Abstract
The kinetics of C~6~H~5~ reactions with n‐C~n~H~2__n__+2~ (n = 3, 4, 6, 8) have been studied by the pulsed laser photolysis/mass spectrometric method using C~6~H~5~COCH~3~ as the phenyl precursor at temperatures between 494 and 1051 K. The rate constants were determined by kinetic modeling of the absolute yields of C~6~H~6~ at each temperature. Another major product C~6~H~5~CH~3~ formed by the recombination of C~6~H~5~ and CH~3~ could also be quantitatively modeled using the known rate constant for the reaction. A weighted least‐squares analysis of the four sets of data gave k (C~3~H~8~) = (1.96 ± 0.15) × 10^11^ exp[−(1938 ± 56)/T], and k (n‐C~4~H~10~) = (2.65 ± 0.23) × 10^11^ exp[−(1950 ± 55)/T] k (n‐C~6~H~14~) = (4.56 ± 0.21) × 10^11^ exp[−(1735 ± 55)/T], and k (n−C~8~H~18~) = (4.31 ± 0.39) × 10^11^ exp[−(1415 ± 65)T] cm^3^ mol^−1^ s^−1^ for the temperature range studied. For the butane and hexane reactions, we have also applied the CRDS technique to extend our temperature range down to 297 K; the results obtained by the decay of C~6~H~5~ with CRDS agree fully with those determined by absolute product yield measurements with PLP/MS. Weighted least‐squares analyses of these two sets of data gave rise to k (n−C~4~H~10~) = (2.70 ± 0.15) × 10^11^ exp[−(1880 ± 127)/T] and k (n−C~6~H~14~) = (4.81 ± 0.30) × 10^11^ exp[−(1780 ± 133)/T] cm^3^ mol^−1^ s^−1^ for the temperature range 297‐‐1046 K. From the absolute rate constants for the two larger molecular reactions (C~6~H~5~ + n‐C~6~H~14~ and n‐C~8~H~18~), we derived the rate constant for H‐abstraction from a secondary CH bond, k~s−CH~ = (4.19 ± 0.24) × 10^10^ exp[−(1770 ± 48)/T] cm^3^ mol^−1^ s^−1^. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 36: 49–56, 2004