Kinetics and mechanisms of the reaction of acetylene with cyclohexa-1,3-diene and the decomposition of bicyclo[2.2.2]-octa-2,5-diene in the gas phase

✍ Scribed by G. Huybrechts; W. Leemans; B. Van Mele

• Publisher: John Wiley and Sons
• Year: 1982
• Tongue: English
• Weight: 386 KB
• Volume: 14
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.550140905

✦ Synopsis

Abstract

The reaction of acetylene (A) with cyclohexa‐1,3‐diene (CHD) has been studied between 450 and 592 K. The pressures of A ranged from 25 to 112 torr and those of CHD from 8 to 62 torr. The reaction yields only ethene (E) and benzene (B) instead of bicyclo[2.2.2]octa‐2,5‐diene (BOD), the product that is expected for a 1,4,1′,2′ addition of the Diels–Alder type. It is first order with respect to each reagent. The rate constant (in L/mol·s) is given by
The thermal decomposition of BOD has also been studied. In the ranges of 354–435 K and 0.5–6 torr, the reaction is first order and results in the formation of equal amounts of B and E as the reaction of A with CHD does. Its rate constant (in s^−1^) is given by
The following consecutive reactions are proposed for the reaction between A and CHD: magnified image where BOD is the primary product that is too unstable to be detected. This implies that the rate constant k is equal to k~a~. The reaction mechanisms and the strain energy in BOD are discussed.