Dipole moments and molecular conformation in aromatic diazoketones

Abstract

Dipole moment data show that in para-substituted aromatic diazoketones the cis–trans-equilibrium at the COCHN₂ grouping, in contrast to diazoacetone, is almost entirely shifted to the cis-conformer; there is no indication of a rapid interconversion between the two conformers. The C–C–C angle at the carbonyl group is presumably larger than in the aliphatic compounds, owing to steric hindrance.