Theoretical study of reaction of ketene with water in the gas phase: formation of acetic acid?

Production of acetic acid via gas-phase hydration of ketene by water (uncatalyzed and in the presence of an additional water molecule) was theoretically characterized using high-level coupled-cluster methods, followed by a two-dimensional master equation analysis to compute thermal reaction rate constants. The results show that the formation of acetic acid quite likely occurs in high-temperature combustion of biomass, but that the rate of formation should be negligible under ambient atmospheric conditions.

Reaction of HO with CO: Tunneling Is Indeed Important.

The potential energy surface and chemical kinetics for the reaction of HO with CO, which is an important process in both combustion and atmospheric chemistry, were computed using high-level ab initio quantum chemistry in conjunction with semiclassical transition state theory under the limiting cases of high and zero pressure. The reaction rate constants calculated from first principles agree extremely well with all available experimental data, which range in temperature over a domain that covers both combustion and terrestrial atmospheric chemistry. The role of quantum tunneling is confirmed to be extremely important, which supports recent work by Continetti and collaborators regarding the loss of hydrogen atoms from vibrationally excited states of HOCO. A sensitivity analysis has been carried out and serves as the basis for a plausible estimate of uncertainty in the calculations.