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United States Department of Agriculture

Agricultural Research Service

Title: Evaluation of the Olefinic Proton Signals in the 1h-Nmr Spectra of Allylic Hydroxy Groups in Long-Chain Compounds

Authors
item Knothe, Gerhard
item Bagby, Marvin

Submitted to: Chemistry and Physics of Lipids
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 8, 1996
Publication Date: N/A

Interpretive Summary: Fats and oils and their partially hydrogenated products, such as animal fats, tallow and seed oils like soybean, sunflower and rapeseed, consist of fatty acids of many structures. Scientists and technologists need to better understand the composition of the materials with which they work. One structural characteristic of fatty acids important to the scientist and technologist, working to develop value-added industrial or food products, is the location of the unsaturation or other certain specific structural features present in these acids. Mathematical equations were developed that provide an improved and simplified procedure to determine position of certain structural features using magnetic resonance data. This method provides a rapid approach to analyzing complex mixtures of fatty acids contained in fats and oils.

Technical Abstract: The positional isomers of monounsaturated long-chain fatty compounds containing allylic hydroxy groups (shown for trans double bonds) can be distinguished by 1H-NMR spectroscopy. The differences in the chemical shifts of the olefinic protons can be expressed as rational functions (the differences being proportional to the negative third power of the position of the unsaturation) or logarithmic functions (the position of the unsaturation raised as power). The present results on more sensitive 1H-NMR spectra complement previous work on the 13C-NMR spectra of these compounds. Theoretical models for explaining shifts in 13C-NMR therefore also apply to 1H-NMR.

Last Modified: 9/10/2014
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