Enazine chemistry II. The mechanism of formation of 1‐( cis ‐3‐phenylpropenyl)‐5‐phenylpyrazole from the pyrolysis of cinnamaldehyde azine | Zendy

Stern Robert L. | Zendy; Krause Josef G. | Zendy

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Enazine chemistry II. The mechanism of formation of 1‐( cis ‐3‐phenylpropenyl)‐5‐phenylpyrazole from the pyrolysis of cinnamaldehyde azine

Author(s) -

Stern Robert L.,

Krause Josef G.

Publication year - 1968

Publication title -

journal of heterocyclic chemistry

Language(s) - English

Resource type - Journals

SCImago Journal Rank - 0.321

H-Index - 59

eISSN - 1943-5193

pISSN - 0022-152X

DOI - 10.1002/jhet.5570050220

Subject(s) - chemistry , cinnamaldehyde , intramolecular force , azine , kinetic isotope effect , hydrogen atom abstraction , reaction mechanism , computational chemistry , photochemistry , pyrolysis , kinetic energy , medicinal chemistry , organic chemistry , hydrogen , deuterium , catalysis , physics , quantum mechanics

The mechanism of pyrazole formation from the thermolysis of α,β‐unsaturated azines has been examined by both kinetic and non‐kinetic methods. The reaction exhibits a large negative entropy of activation, a large primary isotope effect and a positive slope in a Hammett study on cinnamaldehyde derivatives. The reaction was shown to be cleanly intramolecular and was also unaffected by radical traps. A mechanism involving intramolecular 1‐5 abstraction of a proton is presented, which accounts for all of the experimental data.

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