ISSN:
0538-8066
Keywords:
Chemistry
;
Physical Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The kinetics of the reversible recombination of the 2-phenyl- (I), 2-p-methoxyphenyl-(II), and 2-p-nitrophenyl-3-oxo-2,3-dihydrobenzothiophene-2-yl (III) radicals have been investigated. Recombination rate constants of R(I-III) have been determined in different solvents (2k1 ∼ 109 M-1 s-1). The rate of reaction (I) with R(I-III) decreases with increasing solvent viscosity η. In the toluene-vaseline oil mixture (2 ≲ η ≲ 120 cP) the recombination of R(I-III) is molecular mobility limited. The thermodynamic parameters of reaction (I) have been determined: ΔH0 = 20-30 kcal/mol. Activation volumes ΔV1≠ for recombination of R(II) have been measured. In n-propanol ΔV1≠ is equal to the viscous flow activation volume of the solvent ΔVd≠. In toluene and chloroform ΔV1≠ 〈 ΔVd≠. For the last two solvents the activation volumes of the cage reaction have been estimated ΔV1≠(r) = -(2-3) cm3/mol. Visible-range absorption spectra and ESR spectra have been recorded for R(I-III). The role of cage effect in the reactivity anisotropy averaging of R(I-III) is discussed. The potential of the high-pressure tests for deriving information about the elementary act of a fast bimolecular reaction is considered.
Additional Material:
5 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/kin.550170704
Permalink
