Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/6/2007
Publication Date: 5/30/2007
Citation: Moser, B.R., Sharma, B.K., Doll, K.M., Erhan, S.Z. 2007. Diesters from oleic acid: synthesis, low temperature properties, and oxidation stability. Journal of the American Oil Chemists' Society. 84:675-680. Interpretive Summary: A series of organic compounds has been prepared from the readily available vegetable oil based material, oleic acid. We have studied these materials with respect to their low temperature behavior and oxidation stability. These are important properties for the development of additives for the lubricant and biodiesel industries. The organic compounds evaluated in this study exhibit improved low temperature performance and oxidation stability when compared to soybean oil. This research benefits the vegetable oil industry by helping to open markets for vegetable oil-based materials for use in lubricant and fuel applications.
Technical Abstract: Several diesters were prepared from commercially available oleic acid and common organic acids. The key step in the three step synthesis of oleochemical diesters entails a ring opening esterification of alkyl 9,10-epoxyoctadecanoates (alkyl: propyl, iso-propyl, octyl, 2-ethylhexyl) using propionic and octanoic acids without the need for either solvent or catalyst. Each synthetic diester was evaluated for both cold flow behavior and oxidation stability through measurement of cloud point, pour point, oxidation onset temperature, and signal maximum temperature. It was discovered that increasing chain length of the ester side chain and branching in the ester head group has a positive influence on the low temperature properties of diesters. Improved oxidation stability is achieved when the chain length of the ester side chain is decreased. Additionally, the ester side chain plays a larger role in oxidation stability than the ester head group, which may be due to the secondary versus primary nature of the ester linkages. These products may prove useful in the search for bio-based industrial materials, such as lubricants, surfactants, and fuel additives.