EVALUATION OF THE 13C-NMR SIGNALS OF SATURATED CARBONS IN LONG-CHAIN COMPOUNDS

Authors: Knothe, Gerhard; Nelsen, Terry

Submitted to: Journal of the Chemical Society Perkin Transactions 2
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/19/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Scientists and technologists need to know the composition of
materials with which they work and have to be able to
analyze mixtures of materials rapidly. Vegetable oils and
their derivatives mainly constitute mixtures of various
compounds called fatty acids. Such mixtures occur in many
commercial products derived from vegetable oils. The method
developed here will allow for rapid analyses of vegetable
oil-derived mixtures by a mathematical equation which can
"automate" the evaluation of such analyses.

Technical Abstract: The 13C-NMR shift values of saturated carbons in long chain
compounds can be mathematically approximated by equations of
the kind s = -ax-b + cx-d + e which are similar to those for
the Lennard Jones potential. Here s is the chemical shift of
a carbon atom and x is the position in the chain of this
atom or a functional group influencing its shift value.
Equations were determined for selected saturated carbons of
methyl octadecanoate, cis- and trans- octadecenoic acids,
methyl cis-octadecenoates, methyl oxooctadecanoates, methyl
hydroxyoctadecanoates, methyl acetoxyoctadecanoates and
methyl epoxyoctadecanoates. Excellent correlation
(regression coefficients in most cases >0.99) of
experimental and theoretical data was achieved. These
equations can be used for predicting 13C NMR shift values of
saturated carbons in long chain compounds.