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ARS Home » Midwest Area » Peoria, Illinois » National Center for Agricultural Utilization Research » Bio-oils Research » Research » Publications at this Location » Publication #404950

Research Project: Development of New Value-Added Processes and Products from Advancing Oilseed Crops

Location: Bio-oils Research

Title: Synthesis and characterization of estolide diamides for use as thickeners

item Cermak, Steven - Steve
item ISBELL, TERRY - Former ARS Employee
item Kenar, James - Jim
item Vermillion, Karl
item Winfield, Demichael

Submitted to: Association for the Advancement of Industrial Crops Conference
Publication Type: Abstract Only
Publication Acceptance Date: 6/6/2023
Publication Date: 8/27/2023
Citation: Cermak, S.C., Isbell, T.A., Kenar, J.A., Vermillion, K., Winfield, D.D. 2023. Synthesis and characterization of estolide diamides for use as thickeners [abstract]. Association for the Advancement of Industrial Crops Conference. p. 86.

Interpretive Summary:

Technical Abstract: A series of diamides were synthesized from normal fatty chain fatty acids (oleic and erucic), hydroxy fatty acids (9-hydroxy stearate, 12-hydroxy stearate, ricinoleic and lesquerolic) and estolides (oleic estolide, laurate-capped 9-hydroxy and 12-hydroxy stearate estolides, laurate-capped ricinoleic and lesquerolic estolides, and oleic estolides-capped 12-hydroxy stearic estolide). The diamides were synthesized with stoichiometric amounts of carboxylic acid to diamide and reactions were run without catalyst at 150 deg. C. for 24 h. Reaction yields for the formation of diamide ranged from 72-99% with purities greater than 90% where crystallization from an appropriate solvent gave nearly pure diamides. Diamide formation with the estolides did cause some transamination with the estolide linkage generating free hydroxy-containing mixed diamides. The hydroxy diamides could be esterified at the free hydroxy moiety using tin(II)octoate as a catalyst at 130 deg. C. in nearly quantitative yields when excess lauric acid was used. Kugelrohr distillation was utilized to remove excess lauric acid after the amination reaction was complete which yielded laurate-capped estolide diamides in purities >90%. All diamides were then evaluated for their ability to form gels in both poly alpha olefins (POA) and mineral oils at 0.5 and 1.0 w/w%. The estolide diamides all formed gels in the mineral oils, whereas the normal chain fatty acids and hydroxy fatty acids increased the viscosity significantly but failed to form gels.