Critical examination of the 1H NMR spectra of aryl epoxides

Abstract

AbstractThe proton chemical shift of several derivatives of styrene oxides have been obtained in different solvents in order to check the relative importance of different contributions to the shielding of oxirane protons. It seems likely that ‘ring current’ and electrostatic effects can explain differences within the several compounds examined. An investigation of the conformational requirements of the phenyl group in these systems shows that the preferred conformation present in styrene oxide is also likely to be maintained in other compounds, where groups cis and trans to the phenyl ring are present. A discussion of the possibility of employing ‘ring currents,’ obtained both in the Johnson and Bovey scheme and with an SCF treatment for conformational analysis is given and it seems that this contribution, when considered alone, can only give very approximate information regarding the geometrical pattern of the molecule.