13C and 1H NMR of α-Arylnitrones. Substituent Effects on the α-Position of α-(<i>p</i>-Substituted Phenyl)nitrones

Abstract

Abstract Substituent effects on the 13C and 1H NMR chemical shifts of the α-position of various α-(p-substituted phenyl)nitrones, α-phenyl-N-(1-cyano-2-methylpropyl)nitrones (1), α-phenyl-N-methylnitrones (2), and α-phenyl-N-phenylnitrones (3), have been investigated and the obtained results have been compared with data related to N-(p-substituted benzylidene)anilines (4) and reported data for p-substituted styrenes (5). The chemical shifts of the α-arylnitrones are well correlated with substituent constants by means of a linear combination of two empirical parameters, σi and σπ. Inductive effects predominate at the α-carbon but resonance effects predominate at the α-hydrogen.