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Two‐dimensional NMR studies of polyene systems. II. β‐carotene
Author(s) -
Wernly Jacques,
Lauterwein JÜRgen
Publication year - 1985
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1260230308
Subject(s) - chemistry , chemical shift , polyene , methylene , nuclear magnetic resonance spectroscopy , pulse sequence , coupling constant , spectroscopy , carbon 13 nmr satellite , spectral line , analytical chemistry (journal) , nmr spectra database , proton nmr , chloroform , stereochemistry , fluorine 19 nmr , nuclear magnetic resonance , organic chemistry , physics , particle physics , quantum mechanics , astronomy
Two‐dimensional NMR results are presented for β‐carotene in chloroform. J ‐resolved 1 H NMR spectroscopy allows the accurate determination of the chemical shifts and coupling constants for the olefinic protons. In order to obtain sufficient signal intensity in the projection spectrum for the HC‐7, HC‐10 and HC‐14 protons, spin decoupling of the long‐range coupled methyl and methylene protons was necessary. 1 H, 13 C chemical shift‐correlated NMR spectroscopy gave a relationship between the directly bonded olefinic CH pairs. Cross‐sections through each 13 C chemical shift allowed the assignment of the carbon resonances. Simulation of the cross‐sections was possible when the 180° carbon pulse was removed in the standard pulse sequence. It is shown that, under these conditions, the cross‐sections correspond to partial 13 CH satellite spectra.