DFT calculations of the intermediate and transition state in the oxidation of NO by oxygen in the gas phase

Abstract

The B3LYP density functional method using the extended basis set 6-311++G(3df) was used to calculate the stationary points along the reaction coordinate 2NO + O 2 ® 2NO 2 . The results of the calculation were compared with the reported physicochemical characteristics of this reaction. The origin of the barrierless activation of the oxygen molecule and driving force for the spontaneous oxidation of NO were examined.In 1774, the English chemist, Joseph Priestly, carried out the reaction 3Cu + 8HNO 3 ® 3Cu(NO 3 ) 2 + 2NO + 4H 2 O and called the gaseous product, NO, "nitrous air." He also noted that "nitrous air" had the property of acquiring a brown color upon mixing with air. Thus, Priestly was the first to discover the oxidation of nitric oxide to give nitrogen dioxideThe molecular mechanism of this reaction remained a mystery for 230 years throughout the entire history of modern chemistry until Gadzhiev et al. [1] have recently come close to its complete explanation.Nitric oxide (NO) is an intermediate in the industrial production of nitric acid. This process involves two major steps: 1) the oxidation of ammonia to give nitric oxide (NO) and 2) the conversion of NO into nitric acid through the oxidation of NO to NO 2 . Trimolecular reaction (1) has second-order kinetics relative to NO and first-order kinetics relative to oxygen [2]. This reaction is one of the few reported cases, in which, up to 600 K, the rate not only does not increase but actually decreases [3], giving rise to a negative observed activation energy, which has been a topic for discussion for many years [1][2][3][4][5][6][7][8].The major scheme for the mechanism proposed for the anomalous temperature dependence of the rate of reaction (1) has rested on the assumption that only (NO) 2 dimers, the probability of formation of which decreases with increasing temperature, take part in the reaction [2, 3]:(2a) 2NO « (NO) 2 , 0040-5760/11/4702-0093

A proline mimetic for enantioselective aldol reaction: a quantum chemical study of a catalytic reaction with a sterically hindered l‐prolinamide derivative

“…Even qualitative estimation of energies was found to be correct . As a drawback, several examples had been reported where B3LYP and other density functionals resulted to qualitatively incorrect mechanistic prediction of even textbook reactions . In the present study, we verified that B3LYP/6‐31G(d) remains a reliable theory level by BSSE evaluation and inclusion of correlation effects not covered by the hybrid GGA approach.…”

Theoretical study of the triplet state aryl cations recombination: A possible route to unusually stable doubly charged biphenyl cations

“…According to this concept, the nature of the activation barrier in bimolecular chemical reactions being determined by exchange repulsion between two closed shell molecules can also be interpreted in terms of their excited triplet state behavior, as shown in Figure . The height of the barrier and the heat of reaction are determined predominantly by the properties of the “double–triplet” singlet excited states of the reactants …”

“…The role of the double–triplet singlet state becomes more natural and more important in those reactions when it can be realized in a form of the ground state reactivity. This happens in the recombination of two triplet reactants: CH 2 ( 3 B 1 ) + CH 2 ( 3 B 1 ) = C 2 H 4 ( 1 A g ), an example representing the calculated reaction 2NO + O 2 ( 3 Σ g − ) = 2NO 2 . Here, the two NO radicals and molecular oxygen collide within the zero spin state, which finally dissociates to two NO 2 molecules.…”

Theoretical study on NOx adsorption properties over the α-MnO2(110) surface

“…35 Also, NO was found to be an intermediate in the industrial production of nitric acid. 36,37 Therefore, it is important to investigate the NO adsorption mechanism over the a-MnO 2 (110) surface to remove the vast majority of NO x as a raw material for the production of nitric acid. Before adsorption, the bond length of the free NO molecule was calculated to be 1.163 A, which is close to the experimental value (1.17Å).…”