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Fatty Acid Methyl Esters with Two Vicinal Alkylthio Side Chains and Their NMR Characterization
Author(s) -
Knothe Gerhard,
Steidley Kevin R.
Publication year - 2017
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/s11746-017-2959-1
Subject(s) - chemistry , diastereomer , moiety , vicinal , yield (engineering) , carbon 13 nmr , alkene , proton nmr , fatty acid , nmr spectra database , double bond , mass spectrometry , side chain , organic chemistry , catalysis , medicinal chemistry , stereochemistry , chromatography , spectral line , materials science , physics , astronomy , metallurgy , polymer
The addition reaction of dimethyl disulfide (DMDS) to double bonds in alkenes and monounsaturated fatty acid esters in the presence of iodine or other catalysts to give bis(methylthio) derivatives has largely served analytical purposes in mass spectrometry with scattered reports on the addition of other disulfides to alkenes also existing. In this work, this iodine‐catalyzed reaction was expanded to include the addition of other dialkyl disulfides (RSSR; R=ethyl, propyl, butyl, iso‐propyl) besides DMDS to the double bonds in monounsaturated fatty acid methyl esters with 16, 18, 20, and 22 carbon atoms in the fatty acid chain to give the corresponding methyl 1,2‐bis(alkylthio)alkanoates. The products are obtained in high to moderate yield after a facile purification procedure and are analytically characterized not only by mass spectrometry but also 1 H and 13 C NMR. The threo and erythro diastereomers obtained from ( Z ) and ( E ) fatty acid methyl esters, respectively, can be easily distinguished by the NMR shifts of the protons and carbons in and close to the 1,2‐bis(alkylthio) moiety. Various other effects in the NMR spectra are discussed. The 1,2‐bis(alkylthio) derivatives of a symmetrical alkene, 7( E )‐tetradecene, serve to confirm the NMR assignments besides NMR techniques such as 2D correlations and DEPT. The compounds may show properties of interest for various applications.