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4-Isopropylidene-3,3,5,5-tetramethyl-Δ1-pyrazoline - an almost flat pyrazoline

✍ Scribed by Richard J. Bushby; Stephen Mann; Walter S. McDonald

Publisher
Elsevier Science
Year
1982
Tongue
French
Weight
181 KB
Volume
23
Category
Article
ISSN
0040-4039

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✦ Synopsis

The X-ray crystallographic structure of the title compound _6_ shows that it is almost planar. This helps to explain a number of peculiar features in the chemistry of a-methylated pyrazolines. The rate of thermal deazetation of azoalkanes R-N=N-R normally depends on the stability of the alkyl radicals produced. 1 In the case of Al-pyrazolineAthe introduction of a radical stabilising alkylidene substituent in the 4-position (as in compound 2-1 lowers the energy barrier to nitrogen loss by ca. 10 kcal/mol and a similar effect is observe3 in the case of the bicyclic pyrazolines 2 and 4. 2

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