Kinetics and mechanism of the addition of 1,3‐butadiene to cyclohexa‐1,3‐diene in the gas phase

Abstract

The thermal reactions of 1,3-butadiene (BD) with cyclohexa-1,3-diene (CHD) have been studied in a static system between 437 and 526 K. The pressures of BD and CHD were varied from 61 to 397 torr and from 50 to 93 torr, respectively. The percentages of consumed BD and CHD were always kept lower than 14%. The reactions-in the order of importanceare A thermochemical analysis of a biradical mechanism is in agreement with these results.

Kinetics of the thermal reactions of bicyclo[4.2.2]deca‐3,7‐diene and endo‐and exo‐5‐vinylbicyclo[2.2.2]oct‐2‐ene in the gas phase

“…For the case where K, = exo-VHO, these concentrations were corrected for the reactions ( 2 ) of the less stable endo-VRO formed and for the reactions (1) of BDI) which is shown to be an important, but unstable, intermediate (see discussion).…”

“…They are all first order, and their rates are not influenced by the surface-to-volume ratio of the reaction cell. The temperature ranges were almost the same as that for the study of the addition of BD to CHD (437-526 K) [2]. The reaction (15) endo-VBO ___+ exo-VBO…”

“…HHN and BDD were better than 99.9% pure. BD and CHD were as in [2] and [4], respectively. Endo-and exo-VBO [5,6], HHN, and BDD were identified from their nuclear magnetic resonance, mass, and infrared spectra.…”

“…The heats of formation and the entropies of endo-VBO, exo-VBO, and BDD are estimated. [1,2]. A study of the reactions of endo-and exo-VBO and BDD is reported in this paper.…”

ChemInform Abstract: 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

“…They also suggest that the position of the rate-determining transition state depends on the amount of stabilizing energy in the concerned biradicals. Indeed, it would lie between (i) the cycloadduct and the biradical when the biradical is only stabilized by the ally1 resonance in the ring (BO [21 and alkyl-substituted derivatives [1,5,14,16] and ethene elimination in this work) and (ii) the biradical and diene and dienophile when it is further stabilized by the resonance energy of a substituent (cyano-and vinyl-substituted BOs [3,6,13, and CHD elimination in this work] and dimers of CHD [151).…”