The dipole moments, molar Kerr constants, and solution-state conformations of some substituted benzamides

Abstract

The dipole moments and molar Kerr constants are reported for 24 substituted benzamides as solutes in dioxan. These data are analysed to indicate the preferred solution conformations. Our results indicate that for a given ring substituent the dihedral angle between the planar amide group and the benzene ring is similar for both the 3- and 4-substituted benzamides but less than that for the 2-substituted isomer. For the 3-substituted benzamides both ‘cis-’ and ‘trans-’-conformers contribute to the observed dipole moment and molar Kerr constant whereas for the 2-substituted species only that conformer with the CO bond of the amide group remote from the ortho-substituent is proposed.