Journal of Physical Chemistry A vol:103 issue:28 pages:5523-5533
We present a detailed microvariational RRKM Master Equation analysis of the CH(X(2)Pi) + C2H2 reaction products distribution, based on an earlier quantum chemical characterization of the accessible potential energy surface. This is the first time that the pressure and temperature dependence of the product distribution has been analyzed and discussed. Also, an extensive error analysis is performed, aiming to quantify the confidence region for the predicted product distribution as a function of temperature and pressure. The results indicate that for pressures up to several atmospheres, H + triplet prop-2-enylidene (HCCCH) and H + singlet cyclopropenylidene (cyc-C3H2) are the main reaction products, with smaller contributions from C3H + H-2 formation. Typical net yields are 90% HCCCH, 7% CYC-C3H2 at 300 K and 82% HCCCH, 11% cyc-C3H2 at 2000 K, for pressures from 0 to 5 atm. Substantial stabilization of 2-propynyl radicals (H2CCCH) occurs only at higher pressures in excess of 10 atm of air. Our results disagree with another recent theoretical study, which did not consider several of the most important entrance and exit channels.