Pyrolysis of 2,4-dimethylhexene-l and the stability of isobutenyl radicals

✍ Scribed by Wing Tsang

• Publisher: John Wiley and Sons
• Year: 1973
• Tongue: English
• Weight: 806 KB
• Volume: 5
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.550050604

✦ Synopsis

Abstract

2,4‐Dimethylhexene‐l has been decomposed in single‐pulse shock tube experiments. Rate expressions for the initial reactions are
and
sec^−1^ at 1.5–5 atm and 1050°K. This leads to Δ__H__^°^~f300~ (CH~2~ = C(CH~3~)CH~2~) = 124 kJ/mol, or an allylic resonance energy of 50 kJ/mol. Rate expressions for the decomposition of the appropriate olefins which yield isobutenyl radicals and methyl, ethyl, isopropyl, n‐propyl, t‐butyl, and t‐amyl radicals, respectively, are presented. The rate expression for the decomposition of isobutenyl radical is
(at the beginning of the fall‐off region). For the combination of isobutenyl and methyl radicals, the rate constant at 1020°K is
Combination of this number and the calculated rate expression for 2‐methylbutene‐1 decomposition gives S. (1100) = 470 J/mol °K. This yields
It is demonstrated that an upper limit for the rate of hydrogen abstraction by isobutenyl from toluene is