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Australian Journal of Chemistry Australian Journal of Chemistry Society
An international journal for chemical science
RESEARCH ARTICLE

Resonance and solvent effects on absorption spectra of some 2- and 4-(–M)-substituted aniline derivatives

T Yokoyama, RW Taft and MJ Kamlet

Australian Journal of Chemistry 36(4) 701 - 709
Published: 1983

Abstract

The N-H protons of N-methyl-2-X-aniline derivatives remain intramolecularly hydrogen bonded in HBA (hydrogen bond acceptor) solvents where X = COOMe and NO2, but form intermolecular hydrogen bonds to the HBA solvents where X = CN. The order of response of vmax to solvent HBA basicity for the Cl → C2 bands of N-unsubstituted-2-(-M)-substituted aniline derivatives and the Cl → C4 bands of 4-(-M)-substituted aniline derivatives follows the orders of the hydrogen bond donor acidities of the amine protons, which are determined primarily by the mesomeric effects of the 2- and 4-substituents. The spectral data indicate that intramolecularly hydrogen bonded 2-(-M)-substituted aniline derivatives are near sp2 hybridized in non-HBA solvents and, unlike several 4-substitute anilines, do not undergo significant rehybridization in HBA solvents. Bath ochromic shifts resulting from hydrogen bonds by corresponding 2- and 4-substituted aniline derivatives to HBA solvents are of similar magnitudes.

https://doi.org/10.1071/CH9830701

© CSIRO 1983

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