A Computational Study of the Ozonolysis of Phenanthrene

Abstract

A computational study of the ozonolysis of phenanthrene has been carried out using DFT methods (B3LYP and M06-2X). The reaction mechanism for the ozonolysis was studied in both gas phase and in solution, using the polarizable continuum solvation model. The structures for all proposed reaction mechanisms were optimized using M06-2X and B3LYP methods with 6-31G(d), 6-31+G(d), and 6-31G(2df,p) basis sets. In solution, all structures were optimized using B3LYP/6-31+G(d,p) and polarizable continuum solvation model. Six different mechanistic pathways were explored for the ozonolysis of phenanthrene that forms aldehyde compounds. The activation energy of the formation of the primary ozonide intermediate in pathway A is 13 kJ mol −1 in the polarizable continuum model with the B3LYP/6-31+G(d,p) method. This reaction is followed by a dissociation into a zwitterionic Criegee intermediate with an activation energy of 76 kJ mol −1 in polarizable continuum model with B3LYP/6-31+G(d,p). Furthermore, the nucleophilic addition reactions of methanol to the Criegee intermediate have been studied along two pathways, B1 and B2. The water-mediated mechanism for pathways B2 and C2, where the water molecule acts as a mediator through a 1,5-proton shift, dropped the activation barriers by 18 and 26 kJ mol −1 , respectively, based on B3LYP/6-31G(2df,p) method. The solvation model (polarizable continuum) reduces the energy barriers for all pathways except for the reaction of methanol with the Criegee intermediate. This study provides an insight into understanding the mechanism of transformation of this pollutant into non-toxic compounds.

Computational Study of the Dissociation Reactions of Secondary Ozonide

“…The theoretical work by Jørgensen and Gross afforded an insight into the experimental work of Naa and co-workers by surveying plausible, pertinent reaction mechanisms [18]. Moreover, our previous work on ozonolysis reactions provided good initial guesses that helped us attain a complete picture about the proposed mechanisms for this study [7,[19][20][21][22][23].…”

“…SOZ is formed when a stabilized Criegee intermediate undergoes a 1,3-dipolar cycloaddition to the carbonyl compound, as shown in Figure 1. SOZ is more stable than primary ozonide and exhibits a sufficiently long lifetime [5][6][7]. The formation of SOZ from alkenes has been reported in numerous studies [8,9] with a prime focus on the formation and relative stability of SOZs resulting from the ozonolysis of selected cyclic monoterpenes (C 10 H 16 ) [10] taking place in both a gas and a liquid phase.…”

Renewable production of high density jet fuel precursor sesquiterpenes from Escherichia coli

“…The thermodynamic parameters of the two compounds were calculated by means of density functional theory (DFT) method using Gaussian 09 software. All the DFT calculations were performed using the hybrid B3LYP method with the 6-311+G(2d,p) basis set level [ 26 , 41 ], which can provide a nice balance between cost and accuracy, and is known to perform very well for the prediction of geometries of compounds. The specific energy was calculated following the steps of the isodesmic reaction to get the standard enthalpy of formation, as well as considering the combustion reaction equation to get the enthalpy values of combustion.…”

The gas‐phase ozonolysis reaction of methylbutenol: A mechanistic study

“…The quantum calculations using density functional theory (DFT) and composite methods were performed utilizing the Gaussian 09 package . The rate constant of the ozonolysis reaction and it is resulting reactions has been computed using transition state theory (TST) at 298.15 K. The selection of methods and basis sets is based on our previous work on the atmospheric ozonolysis reaction mechanisms of sabinene and phenanthrene . The stationary and saddle points were optimized using the B3LYP method with the split‐valence polarized 6‐31G(d,p) basis set.…”