Isomerization of Cyclopropene to Allene and Propyne at Elevated Temperatures. Experimental, ab Initio, and Model Calculations

Article abstract of DOI:10.1021/j100335a017

Results of an experimental and theoretical investigation of the isomerization of cyclopropene to propyne and allene are reported.Shock tube experiments were carried out over the temperature range 800-1200 K, and ratios of / at different temperatures and pressures were measured.Ab initio calculations were done, from which energy levels and vibrational frequencies of two transition states were evaluated.RRKM and absolute rate theory calculations based on these parameters produced the following high-pressure rate coefficients (at 800 K): k₁=10^13.42exp(-65.1x10³/RT) s^-1, k₂=10^13.85exp(-43.7x10³/RT) s^-1, k₃=10^14.03exp(-70.8x10³/RT) s^-1, and k₄=10^14.18exp(-50.4x10³/RT) s^-1, where R is expressed in units of cal/(K mol).RRKM calculated rate coefficients were used to compute ratios of / at different temperatures and pressures and to compare them with the experimental results.A very good agreement between experiment and theory is obtained.