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Kinetics and mechanism of the thermal reactions of endo ‐ and exo ‐5‐cyanobicyclo[2.2.2]oct‐2‐ene and methyl‐substituted derivatives in the gas phase
Author(s) -
Van Mele B.,
Huybrechts G.
Publication year - 1987
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.550191002
Subject(s) - chemistry , kinetics , kinetic energy , ene reaction , gas phase , reaction mechanism , activation energy , bicyclic molecule , photochemistry , thermal , medicinal chemistry , computational chemistry , thermodynamics , organic chemistry , catalysis , physics , quantum mechanics
The thermal reactions of endo ‐ and exo ‐5‐cyanobicyclo‐[2.2.2]oct‐2‐ene and their trans ‐ and cis ‐6‐methyl‐substituted derivatives have been investigated in the gas phase between 518 and 630 K. Each product decomposes by two parallel first‐order retro‐Diels‐Alder reactions, a main one with formation of cyclohexa‐1,3‐diene and a minor one with elimination of ethene. Slight isomerizations are also observed. The kinetic results can be explained in terms of a biradical mechanism. The rate‐determining step is shown to depend on the amount of resonance energy in the biradical. Heats of formation and entropies of the bicyclo[2.2.2]oct‐2‐enes studied are estimated.