Theoretical Study on Gas Phase Reaction of CH2O+NH3: Formation of CH2O···NH3, NH2CH2OH, or CH2NH + H2O

The hydrogen transfer reaction of CH2O with NH3 is an important reaction in cold interstellar clouds, combustion and in organic chemistry. In this work, the stationary point on the PESs for CH2O+NH3 reaction was computed at CCSD(T)/6-311++G(3df,3pd)/M06-2X/6-311++G(3df,3pd) level and rate constants were computed using advanced kinetic models, including microcanonical variational transition state theory and Rice−Ramsperger−Kassel−Marcus (RRKM)/master equation (ME) techniques. Our result predicts that the CH2O+NH3 reaction forms collisionally thermalized CH2O···NH3 with respect to thermal unimolecular dissociation; and other products i.e., NH2CH2OH and CH2NH + H2O are negligible at a lower temperature. The calculated atmospheric lifetime of CH2O···NH3 is ~17 mins suggest that the CH2O···NH3 can react with other atmospheric species. The results also suggest that the formation of CH2NH and H2O from Strecker’s process is negligibly small under all the conditions studied here. Under the combustion condition, the formation of NH2CH2OH kinetically favourable. The decay rate of formaldehyde reaction with ammonia is 5.1×10-4 s-1 (at 1500K) suggest that NH2CH2OH will be formed from the combustion of biomass. The atmospheric lifetime of NH2CH2OH in presence of OH radical is ~ 4 days suggest that NH2CHOH can further react with other atmospheric species, which can lead to the formation of carcinogenic products such as nitrosamines acetamide, hydrocycnic acid, NH2 and CO2.