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NMR studies of hindered rotation and thermal decomposition of novel 1‐aryl‐3,3‐dialkyltriazenes
Author(s) -
Lippert Th.,
Wokaun A.,
Dauth J.,
Nuyken O.
Publication year - 1992
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1260301206
Subject(s) - chemistry , steric effects , aryl , thermal decomposition , differential scanning calorimetry , molecule , aniline , computational chemistry , carbon 13 nmr , medicinal chemistry , stereochemistry , crystallography , organic chemistry , thermodynamics , alkyl , physics
Abstract 1‐Aryl‐3,3‐dialkyltriazenes have been synthesized by coupling the corresponding diazonium salts of substituted aniline derivatives with dialkylamines. The thermostability of these compounds was investigated by differential scanning calorimetry; activation energies of 240–280 kJ mol −1 were determined for the thermal decomposition. The hindered rotation of the dialkylamino group was studied by 1 H NMR exchange measurements. Both experiments are interpreted in terms of an involvement of a 1,3‐dipolar structure of the NNN functional group. The influence of substituents, both on the aromatic ring and at the amino group, on the kinetic and activation parameters is investigated; results are analysed on the basis of mesomeric and steric effects on the dipolar charge distribution in the molecule.