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Solvent Effect of Dimethyl Sulfoxide on the Chemical Shifts of Phenyl Vinyl Ketones
Author(s) -
Lien JinCherng,
Chen ShengChih,
Huang LiJiau,
Kuo ShengChu
Publication year - 2004
Publication title -
journal of the chinese chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.329
H-Index - 45
eISSN - 2192-6549
pISSN - 0009-4536
DOI - 10.1002/jccs.200400127
Subject(s) - chemistry , benzene , dimethyl sulfoxide , solvent , moiety , chemical shift , ring (chemistry) , steric effects , molecule , medicinal chemistry , solvent effects , nmr spectra database , photochemistry , spectral line , stereochemistry , organic chemistry , physics , astronomy
In our study on the 1D and 2D NMR spectra of synthetic chalcones in DMSO‐ d 6 , we found that, contrary to our expectation, the signals of α‐carbon correlated to the olefinic protons resonating at lower field whereas the signals of β‐carbon correlated to the olefinic protons resonating at higher field in the spectra of chalcones. To further investigate such solvent effect, four α,β‐unsaturated ketones were prepared and studied separately in CDCl 3 and DMSO‐ d 6 . The result indicated that the α,β‐unsaturated ketones that possess benzoyl moiety experienced solvent effect in DMSO‐ d 6 to result in an anomalous chemical shift. The shift arose from the complexation of solute molecule with DMSO that fixed the steric conformation of solute molecule so that H β was kept apart from its benzene ring whereas its H α became more accessible by its benzene ring. Thus, these two olefinic protons would experience a different extent of anisotropic effect exerted by the neighboring benzene ring.