Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/15/2007
Publication Date: 4/1/2007
Citation: Compton, D.L., Vermillion, K., Laszlo, J.A. 2007. Acyl migration kinetics of 2-monoacylglycerols from soybean oil via 1h Nuclear Magnetic Resonance (NMR). Journal of the American Oil Chemists' Society 84(4):343-348. Interpretive Summary: The goal of our project is to develop new, environmentally benign methods to help convert a portion of the excess soybean oil produced in the U.S. to new, value-added uses, such as nutritional, industrial and cosmetic ingredients. Soybean oil consists of a glycerol backbone with three attached fatty acid groups. We have developed an environmentally friendly method of exchanging one or two of the fatty acid groups of the soybean oil for another natural plant component, ferulic acid. These patented ferulic acid modified vegetable oils, called SoyScreen(TM), have shown promise as active ingredients in anti-aging and skin-rejuvenating cosmetic formulations. To increase production capacity of SoyScreen(TM) while reducing production costs, we have investigated the process of removing two fatty acid groups prior to attaching the ferulic acid. The removal of the two fatty acid groups from soybean oils results in an oil called 2-monoacylglycerol (2-MAG). The current investigation was to develop a new, expedient method to determine the stability of 2-MAG at different temperatures over time. This information will aid in the scale-up of SoyScreen(TM) production and process optimizations. New, value added uses for vegetable oils such as SoyScreen(TM) are beneficial to producers by increasing the value of their commodity crops. The new method for monitoring 2-MAG stability will be of use to others researching the functionalization of vegetable oils.
Technical Abstract: The acyl migration kinetics of neat 2-monoacylglycerol (2-MAG) to form 1-monoacylglycerol (1-MAG) was determined using proton NMR spectroscopy to monitor the beta-proton integration ratios of the two species over time. 2-MAG was synthesized by the Novozym 435-catalyzed alcoholysis of soybean oil and isolated at a 2-MAG mole fraction of 0.94 relative to 1-MAG. The kinetic parameters of the neat 2-MAG acyl migration were investigated over the temperature range of 23 to 80 degree C. The 2-MAG mol fraction remained unchained at 23 degree C over the course of 168 h and reached an equilibrium of X2-MAG = 0.09 at only 80 degree C. Modeling of the kinetic data revealed a 2-MAG half life of 3,500 h and 22.8 h at 23 and 80 degree C, respectively. The use of proton NMR spectroscopy proved an expedient method for monitoring the acyl migration in 2-MAG compared to other reported methods (e.g. GC, HPLC and carbon-13 NMR spectroscopy), requiring no sample manipulation and minimizing the deleterious effects of high temperatures and solvent exposure.