THE STUDY OF HYDROGEN BONDING AND RELATED PHENOMENA BY ULTRAVIOLET LIGHT ABSORPTION: PART V. INTRAMOLECULAR HYDROGEN BONDING IN ANILINES AND PHENOLS

Abstract

Information concerning intramolecular hydrogen bonding in phenols and anilines can be obtained from ultraviolet spectra by a variety of methods. One method is to note the spectral changes observed between the corresponding o-substituted phenols and anisoles. A second method is to compare the spectral changes between o-substituted phenols or anilines and the corresponding meta isomers. A third method is to note the absence of an appreciable spectral change, on altering the solvent conditions, which may also indicate the formation of an intramolecular hydrogen bond. The conclusions deduced from the three methods confirm previously stated generalizations concerning the nature of the hydrogen bond. One notable exception is that the spectral changes ascribed to the intramolecular hydrogen bond in o-nitrophenol can be explained in terms of an electrostatic model of the hydrogen bond.