Thermal decomposition of 1‐butyne in shock waves

1‐Butyne diluted with Ar was heated behind reflected shock waves over the temperature range of 1100–1600 K and the total density range of 1.36 × 10 −5 −1.75 × 10 −5 mol/cm 3 . Reaction products were analyzed by gas‐chromatography. The progress of the reaction was followed by IR laser kinetic absorption spectroscopy. The products were CH 4 , C 2 H 2 , C 2 H 4 , C 2 H 6 , allene, propyne, C 4 H 2 , vinylacetyiene, 1,2‐ butadiene, 1,3‐butadiene, and benzene. The present data were successfully modeled with a 80 reaction mechanism. 1‐Butyne was found to isomerize to 1,2‐butadiene. The initial decomposition was dominated by 1‐butyne → C 3 H 3 + CH 3 under these conditions. Rate constant expressions were derived for the decomposition to be k 7 = 3.0 × 10 15 exp(−75800 cal/ RT ) s −1 and for the isomerization to be k 4 = 2.5 × 10 13 exp(−65000 cal/ RT ) s −1 . The activation energy 75.8 kcal/mol was cited from literature value and the activation energy 65 kcal/mol was assumed. These rate constant expressions are applicable under the present experimental conditions, 1100–1600 K and 1.23–2.30 atm. © 1995 John Wiley & Sons, Inc.