Location: Bio-oils Research Unit
Title: Synthesis and physical properties of petroselinic based estolide esters Authors
Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 11, 2010
Publication Date: January 1, 2011
Citation: Cermak, S.C., Isbell, T., Evangelista, R.L., Johnson, B.L. 2011. Synthesis and physical properties of petroselinic based estolide esters. Industrial Crops and Products. 33:132-139. Interpretive Summary: An understanding of how lubricating oils behave in cold weather is of significant importance to the scientific community. As scientists, we must understand the chemistry that takes place to cause molecules to behave as they do; a better understanding will allow chemists and formulationists to create new products from agricultural sources with superior industrial properties. Thus, we must explore a host of oils from new crops as a potential for lubricating oils. This project investigated the development of a series of compounds called estolides which have been made from a new crop oil called coriander. Coriander contains a different type of fatty acid than that found with oleic sources. The position of the unsaturation (i.e., double bond) is located in a different position on the fatty acid chain. This will allow for the synthesis of an estolide not previously developed and, thus, no physical property measurements exist for such a family of compounds. Understanding how the structure of this different estolide will affect the molecule’s performance in cold weather applications will be evaluated. It was found that the position of the estolide had a profound effect on the low temperature properties, i.e., the position does influence the physical properties. Developing estolides of different types and sizes will lead to a better understanding of how an estolide molecule behaves under certain conditions; ARS scientists will have the capability to design “smart molecules”. The goal is to design molecules that meet an application versus the old technology of developing an oil and finding applications for the oil.
Technical Abstract: A new series of petroselinic (Coriandrum sativum L.)-based estolide 2-ethylhexyl (2-EH) esters were synthesized, as the capping material varied in length and in degrees of unsaturation, in a perchloric acid catalyzed one-pot process with the esterification process incorporated into an in situ second step to provide the coriander estolide 2-EH ester. Their kinematic viscosities ranged from 53 to 75 cSt at 40°C and 9.1 to 14 cSt at 100°C with a viscosity index (VI) 151 to 165. The caprylic capped coriander estolide 2-EH ester had the lowest low-temperature properties (pour point = -33°C and cloud point = -33°C), while the coco-coriander estolide 2-EH ester produced an estolide with modest low-temperature properties (pour point = -24°C and cloud point = -25°C). The coco-coriander estolide 2-EH ester was explored for the ability to resist oxidative degredation with the use of a biodegradable additive package added in 1.5, 3.5, or 7.0% units based on weight. The oxidative stability increased as the amount of stability package increased (RPVOT times 65-273 min). Along with expected good biodegradability, these coriander estolide 2-EH esters had acceptable properties that should provide a specialty niche in the U.S as a bio-based lubricant.