Thermodynamic parameters in the conformational equilibria of acetyldiazomethane, 1-acetyl-1-diazoethane, and benzoyl(diazo)phenylmethane using infrared spectroscopy

Abstract

The integrated intensities of the two i.r. peaks resulting from the asymmetric N–N stretching vibration of acetyldiazomethane, 1-acetyl-1-diazoethane, and benzoyl(diazo)phenylmethane have been measured as a function of temperature in carbon tetrachloride. From the temperature dependence analysis of the relative areas, thermodynamic parameters for the cis–trans-conformational equilibria of these α-diazoketones have been obtained. Such parameters are discussed in terms of various contributions deriving from dipolar interaction forces and favourable steric arrangements which seems to indicate in the three cases a greater stability of the cis-conformer.