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The infrared spectra of aromatic compounds

1955; Elsevier BV; Volume: 7; Linguagem: Inglês

10.1016/0371-1951(55)80003-3

1873-3816

Marvin Margoshes, V. A. Fassel,

Chemical Reactions and Mechanisms

An empirical study has been made of the infrared spectra of aromatic compounds to determine the effect of substituent groups or some of the vibrations of the aromatic nucleus. In this paper particular attention is devoted to the out-of-plane C-H bending vibrations between 625 and 900 cm−1. For monosubstituted benzenes of the type (phenyl)nM, where n is the valence of the substituent atom M, the frequency of the absorption band between 725 and 820 cm−1 decreases linearly with the reduced mass of the diatomic group M -carbon. Most monosubstituted benzenes not of the type (phenyl)nM also show some correlation between the frequency of this band and the mass of the atom attached to the ring, but certain substituents produce anomalous shifts of this band. For disubstituted benzenes the effect of the substituents on the frequencies of some of the out-of-plane vibrations can be correlated with the effect of the same substituents on the 725 to 820 cm−1 band in monosubstituted benzenes.