Single-pulse shock tube studies of hydrocarbon pyrolysis. Part 4.—Isomerization of allene to methylacetylene

Abstract

The isomerization of allene to methylacetylene has been studied in a single-pulse shock tube over the range 1440–1810 K and a first order rate constant of 3.02 × 10¹⁴ exp(–388 kJ mol^–1/RT) s^–1 has been obtained for the temperature range 1440–1700 K. Experiments with deuterated allenes, combined with the absence of side products, demonstrate that below 1700 K the mechanism is predominantly (> 95 %) molecular. RRKM calculations show that it is possible to generate the experimental rate constants using physically-realistic models and suggest a limiting high pressure rate constant of ∼1.6 × 10¹⁵ exp(–400 kJ mol^–1/RT) s^–1.