1 H nuclear magnetic resonance spectral parameters of toluene. Implications for conformational analysis and isotope shifts
1985; NRC Research Press; Volume: 63; Issue: 10 Linguagem: Inglês
10.1139/v85-431
ISSN1480-3291
AutoresTed Schaefer, Rudy Sebastian, Glenn H. Penner,
Tópico(s)Analytical Chemistry and Chromatography
ResumoA precise analysis of the 1 H nmr spectrum of toluene as a dilute solution in carbon disulfide yields a revised set of spectral parameters. The chemical shift of the para proton lies 12.6 ppb to low frequency of that of the ortho protons at 300 K. The ring proton chemical shifts are discussed and compared with 1 H and 3 H shifts observed in carbon tetrachloride. The long-range couplings between methyl and ring protons can be said to be quantitatively understood in terms of σ and σ–π electron transmitted mechanisms. The changes observed in these three couplings in phenylacetaldehyde can be quantitatively reproduced in terms of these mechanisms and also illustrate how these changes are direct measures of the conformational preferences in this molecule.
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