An ab initio/Rice-Ramsperger-Kassel-Marcus prediction of rate constant and product branching ratios for unimolecular decomposition of propen-2-ol and related H + CH2COHCH2 reaction.
Enols have been found to be important intermediates in the combustion flames of hydrocarbon [C. A. Taatjes et al., Science 308, 1887 (2005)]. The removal mechanism of enols in combustion flame has not been established yet. In this work, the potential energy surface for the unimolecular decomposition of syn-propen-2-ol and H + CH(2)COHCH(2) recombination reactions have been first investigated by CCSD(T) method. The barrier heights, reaction energies, and geometrical parameters of the reactants, products, intermediates, and transition states have been investigated theoretically. The results show that the formation of CH(3)CO + CH(3) via the CH(3)COCH(3) intermediate is dominant for the unimolecular decomposition of syn-propen-2-ol and its branching ratio is over 99% in the whole temperature range from 700 to 3000 K, and its rate constant can be expressed as an analytical form in the range of T=700-3000 K at atmospheric pressure. This can be attributed to the lower energy barrier of this channel compared to the other channels. The association reaction of H with CH(2)COHCH(2) is shown to be a little more complicated than the unimolecular decomposition of syn-propen-2-ol. The channel leading to CH(3)CO + CH(3) takes a key role in the whole temperature range at atmospheric pressure. However at the higher pressure of 100 atm, the recombination by direct formation of syn-propen-2-ol through H addition is important at T<1000 K. In the range of T>1400 K, the recombination channel leading to CH(3)CO + CH(3) turns out to be significant.
Zhou
Chong-Wen
CW
College of Chemical Engineering, Sichuan University, Chengdu, 610065, People's Republic of China.
Li
Ze-Rong
ZR
Liu
Cun-Xi
CX
Li
Xiang-Yuan
XY