Kinetics of reversible recombination of aromatic C-centered radicals

✍ Scribed by L. A. Margulis; I. V. Khudyakov; V. A. Kuzmin; A. I. Prokof'ev; A. I. Yasmenko; G. Smets

• Publisher: John Wiley and Sons
• Year: 1985
• Tongue: English
• Weight: 610 KB
• Volume: 17
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.550170704

✦ Synopsis

The kinetics of the reversible recombination of the 2-phenyl-(I), 2-p-methoxyphenyl-(111, and 2-p-nitrophenyl-3-oxo-2,3-dihydrobenzothiophene-2-y1 (111) radicals R + R ---' D (1) have been investigated. Recombination rate constants of R(1-111) have been determined in different solvents (2kl -lo9 M-' s-'). The rate of reaction (I) with R(1-111) decreases with increasing solvent viscosity r). In the toluene-Vaseline oil mixture (2 6 7) s 120 cP) the recombination of R(1-111) is molecular mobility limited. The thermodynamic parameters of reaction (I) have been determined: AH = 20-30 kcal/mol. Activation volumes AV? for recombination of R(I1) have been measured. In n-propanol AV? is equal to the viscous flow activation volume of the solvent AVZ. In toluene and chloroform AV: < AVZ. For the last two solvents the activation volumes of the cage reaction have been estimated AV:'.' = -(2-3) cm3/mol. Visible-range absorption spectra and ESR spectra have been recorded for R(1-111). The role of cage effect in the reactivity anisotropy averaging of R(1-111) is discussed. The potential of the highpressure tests for deriving information about the elementary act of a fast bimolecular reaction is considered.

2ki 2k -1