THE FIRST OVERTONE N-H STRETCHING BANDS OF RING-SUBSTITUTED ANILINES AND THEIR RELATION TO INTRAMOLECULAR HYDROGEN BONDING
Loading...
Date
1964
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Ohio State University
Abstract
The first overtone N-H symmetric stretching bands of several ortho-substituted anilines have been reported to consist of two components. Some workers have attributed the doublet to the presence of an intramolecular hydrogen bond with a double minimum potential $function,^{1, 2}$ while others have assigned the two bands to “free” and “bonded” N-H $groups.^{3, 4}$ Recent work in this laboratory has shown that the spectra of cyclohexane solutions of aniline and its meta- and parasubsituted derivatives also exhibit the doublets. When carbon tetrachloride is used as the solvent, as has been the case in all previous work on this problem, the N-H bands are broadened to such an extent that the doublets are clearly resolved for only a few ortho-substituted derivatives. These observations have led us to assign the low frequency component of the doublet to the first overtone symmetric stretching vibration and the high frequency component to a sum mode of the symmetric and asymmetric vibrations. The increased separation of the two components which is observed with compounds containing an intramolecular hydrogen bond can be related to the larger separation of the fundamental N-H stretching bands and to the effects of bonding on the anharmonicities of the various vibrations. The spectra of a few mono- and dideuterated amines were measured and found to be consistent with the new band assignments. $^{1}$ A. N. Hambly, Rev. Pure and Appl. Chem. (Australia) 11, 212 (1961). $^{2}$ P. J. Krueger, 46th Annual Conference of the Chemical Institute of Canada, Toronto, June 5-8, 1963. $^{3}$ K. B. Whetsel, W. E. Roberson and M. W. Krell, Anal Chem. 50, 1598 (1958). $^{4}$ P. J. Krueger, Can. J Chem. 41, 363 (1963).
Description
Whetsel Kermit B.
Author Institution: Tennessee Eastman Company, Division of Eastman Kodak Co.
Author Institution: Tennessee Eastman Company, Division of Eastman Kodak Co.