Characterization of monomers produced from thermal high‐pressure conversion of meadowfoam and oleic acids into estolides

Abstract

The monomers produced from thermal high‐pressure conversion of meadowfoam or oleic acids into estolides were characterized as a complex mixture of fatty acids. Mild reaction conditions produced little change in the starting acids. However, vigorous reaction conditions,e.g. ≥3 h at 250°C with stirring, significantly altered the starting fatty acids.Cis/trans isomerization occurred readily, with the proportion oftrans isomers reaching 57%. In addition, the double bonds migrated throughout all positions of the hydrocarbon chain with concentrations diminishing outward from the starting double bond position. Branching was also observed to a small extent under these conditions and was even more pronounced in the absence of water. Lactones were also identified in the reaction mixture, with contents near 16% in the meadowfoam series. All products can be explainedvia carbocation rearrangement mechanisms that result from protonation of the starting olefins.

Synthesis of estolides from oleic and saturated fatty acids

“…The γ-and δ-lactones display different rates of reaction in the formation of amides from amines (16). This process enables the δ-lactone, the more reactive lactone, to selectively undergo substitution over the γ-lactone to provide high yields of highly desirable 5-hydroxy amides which serve as glucamide-derived biodegradable detergents (17,18).Estolides and estolide esters from meadowfoam (3,19,20), oleic acid (21), castor oil, or any source of hydroxy fatty acids (22,23) have shown promise as cosmetics, coatings, and biodegradable lubricants. Estolides and estolide esters compare favorably to commercially available industrial products such as petroleum-based hydraulic fluids, soy-based fluids, and petroleum oils, and usually outperform the competition (5).…”

“…Estolides and estolide esters compare favorably to commercially available industrial products such as petroleum-based hydraulic fluids, soy-based fluids, and petroleum oils, and usually outperform the competition (5). Many estolide ester derivatives have superior biodegradability and lubricating properties compared to petroleum oils (21).Estolides from oleic acid have been explored intensively in our laboratory (1)(2)(3)(4)9,20,21). These estolides were synthesized under various acidic conditions (Scheme 1), with mineral acids providing the best yields and physical properties (2).…”

“…Estolides and estolide esters from meadowfoam (3,19,20), oleic acid (21), castor oil, or any source of hydroxy fatty acids (22,23) have shown promise as cosmetics, coatings, and biodegradable lubricants. Estolides and estolide esters compare favorably to commercially available industrial products such as petroleum-based hydraulic fluids, soy-based fluids, and petroleum oils, and usually outperform the competition (5).…”

Natural estolides produced by Pseudomonas sp. 42A2 grown on oleic acid: Production and characterization

“…Other unsaturated FA monomers containing various functionalities on the carbon chain such as petroselenic acid (cis-6-octadecenoic acid), linoleic acid [9(Z),12(Z)-octadecadienoic acid], and hydroxy-FA have been used for estolide synthesis (4)(5)(6). Recently, lipases isolated from Candida rugosa, Rhizomucor miehei, Pseudomonas, and Alcaligenes were found suitable for estolide synthesis in vitro using δ-lactones or hydroxy FA of various chain lengths.…”

“…Estolides were first synthesized by high-pressure condensation of oleic acid over acidic clays (4,5). Other unsaturated FA monomers containing various functionalities on the carbon chain such as petroselenic acid (cis-6-octadecenoic acid), linoleic acid [9(Z),12(Z)-octadecadienoic acid], and hydroxy-FA have been used for estolide synthesis (4)(5)(6).…”