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Investigations of intramolecular hydrogen bonding in three types of Schiff bases by 2H and 3H NMR isotope effects

✍ Scribed by Wojciech Schilf; James P. Bloxsidge; John R. Jones; Shui-Yu Lu

Publisher
John Wiley and Sons
Year
2004
Tongue
English
Weight
131 KB
Volume
42
Category
Article
ISSN
0749-1581

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✦ Synopsis

Abstract

Hydrogen bonding within the structures of three Schiff bases (1–3), obtained by condensation of 4‐methoxy‐, 5‐methoxy‐ and 4,6‐dimethoxysalicylaldehyde with methylamine, was investigated by measuring deuterium and tritium NMR isotope effects. The primary deuterium and tritium isotope effects (δ~XH~−δ~XD/T~) and secondary one‐bond nitrogen deuterium effect appear to be very useful parameters for defining the character of intramolecular hydrogen bonds. The tritium isotope effects were also determined for nitrogen–hydrogen one‐bond coupling constants for both 4‐methoxy and 4,6‐dimethoxy derivatives. These parameters are seen to be highly sensitive to hydrogen bond characteristics and can be used to distinguish localized and tautomeric hydrogen bonds. Copyright © 2004 John Wiley & Sons, Ltd.

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