Proton Resonance Spectra of Thiopyrones
Technical rept. no. 75
ILLINOIS UNIV AT URBANA WILLIAM A NOYES LAB
Pagination or Media Count:
The proton magnetic resonance spectra of 4-pyrone, 4-thiapyrone, 4-thiopyrone, and 4-thiothiapyrone were observed and analyzed. Comparisons of the experimental spectra with those calculated for all combinations of relative signs for the coupling constants indicate that in each molecule the coupling constants have the same sign, which presumably is positive. The average deviation between the observed line positions and those calculated for each of the various sign permutations is found to be a useful criterion in assigning the relative signs. The effect on the coupling constants of the introduction of sulfur into the molecule is discussed. The downfield shift of the midpoint of the spectra, found upon sulfur introduction, is interpreted in terms of an increased ring current.
- Organic Chemistry