Substituent Chemical Shifts of (E)-1-Aryl-3-thienylpropen-1-ones

초록

Substituent chemical shifts were examined for the 2- and 3-thiophene derivatives of chalcone and compared to the thiophene series of derivatives with the phenyl series. The chemical shift values for the alpha-carbons of the enones showed and inverse correlation with the Hammett sigma values, but the correlation coefficients were moderate (r = 0.836 - 0.878). On the other hand, the beta-carbons showed a normal correlation with excellent correlation coefficients (r = 0.994). The absolute magnitude of the rho values for the alpha-carbon are about half of those of the beta-carbon. The observation may be the result fa through-space transition oldie electronic effect of the substituents in addition to the through bond transition.

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