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

Intramolecular hydrogen bonding in some ortho-nitrodiphenylamines and related compounds. A proton magnetic resonance study

DJ Gale and JFK Wilshire

Australian Journal of Chemistry 25(10) 2145 - 2154
Published: 1972

Abstract

.Proton magnetic resonance spectra of a wide variety of substituted 2-nitro- and 2,4-dinitro-diphenylamines and related compounds reveal that long-range coupling occurs between the NH proton and the 5-proton of the nitrophenyl ring in non-polar or weakly polar solvents. However, in the case of the 2,4-dinitrodiphenyl- amines, this coupling is absent in highly polar solvents, except when the non-nitrated ring carries powerful electron-donating substituents, e.g. methoxyl or dimethylamino, ortho or para (but not meta) to the NH group. An examination of these phenomena leads to the conclusion that such long-range coupling provides evidence that intramolecular hydrogen bonding occurs between the NH and the 2-nitro groups. N-Benzyl-2,4-dinitroaniline also exhibited similar long-range coupling but, in dimethyl sulphoxide solut'ion, this coupling was temperature-dependent. The chemical shift data of the ortho-nitrodiphenylamines suggest that they adopt a non-planar skew conformation in solution.

A six-bond H-F coupling was observed between the fluorine atom and the 6-proton of 2'-fluoro-2,4-dinitrodiphenylamine.

https://doi.org/10.1071/CH9722145c

© CSIRO 1972

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