Chemistry and physical properties of estolides

Abstract

Estolides are a developing class of natural and synthetic compounds that have been synthesized from hydroxy oils like castor and lesquerella or by the condensation of fatty acids across the olefin of a second fatty acid. Castor and lesquerella estolides are derived from either their triglycerides or their free fatty acids utilizing their hydroxyl moiety to establish the estolide bond. The triglyceride estolides have pour points of 9 to –36ºC but suffer poor oxidative stability with RPVOT times of 29 – 52 minutes even with 1% of an anti-oxidant package incorporated into the samples. In contrast to the triglyceride estolides of castor and lesquerella, the estolides from lesquerolic and ricinoleic acids have very good pour points of –36 to –54ºC. Estolides derived from the acid catalyzed condensation of oleic acid with a variety of fatty acids can be made in good yield and posses a wide range of physical properties. Of particular interest are the saturated capped estolides of oleic that have both good low temperature properties (pour point –5 to – 39ºC) and good oxidative stability. Estolides from meadowfoam fatty acids do not have good low temperature properties but have been extensively used in cosmetics where they provide good moisturizing properties.

Keywords

• castor
• estolide
• lesquerella
• oleic acid
• physical properties
• synthesis