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Kinetics of the cyclopentadiene decay and the recombination of cyclopentadienyl radicals with H‐atoms: Enthalpy of formation of the cyclopentadienyl radical
Author(s) -
Roy K.,
BraunUnkhoff M.,
Frank P.,
Just Th.
Publication year - 2001
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.10005
Subject(s) - cyclopentadienyl complex , chemistry , enthalpy , cyclopentadiene , atmospheric temperature range , thermochemistry , standard enthalpy of formation , radical , dissociation (chemistry) , bond dissociation energy , thermodynamics , organic chemistry , catalysis , physics
Abstract The recombination of c‐C 5 H 5 with H‐atoms has been studied behind reflected shock waves. The obtained rate coefficients are almost independent of temperature and were found to be k rec = 2.6 × 10 14 cm 3 mol −1 s −1 for pressures around 2 bar in the temperature range between 1150 and 1500 K. Together with rate coefficients for the dissociation, obtained in an earlier work (Roy et al., Proc Combust Inst 1998, 27, 329–336) at pressures and temperatures close to those applied in the present work, we calculated equilibrium constants K c ( T ) for C 5 H 6 ⇌ c‐C 5 H 5 + H. A “third law” analysis was performed. Data for the enthalpy of formation of cyclopentadienyl DH f,0 = 65.4 ± 1 kcal mol −1 and DH f,298 = 62.5 ± 1 kcal mol −1 were derived, respectively. The analysis was based upon new results on the entropy of cyclopentadienyl, recently calculated by Kiefer et al. (J phy chem, in press). Finally, our measured data were subjected to a fall‐off analysis. The simulation turned out very satisfactorily. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 33: 821–833, 2001