Nuclear magnetic resonance and the conformation of some derivatives of Michler's ketone

¹H NMR spectra are reported for Michler's ketone and twenty of its derivatives, along with ¹³C chemical shifts for five of the compounds. ¹H chemical shifts show only small changes with increasing substitution at the sterically hindered 2-position. Estimates of the dihedral angle between the benzene ring and C? CO? C planes have been obtained from the chemical shifts of C?O and 4-C for ketones 1, 3, 5, 15 and 16 . These angles are both internally consistent and very similar to dihedral angles determined by other methods for corresponding compounds in the benzophenone series.