Quantum Mechanical Investigation of the Atmospheric Reaction CH₃O₂ + NO

Abstract

The important stationary points on the potential energy surface of the reaction CH(3)O(2) + NO have been investigated using ab initio and density functional theory techniques. The optimizations were carried out at the B3LYP/6-311++G(d,p) and MP2/6-311++G(d,p) levels of theory while the energetics have been refined using the G2MP2, G3//B3LYP, and CCSD(T) methodologies. The calculations allow the proper characterization of the transition state barriers that determine the fate of the nascent association conformeric minima of methyl peroxynitrite. The main products, CH(3)O + NO(2), are formed through either rearrangement of the trans-conformer to methyl nitrate and its subsequent dissociation or via the breaking of the peroxy bond of the cis-conformer to CH(3)O + NO(2) radical pair. The important consequences of the proposed mechanism are (a) the allowance on energetic grounds for nitrate formation parallel to radical propagation under favorable external conditions and (b) the confirmation of the conformational preference of the homolytic cleavage of the peroxy bond, discussed in previous literature.

Sensitizing effects of NOx on CH4 oxidation at high pressure

“…No rate measurements have been reported above ∼400 K, whereas numerous investigations are available at low temperatures relevant to atmospheric chemistry research. Recent ab initio calculations of the potential energy surface of NO + CH 3 OO by Zhao et al [104] and Lesar et al [105] have confirmed that the reaction follows an addition/elimination mechanism through the intermediate adduct CH 3 OONO * followed either by direct cleavage of the peroxy bond or rearrangement to CH 3 ONO * 2 before breakage to NO 2 + CH 3 O. The reaction involving C 2 H 5 OO is expected to follow an analogous mechanism.…”

Global exploration of isomers and isomerization channels on the quantum chemical potential energy surface of H3CNO3

“…This article describes a study on the exploration of isomers, isomerization reactions, as well as their reaction routes for H 3 CNO 3 using SHS‐ADDF. Studies on H 3 CNO 3 were reported recently in relation to combustion and atmospheric chemistry . The reaction channels for some isomers of H 3 CNO 3 including nitromethanol (HOCH 2 NO 2 ) and nitrosooxymethnol (HOCH 2 ONO) were elucidated using hybrid density‐functional‐theory (DFT) B3LYP method in connection with radical‐molecule reaction of CH 2 OH with NO 2 .…”

“…The reaction channels for some isomers of H 3 CNO 3 including nitromethanol (HOCH 2 NO 2 ) and nitrosooxymethnol (HOCH 2 ONO) were elucidated using hybrid density‐functional‐theory (DFT) B3LYP method in connection with radical‐molecule reaction of CH 2 OH with NO 2 . The reaction channels involving methyl nitrate (H 3 CONO 2 ) and methyl peroxynitrite (H 3 COONO) related to atmospheric systems were studied in different levels of calculations . We assumed that interesting chemistry would be discovered more from the GRRM for H 3 CNO 3 because of its potential of the formation of various functional groups, including OH, OO, OOH, OOO, CO, CHO, COOH, COOOH, CN, NH, NH 2 , NO, NO 2 , NO 3 , NOO, ONO, NOH, NOOH, NHOH, CH, CH 2 , and CH 3 , which can compose various chemical structures.…”

Computational study of the perhalogenated methyl nitrates CX3ONO2, CXxY3−xONO2(X, Y = F, Cl)

“…The comparison to the corresponding theoretical data for CH 3 ONO 2 [32] demonstrates the significant geometrical changes caused upon substitution of the methylic hydrogens by chlorine and fluorine atoms. Comparison is also made with recent experimental and theoretical findings for CF 3 ONO 2 [33], which shows a good overall agreement between the present theoretical results and the literature data for the perfluorinated methyl nitrate.…”

“…The computational modeling of the nitrate formation channel has also been the subject of many theoretical efforts focused primarily on the simplest system CH 3 O 2 +NO. In all theoretical investigations, the mechanism of the reaction was found to involve the formation of both conformers of the nascent association methylperoxy nitrite adduct [26][27][28][29][30][31][32]. The two distinct conformeric structures have been characterized with respect to the ONOO dihedral angle as the cis-perp and the trans-perp configurations, where the perp notation refers to the nearly perpendicular geometry of the carbon atom of the attached methyl group.…”