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Acyl Migration Kinetics of 2‐Monoacylglycerols from Soybean Oil via 1 H NMR
Author(s) -
Compton David L.,
Vermillion Karl E.,
Laszlo Joseph A.
Publication year - 2007
Publication title -
journal of the american oil chemists' society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.512
H-Index - 117
eISSN - 1558-9331
pISSN - 0003-021X
DOI - 10.1007/s11746-007-1049-1
Subject(s) - chemistry , kinetics , soybean oil , solvent , nuclear magnetic resonance spectroscopy , mole fraction , proton nmr , chemical kinetics , spectroscopy , nuclear chemistry , analytical chemistry (journal) , chromatography , medicinal chemistry , organic chemistry , physics , food science , quantum mechanics
The acyl migration kinetics of neat 2‐monoacylglycerol (2‐MAG) to form 1‐MAG was determined using 1 H NMR spectroscopy to monitor the β‐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 ( X 2‐MAG ) of 0.94 relative to total MAG. The kinetics parameters of the neat 2‐MAG acyl migration were investigated over the temperature range of 23–80 °C. The 2‐MAG mol fraction remained unchanged at 23 °C over the course of 168 h and reached an equilibrium of X 2‐MAG = 0.09 at only 80 °C. Modeling of the kinetics data revealed a 2‐MAG half life ( t 1/2 ) of 3,500 and 22.8 h at 23 and 80 °C, respectively, with an activation energy of 79.0 ± 6.5 kJ mol −1 . The use of 1 H NMR spectroscopy proved an expedient method for monitoring the acyl migration in 2‐MAG compared to other reported methods (e.g. GC, HPLC, and 13 C‐NMR spectroscopy), requiring no sample manipulation and minimizing the deleterious effects of high temperatures and solvent exposure.