Effect of substituents on the 13C NMR chemical shifts of para-substituted α-phenyl-β-pyridylacrylic acids

Article abstract of DOI:10.1016/S0022-2860(96)09563-4

The ¹³C NMR spectra of para-substituted α-phenylcinnamic and 3- and 4-pyridylacrylic acids, with a wide range of substituents effects, were determined in deuterated dimethylsulfoxide (DMSO-d₆). The effect of substituents in both the α-phenyl and β-pyridine groups in these acids is investigated using linear free energy relationships and multiple regression analysis as applied to ¹³C NMR chemical shifts of the C(α) and C(β) of the ethylenic bond and the carboxylic group carbon. Dissection of the α-phenyl substituent effects into the inductive and resonance components, using the dual substituent parameter (DSP) method, points to a blend of inductive and resonance effects in the π-electronic system.