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ARS Home » Research » Publications at this Location » Publication #230724
Title: Synthesis and physical properties of isostearic acids and their esters

Author
item Ngo, Helen
item Dunn, Robert - Bob
item SHARMA, BRAJENDRA - VISITING SCIENTIST
item Foglia, Thomas

Submitted to: European Journal of Lipid Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/13/2010
Publication Date: 12/27/2010
Citation: Ngo, H., Dunn, R.O., Sharma, B., Foglia, T. 2010. Synthesis and physical properties of isostearic acids and their esters. European Journal of Lipid Science and Technology. 113:180-188.

Interpretive Summary: Currently, most lubricants and hydraulic fluids used in industry are formulated almost entirely from petroleum-based materials and therefore are for the most part non-biodegradable and environmentally unfriendly. In contrast to petroleum based materials, similar type products generated from renewable materials not only exhibit the required fluidity and oxidative stability but also are nontoxic, environmentally friendly and potentially biodegradable. In particular, the branched-chain fatty acids that can be obtained from common fats and oils are reported to be potential replacements for petroleum-based lubricants and hydraulic fluids in many applications. Our group has recently developed an improved process for producing branched-chain fatty acids from unsaturated linear-chain fatty acids. The branched-chain fatty acids were prepared from unsaturated fatty acids using a novel solid acid catalyst at high temperature and high pressure. Selected physical properties of the branched-chain fatty acids and several of their ester derivatives were measured to assess the potential use of these materials as non-petroleum based lubricants. The results showed that the branched-chain fatty acids indeed were potentially good candidates for lubricant applications.

Technical Abstract: Saturated branched-chain fatty acids (sbc-FAs) are found as minor constituents in several natural fats and oils. Sbc-FAs are of interest since they have lower melting points than their linear counterparts and exhibit good oxidative stability; properties that make them ideally suited in a number of applications. Sbc-FAs were synthesized by clay- or zeolite-catalyzed isomerization of unsaturated linear-chain fatty acids (ulc FAs) to unsaturated branched-chain fatty acids (ubc-FAs), which were subsequently hydrogenated to the desired sbc-FAs. These acid-catalyzed isomerization reactions, however, proceed in moderate conversion and selectivity. Recently, our group found that H-Ferrierite zeolite catalyst isomerized ulc-FAs to their branched-chain counterparts in high conversion (>95%) and selectivity (85%). This paper reports the use of this type of catalyst for the preparation of a series of sbc-FAs and their ester derivatives. Selected physical properties of these branched acids and esters such as cloud and pour points, cold filter plugging point, viscosity index, thermo-oxidation stability, iodine value and lubricity also are reported.