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 (CH3CCH) 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 + CH3CCH CHCH(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 + CH3CCH CH2=C=CH2(Allene) + H) and k (H + CH3CCH CHC-CH2(Propargyl) + H2).

The present data are compared with relevant previous work.

 

Author’s Information:

Claudette M. Rosado-Reyes

Mentor: Jeffrey A. Manion

Physical and Chemical Properties Division (838.06)

Chemical Science and Technology Laboratory

Bldg.221/A167

Mail Stop 8380

301-975-2559 office

301-869-4020 fax

claudette.rosado-reyes@nist.gov

Category: Chemistry