KINETICS OF THE THERMAL REACTION OF H ATOMS AND PROPYNE
Claudette M. Rosado-Reyes*, Jeffrey A. Manion, and Wing Tsang
The reaction of hydrogen atoms with propyne (CH3C≡CH) has been investigated in a heated single pulse shock tube at temperatures of 800-915K and pressures of 2-3 bar. Stable products from various reaction channels (terminal and non-terminal H addition, and H abstraction) have been identified and quantified by gas chromatography and mass spectrometry. The rate constant for the channel involving the displacement of methyl radical from propyne (non-terminal H addition) was determined relative to the methyl displacement from 1,3,5-trimethylbenzene (135TMB), with k (H + 135TMB → m-xylene + CH3) = 6.7 ´ 1013 exp(-3255/T) cm3/mole·s,
k (H + CH3C≡CH → CH≡CH(Acetylene)
+ CH3) = 6.9 ´ 1013 exp(-2839/T) cm3/mole·s
Preliminary results show that the branching ratio of non-terminal versus terminal H atom addition is approximately 50% at 850K. A model of elementary reactions including all possible channels is being developed. By fitting this model to our experimental data, rate constants for the terminal H addition and H abstraction channels will be derived at the respective temperatures and pressures of this study, k (H + CH3C≡CH → CH2=C=CH2(Allene) + H) and k (H + CH3C≡CH → CH≡C-CH2(Propargyl) + H2).
The present data are compared with relevant previous work.
Claudette M. Rosado-Reyes
Mentor: Jeffrey A. Manion
Physical and Chemical Properties Division (838.06)
Chemical Science and Technology Laboratory
Mail Stop 8380