Computational studies on the gas phase reaction of methylenimine (CH2NH) with water molecules

Abstract

gas phase reaction ≤ 500 K, but the rate of formation of formaldehyde and ammonia is predicted to be negligibly slow. This result is also consistent with previous studies on the similar reaction system, i.e., H 2 O + H 2 C=C=O. Experimental studies are required to understand the formation of CH 2 O and NH 3 from CH 2 NH + H 2 O, and other formation schemes must be explored. Once the laboratory characterization is complete, CH 2 O and NH 3 will be an ideal target for observational search. Although this is an interesting reaction system, our results demonstrate that CH 2 NH + H 2 O is not important under atmospheric and combustion conditions compared to an important radical molecule reaction. Such results are encouraging, and chemical kinetic mechanism can be useful for the future implementation of hydrolysis of other imine compounds.

Effect of ammonia and water molecule on OH + CH3OH reaction under tropospheric condition

“…The rate coefficients for the formation of CH 3 OH···HO is almost independent of temperature. The calculated value is also compared with similar type of reaction system and the values were very close to each other 16 , 26 . The calculated lifetime of the complex at 225 K, which is near to the altitude of 10–12 km is ~ 1 ns.…”

“…We have applied a similar approach for the water-assisted reactions as discussed in the case of ammonia and earlier studies 16 – 26 . Because the simultaneous collisions of OH, CH 3 OH and H 2 O, are very unlikely, the termolecular reaction probability is very small under true conditions either a CH 3 OH···H 2 O or OH···H 2 O is expected to form first, followed by an attack of the third molecule OH or CH 3 OH to this complex.…”

“…During the past few years, many research groups have proposed the catalytic effect of a single water molecule for many atmospheric reactions 11 – 26 . The possibility of one water molecule as a catalyst in reactions of OH + CH 3 OH, have been proposed by Jara et al 12 , 13 and Chao et al Chao et al 11 have measured reaction rate coefficients with water molecule and suggested that no catalytic role of water molecule was observed, which contradict the measurement of Jara-Toro et al 12 , 13 Recently, Wu et al 14 have proposed the detailed study of water-assisted pathways and predicted temperature-dependent rate coefficients for OH + CH 3 OH (+ H 2 O) using hybrid functional coupled with advanced kinetic models 14 .…”

Catalytic Effect of CO2 and H2O Molecules on •CH3 + 3O2 Reaction

“…The vibrational mode, which corresponds to the Hindered Rotor (HR), was treated as HR approximation in the densum-input file. To further improve the accuracy of energy, the single-point energy calculations were performed at CCSD(T)/6-311++G(3df,3pd) [designated CC-p] level [28][29][30][31][32][33]. The RCCSD(T) method was used for closed-shell species, such as CH 2 O and H 2 O, CO 2 , and for all open-shell species the UCCSD(T) method was used.…”

“…They also suggested that the chemical kinetic analysis for the effect of CO 2 on CH 3 + O 2 reaction is underway. Therefore, in this study, we have re-investigated the effect of CO 2 on the • CH 3 + 3 O 2 reaction using a similar level of theory in combination with an advanced statistical-rate theory, to understand the chemical kinetic behavior for the effect of CO [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36]. All of these studies indicate that a single H 2 O molecule makes complexes, transition states and post complexes thermodynamically more stable than a water free-reaction, due to the formation of more hydrogen-bonded species.…”