Chemical Shifts in the N.M.R. Spectra of Substituted Xylenes

Fraser, Robert R.

doi:10.1139/v60-300

Cited by 57 publications

(8 citation statements)

References 11 publications

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“…Variations in the polarization of tlie C-1-1 bond therefore should be more important and tlie electronic effects of substituents should influence the formyl shifts in a predictable manner. Similar correlations have been discussed for a number of other systems (7,(19)(20)(21)(22).…”

Section: General Considerationssupporting

confidence: 75%

Nuclear Magnetic Resonance Studies: Part I. The Chemical Shift of the Formyl Proton in Aromatic Aldehydes

Klinck¹,

Stothers²

1962

Can. J. Chem.

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Chemical shift data for the formyl proton in some 30 aromatic aldehydes are reported. It was found that 111eta-and para-substituted benzaldehydes exhibited this peal; in the range 9.85-10.20 6, while ortho-substituted compounds appear a t lower held, 10.20-10.50 6 ; the former shifts show an approximate correlation with the Hammett sig-nla parameter. Evidence for steric inhibition of resonance is presented for some ortho-substituted compounds and some interesting solvent effects are discussed. IXTRODUCTIONAlthough it is well l

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Section: General Considerationssupporting

confidence: 75%

Nuclear Magnetic Resonance Studies: Part I. The Chemical Shift of the Formyl Proton in Aromatic Aldehydes

Klinck¹,

Stothers²

1962

Can. J. Chem.

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“…In recent years many examples of correlations between the effect of substituents on the chemical shift (abbreviated to SCS) of a proton on a benzene ring and the Hammett sigma value of the substituents have been found (1)(2)(3). In addition similar correlations have been observed for protons in the side chains of toluenes (4-7), phenols (8), anisoles (9), dihydrocinnamic acids ' (lo), cyclopropanes (1 l), and benzonorbornenes (12).…”

mentioning

confidence: 70%

“…While the sensitivity of fluorine and proton nuclei to substituent effects is different, many similarities in their correlations do exist. In the case of aromatic protons, they too are influenced to a large extent by the resonance effect of the substituent as measured by o : (1).…”

mentioning

confidence: 99%

Effect of substituents on the chemical shift of benzylic protons

Fraser¹,

Gurudata²,

Renaud³

et al. 1969

Can. J. Chem.

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The chemical shift of the benzylic protons in fifteen series of para-substituted toluenes bearing different groups in the alpha position are reported. In each series a plot of the chemical shift in tau units of the benzylic protons against the Hammett o value of thepara substituent is linear. The slopes of these plots vary from -0.20 to +0.01 p.p.m./o. The variation of slopes appears to be conformationally dependent, an observation at odds with current theory. In two rigid systems having the same geometry the slope has been found to vary from -0.12 to -0.18 indicating a dependence on other factors as well. The effect of solvent on the slopes has been determined, and shows no correlation with solvent dielectric properties.

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“…spectra of a considerable number of 1-substituted 2,6-dimethylbenzene derivatives have been studied and an attempt made t o relate the observed chemical shifts of the ring protons to steric effects of the substituents and Hammett sigma values (1). Since the degree of interaction of various substituents with adjacent methyl substituents is not generally known with any accuracy it seemed worthwhile to make a further study of very large substituents in which deviations from coplanarity are well known to be great and hence mesomeric effects will be very markedly reduced.…”

Section: Introductionmentioning

confidence: 99%