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Abstract

Single pulse shock tube studies of the thermal dehydrochlorination reactions (chlorocyclopentane [RIGHTWARDS ARROW] cyclopentene + HCl) and (chlorocyclohexane [RIGHTWARDS ARROW] cyclohexene + HCl) at temperatures of 843–1021 K and pressures of 1.4–2.4 bar have been carried out using the comparative rate technique. Rate constants have been measured relative to (2-chloropropane [RIGHTWARDS ARROW] propene + HCl) and the decyclization reactions of cyclohexene, 4-methylcyclohexene, and 4-vinylcyclohexene. Absolute rate constants have been derived using k(cyclohexene [RIGHTWARDS ARROW] ethene + butadiene) = 1.4 × 1015 exp(−33,500/T) s−1. These data provide a self-consistent temperature scale of use in the comparison of chemical systems studied with different temperature standards. A combined analysis of the present results with the literature data from lower temperature static studies leads to

  • k(2-chloropropane) = 10(13.98±0.08) exp(−26, 225 ± 130) K/T) s−1; 590–1020 K; 1–3 bar

  • k(chlorocylopentane) = 10(13.65 ± 0.10) exp(−24,570 ± 160) K/T) s−1; 590–1020 K; 1–3 bar

  • k(chlorocylohexane) = 10(14.33 ± 0.10) exp(−25,950 ± 180) K/T) s−1; 590–1020 K; 1–3 bar

Including systematic uncertainties, expanded standard uncertainties are estimated to be about 15% near 600 K rising to about 25% at 1000 K. At 2 bar and 1000 K, the reactions are only slightly under their high-pressure limits, but falloff effects rapidly become significant at higher temperatures. On the basis of computational studies and Rice–Ramsperger–Kassel–Marcus (RRKM)/Master Equation modeling of these and reference dehydrochlorination reactions, reported in more detail in an accompanying article, the following high-pressure limits have been derived:

  • k (2-chloropropane) = 5.74 × 109T1.37 exp(−25,680/T) s−1; 600–1600 K

  • k (chlorocylopentane) = 7.65 × 107T1.75 exp(−23,320/T) s−1; 600–1600 K

  • k (chlorocylohexane) = 8.25 × 109T1.34 exp(−25,010/T) s−1; 600–1600 K

© 2011 Wiley Periodicals, Inc.* Int J Chem Kinet 44: 351–368, 2012