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Self‐ and cross‐disproportionation‐to‐combination rations for cyclopentyl and cyclohexyl radicals and their deuterated analogues
Author(s) -
Fujisaki Noboru,
Gäumann Tino
Publication year - 1982
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.550141002
Subject(s) - disproportionation , chemistry , neopentane , radical , deuterium , hydrogen , cycloalkene , radiolysis , reaction rate constant , medicinal chemistry , stereochemistry , kinetics , molecule , hydrocarbon , organic chemistry , catalysis , physics , quantum mechanics
Hydrogen, cycloalkene, and bicycloalkyl were found to be the principal products which account for ≈97% of all products formed in the gas‐phase radiolysis of water vapor containing low concentrations of cycloalkanes. From the ratios of cycloalkene‐to‐bicycloalkyl yields extrapolated to the zero dose, the self‐ and cross‐disproportionation‐to‐recombination rate constant ratios Δ = k d /k c were determined for the following 12 reactions: Δ( c ‐C 5 H 9 , c ‐C 5 H 9 ) = 0.73; Δ( c ‐C 5 D 9 , c ‐C 5 D 9 ) = 0.58; Δ( c ‐C 6 H 11 , c C 6 H 11 ) = 0.59; Δ( c ‐C 6 D 11 , c ‐C 6 D 11 ) = 0.46; Δ( c ‐C 5 H 9 , c ‐C 6 H 11 ) = 0.28; Δ( c ‐C 5 D 9 , c ‐C 6 H 11 ) = 0.28; Δ( c ‐C 5 H 9 , c ‐C 6 D 11 ) = 0.24; Δ( c ‐C 5 D 9 , c ‐C 6 D 11 ) = 0.24; Δ( c ‐C 6 H 11 , c ‐C 5 H 9 ) = 0.33; Δ( c ‐C 6 H 11 , c ‐C 5 D 9 ) = 0.25; Δ( c ‐C 6 D 11 , c ‐C 5 H 9 ) = 0.35; and Δ( c ‐C 6 D 11 , c ‐C 5 D 9 ) = 0.28, where in the case of the cross‐disproportionation the symbol Δ(R 1 ,R 2 ) is used to represent k d /k c for the disproportionation in which radical R 1 captures a hydrogen (deuterium) atom from radial R 2 . The geometrical mean rule holds in the cross‐combination reactions of cyclopentyl and cyclohexyl radicals. The kinetic isotope effect in the disproportionation reaction was determined as 1.24 ± 0.06.