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The kinetics of the bimolecular sel‐reaction of t‐butyl radicals in solution. I. Termination rates
Author(s) -
Schuh HansHerbert,
Fischer Hanns
Publication year - 1978
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19780610620
Subject(s) - chemistry , radical , reaction rate constant , steric effects , kinetics , steric factor , diffusion , electron paramagnetic resonance , thermodynamics , solvent , atmospheric temperature range , isotropy , kinetic energy , organic chemistry , nuclear magnetic resonance , physics , quantum mechanics
Termination rate constants 2K t for the self‐reaction of t‐butyl radicals in twelve different solvents are determined as a function of temperature by kinetic electron spin resonance. In the entire range measured, 7. 10 7 < 2K t < 2 · 10 10 dm 3 mol −1 s −1 , they are well described by the von Smoluchowski equation for diffusion controlled reactions, using a spin statistical factor, a temperature and solvent independent, isotropic reaction diameter, and diffusion coefficients for t‐butyl estimated following empirical or semiempirical prescriptions. Methods for the prediction of diffusion coefficients are critically discussed, and rules for the estimation of termination rate constants of steric unhindered alkyl radicals are suggested.