13C-NMR of methyl, methylene and carbonyl carbon atoms of methyl alkenoates and alkynoates

BUS, J.; Sies, Izaäk; Jie, Marcel S. F. Lie Ken

doi:10.1016/0009-3084(76)90049-9

Cited by 102 publications

(38 citation statements)

References 6 publications

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“…This applied also to the allylic methine resonances; the ones adjacent to a cis double bond resonated at ı C 81.36-81.44 while those adjacent to a trans double bond at ı C 86.74-86.84. These findings agree with the 13 C NMR data on olefinic fatty esters (Bus et al, 1976;Gunstone et al, 1977) and on cis and trans monoene allylic monohydroperoxides from autoxidation of methyl oleate (Garwood et al, 1977;Frankel et al, 1984;Porter et al, 1994).…”

Section: Assignment Of the Nmr Spectrasupporting

confidence: 90%

NMR properties of conjugated linoleic acid (CLA) methyl ester hydroperoxides

Pajunen

Koskela

Hase

et al. 2008

Chemistry and Physics of Lipids

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Section: Assignment Of the Nmr Spectrasupporting

confidence: 90%

NMR properties of conjugated linoleic acid (CLA) methyl ester hydroperoxides

Pajunen

Koskela

Hase

et al. 2008

Chemistry and Physics of Lipids

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“…The geometry of the double bonds was determined based on the vicinal coupling constants ( 3 J = 15.2 Hz for a trans and 3 J ≈ 11.0 Hz for a cis double bond) and was further confirmed by characteristic chemical shifts of allylic methine and methylene carbons in the 13 C NMR spectrum. The chemical shift at δ 72.90 (C-13) was characteristic of an allylic methine carbon atom adjacent to a trans double bond (14) and the chemical shift at δ 27.68 (C-8) confirmed that the allylic methylene carbon was adjacent to a cis double bond (15,16).…”

Section: Resultssupporting

confidence: 55%

Stereochemistry of the hydroperoxides formed during autoxidation of CLA methyl ester in the presence of α‐tocopherol

Hämäläinen

Sundberg

Hase

et al. 2002

Lipids

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The initial steps in the autoxidation of CLA methyl ester are poorly understood. The aim of this study was to determine the stereochemistry of the hydroperoxides formed during autoxidation of CLA methyl ester in the presence of a good hydrogen atom donor. For this purpose, 9-cis,11-trans CLA methyl ester was autoxidized in the presence of alpha-tocopherol under atmospheric oxygen at 40 degrees C in the dark. The CLA methyl ester hydroperoxides were isolated, reduced to the corresponding hydroxy derivatives, and separated by HPLC. The stereochemistry of seven hydroxy-CLA methyl esters was investigated. The position of the hydroxy group was determined by GC-MS. The geometry as well as the position of the double bonds in the alkyl chain was determined by NMR. In addition, the 13C NMR spectra of six hydroxy-CLA methyl esters were assigned using COSY, gradient heteronuclear multiple bond correlation, gradient heteronuclear single quantum correlation, and total correlation spectroscopy experiments. The autoxidation of 9-cis,11-trans CLA methyl ester in the presence of a good hydrogen atom donor is stereoselective in favor of one geometric isomer, namely the 13-(R,S)-hydroperoxy-9-cis,11-trans-octadecadienoic acid methyl ester. Three types of conjugated diene hydroperoxides are formed as primary hydroperoxides: trans,trans hydroperoxides (12-OOH-8t,10t and 9-OOH-10t,12t), a cis,trans hydroperoxide with the trans double bond adjacent to the hydroperoxide-bearing carbon atom (13-OOH-9c,11t), and a new type of cis,trans lipid hydroperoxide with the cis double bond adjacent to the hydroperoxide-bearing carbon atom (8-OOH-9c,11t). In addition, three nonkinetic hydroperoxides (13-OOH-9t,11t, 8-OOH-9t,11t, and 9-OOH-10t,12c) are formed. This study supports the theory that CLA methyl ester autoxidizes at least partly through an autocatalytic free radical reaction. The complexity of the hydroperoxide mixture is due to formation of two different pentadienyl radicals. Moreover, the stereoselectivity in favor of one geometric isomer can be explained by the selectivity of the two previous steps: the preferential formation of a W-conformer of the pentadienyl radical over the Z-conformer, and regioselectivity of the oxygen addition to the pentadienyl radical.

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“…for acetylenes [84][85][86][87], allenes [15,69], conjugated acetylenes [10], conjugated dienes [5,85,88], trienes [89][90][91][92], tetraenes [8,91,93], conjugated olefin-acetylenes [3,11,72], cyclopropenes [14,83], epoxy [94], hydroxy [14,95,96], keto [95,97], and olefins (monoenes [84,85,87,98]; polyenes, methyleneinterrupted [99][100][101][102]; non-methylene-interrupted [98,103,104]). …”

Section: C Nuclear Magnetic Resonance Spectroscopymentioning

confidence: 99%

Screening analysis of unknown seed oils

Spitzer¹

1999

Fett/Lipid

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In the present paper, modern tools for the screening analysis of unknown seed oils have been reviewed. The known plant fatty acid structures have been divided into three groups (usual, unusual nonoxygenated, unusual oxygenated fatty acids) and examples for each class are presented. Moreover, the importance of chemotaxonomy for the screening analysis of some lipid components is discussed. The main part of the work is focussed on various aspects of preliminary seed oil analyses for the detection of unusual fatty acids and lipid classes and the analysis of fatty acid derivatives by gas chromatography and gas chromatography/mass spectrometry. Furthermore, some useful methods to obtain rapid information on the configuration of double bonds are cited. The paper concludes with a scheme for the detection of unusual fatty acids and lipid classes in seed oils.

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13C-NMR of methyl, methylene and carbonyl carbon atoms of methyl alkenoates and alkynoates

Cited by 102 publications

References 6 publications

NMR properties of conjugated linoleic acid (CLA) methyl ester hydroperoxides

NMR properties of conjugated linoleic acid (CLA) methyl ester hydroperoxides

Stereochemistry of the hydroperoxides formed during autoxidation of CLA methyl ester in the presence of α‐tocopherol

Screening analysis of unknown seed oils

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