Kinetics of CN radical reactions with selected cycloalkanes: CN reactivity towards secondary CH bonds

T. Yu, D. L. Yang, Ming-Chang Lin*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

The kinetics of the reaction of CN radicals with four molecules containing only secondary CH bonds, cyclopropane (c-C3H6), cyclopentane (c-C5H10), cyclohexane (c-C6H12) and cyclooctane (c-C8H16), have been studied with the two-laser pump-probe laser photolysis/laser induced fluorescence technique in the temperature range 219 to 740 K. The rate constant for CN + c-C3H6 was found to increase monotonically with temperature. However, a small negative temperature dependene of the rate was observed for CN + c-C5H10, c-C6H12, and c-C8H16. The rate constants for these reactions can be effectively represented, in units of cm3/s, by kc-C3H6 = 1.26 × 10-15 T1.50 exp(174/T), kc-C5H10 = 10-9.76±0.06 exp(40±19/T), kc-C6H12 = 10-9.67±0.08 exp(69±12/T), and kc-C8H16 = 10-9.56±0.05 exp(73±13/T). The reactivity per secondary CH bond for c-C3H6 is significantly smaller than that for c-C5H10, c-C6H12, and c-C8H16, the latter three of which have essentially the same reactivity. This is primarily due to the significant differences between the CH bond strength in c-C3H6 and the other cyclocompounds. The small negative temperature dependences in the larger cycloalkanes observed here are attributed to long-range dipole-induced-dipole attractive interactions.

Original languageEnglish
Pages (from-to)449-453
Number of pages5
JournalChemical Physics
Volume162
Issue number2-3
DOIs
StatePublished - 15 May 1992

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