: Studies were conducted in the synthetic conversion of oleic acid to mid-chain branched fatty acids. Methyl oleate was brominated in the allylic positions. Reaction of the allylic bromides with lithium dimethylcuprate gave primarily the desired branched-chain derivatives (93% of product mixture). The product had a significantly lower crystallization temperature in comparison with methyl oleate. Reaction of the allylic bromides with lithium di-n-butylcuprate or lithium di-sec-butylcuprate also gave branched-chain derivatives, but in this instance there was the complication of attack on the ester functionality in the fashion of a Grignard reagent. Details of the syntheses and the properties of the products (with emphasis on low-temperature properties) will be discussed.