Solvent effects on the infrared spectra of anilines. IV. Secondary aromatic amines and amides with trifluoromethyl or phenyl as ortho substituents

Abstract

The N-H stretching frequencies of five N-substituted anilines with trifluoro- methyl or phenyl as ortho substituent have been measured in a variety of solvents. Elevation of v(NH) by steric compression is observed. The frequency shifts observed for N-methyl-2-phenylaniline fit none of the three classes of solvent shift behaviour recognized for other ortho-substituted secondary amines. The results confirm that solvent shifts of v(NH) cannot be used to distinguish between the steric and hydrogen bonding properties of the ortho substituent.