Unveiling the chemical kinetics of aminomethanol (NHCHOH): insights into H and O photo-oxidation reactions and formamide dominance.

Aminomethanol is released into the atmosphere through various sources, including biomass burning. In this study, we have expounded the chemical kinetics of aminomethanol in the reaction pathways initiated by the hydroxyl radical ( H) with the aid of //density functional theory (DFT) , coupled-cluster theory (CCSD(T))//hybrid-DFT (M06-2X/6-311++G (3df, 3pd). We have explored various possible directions of the H radical on aminomethanol, as well as the formation of distinct pre-reactive complexes. Our computational findings reveal that the H transfer necessitates activation energies ranging from 4.1 to 6.5 kcal/mol from the -CH group, 3.5-6.5 kcal/mol from the -NH group and 7-9.3 kcal/mol from the -OH group of three rotational conformers. The H transfer from -CH, -NH and -OH exhibits an estimated total rate constant ( ) of approximately 1.97 × 10 cm molecule s at 300 K. The branching fraction analysis indicates a pronounced dominance of C-centered NH HOH radicals with a favorability of 77%, surpassing the N-centered HCHOH (20%) and O-centered NHCH (3%) radicals. Moreover, our investigation delves into the oxidation of the prominently favored carbon-centered NH HOH radical through its interaction with atmospheric oxygen molecules. Intriguingly, our findings reveal that formamide (NHCHO) emerges as the predominant product in the NH HOH + O reaction, eclipsing alternative outcomes such as amino formic acid (NHCOOH) and formimidic acid (HN = C(H)-OH). At atmospheric conditions pertinent to the troposphere, the branching fraction value for the formation of formamide is about 99%, coupled with a rate constant of 5.5 × 10 cm molecule s. Finally, we have scrutinized the detrimental impact of formamide on the atmosphere. Interaction of formamide with atmospheric hydroxyl radicals could give rise to the production of potentially perilous compounds such as HNCO. Further, unreacted HCHOH radicals may initiate the formation of carcinogenic nitrosamines when reacting with trace N-oxides (namely, NO and NO). This, in turn, escalates the environmental risk factors.