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United States Department of Agriculture

Agricultural Research Service

Title: Proton NMR: a convenient method for determining 2-monoacylglycerol acyl migration

Authors
item Compton, David
item Vermillion, Karl
item Laszlo, Joseph

Submitted to: American Oil Chemists' Society Meeting
Publication Type: Abstract Only
Publication Acceptance Date: November 14, 2006
Publication Date: May 13, 2007
Citation: Compton, D.L., Vermillion, K., Laszlo, J.A. 2007. Proton NMR: A convenient method for determining 2-monoacylglycerol acyl migration [abstract]. American Oil Chemists' Society. p. 16.

Technical Abstract: The acyl migration kinetics of neat (not exposed to solvent) 2-monoacylglycerol (2-MAG) to form 1-monoacylglycerol (1-MAG) was determined using proton NMR spectroscopy to monitor the B-proton integration ratios of the two species over time. 2-MAG was synthesized by the Novozym 435-catalyzed alcoholysis of soybean oil and isolated by solvent extraction or molecular distillation at a mole fraction of 0.94 relative to total MAG. The kinetic parameters of the neat 2-MAG acyl migration were investigated over the temperature range of 23 to 80 deg C. The 2-MAG mol fraction remained unchanged at 23 deg C over the course of 168 h and reached an equilibrium of X(2-MAG) = 0.09 at only 80 deg C. Modeling of the kinetics data revealed a 2-MAG half life of 3,500 h and 22.8 h at 23 and 80 deg C, respectively, with an activation energy of 79.0 +/- 6.5 kJ/mol. 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 NMR spectroscopy), requiring no sample manipulation and minimizing the deleterious effects of high temperatures and solvent exposure.

Last Modified: 9/10/2014
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