1H and 13C NMR studies of para-substituted benzaldoximes for evaluation of the electron donor properties of substituted amino groups †

Abstract

1 H and 13C NMR spectra of seventeen (E)-benzaldoximes and three acetophenone oximes, both carrying substituted p-amino groups, have been recorded and discussed from the point of view of substituent effect. The resonance effect of these substituents is not transmitted strongly to CHNOH group. However, it is found that the chemical shift of Cpara depends linearly on σRo values. This dependence has been used to calculate the resonance substituent constants for the less common amino groups and the 1-pyrrolidine group is found to be the most powerful electron donor among the substituents studied.