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Characterization of estolides produced from the acid-catalyzed condensation of oleic acid
- Isbell, T.A., Kleiman, R.
- Journal of the American Oil Chemists' Society 1994 v.71 no.4 pp. 379
- oleic acid, fatty acid esters, hydrolysis, chemical analysis, gas chromatography, nuclear magnetic resonance spectroscopy, mass spectrometry, titration, high performance liquid chromatography
- Estolides produced from an acid-catalyzed condensation of oleic acid were characterized by high-performance liquid chromatography (HPLC), gas chromatography (GC), GC-mass spectrometry (MS) and nuclear magnetic resonance (NMR). C-8 reverse-phase HPLC provided a clean resolution of the estolide oligomers present in the reaction mixtures, allowing an average oligomier distribution to be calculated. Corroboration of HPLC results were obtained either through hydrolysis of the estolide mixture and quantitation of the hydroxy fatty acid content by GC, through the integration of the α-methylene protons adjacent to the carbonyl of the acids vs. the esterns in the1H NMR spectrum, or by titration of the carboxylic acid with standardized base. GC and GC-MS analysis of the hydrolyzed estolide mixture indicated that the ester position were centered around the original double-bond position, with linkages ranging from positions 5-13. Likewise, the unsaturation was distributed along the fatty acid backbone.