A computational mechanistic study of the deamination reaction of melamine

Almatarneh, Mansour H.; Abu‐Saleh, Abd Al‐Aziz A.; Uddin, Kabir M.; Poirier, Raymond A.; Warburton, Peter L.

doi:10.1002/qua.25308

Cited by 12 publications

(5 citation statements)

References 66 publications

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“…This might be attributed to the number of hydrogen bonds formed in the reaction. This is consistent with our previous work where the barriers drop significantly for the water-mediated reactions. − Furthermore, the presence of a second H 2 O molecule increases the electronegativity with the contribution of the lone pair of electrons with the hydrogen atom mediation.…”

Section: Resultssupporting

confidence: 93%

Hydration and Secondary Ozonide of the Criegee Intermediate of Sabinene

et al. 2018

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A computational study of the formation of secondary ozonide (SOZ) from the Criegee intermediates (CIs) of sabinene, including hydration reactions with H 2 O and 2H 2 O, was performed. All of the geometries were optimized at the B3LYP and M06-2X with several basis sets. Further single-point energy calculation at the CCSD(T) was performed. Two major pathways of SOZ formation suggest that it is mainly formed from the sabinene CI and formaldehyde rather than sabina ketone and formaldehyde-oxide. However, in both pathways, the activation energies are within a range of ±5 kJ mol –1 . Furthermore, the hydration reactions of the anti-CI with H 2 O and 2H 2 O showed that the role of the second water molecule is a mediator (catalyst) in this reaction. The dimer hydration reaction has lower activation energies than the monomer by 60 and 69 kJ mol –1 , at the M06-2X/6-31G(d) and CCSD(T)+CF levels of the theory, respectively. A novel water-mediated vinyl hydroperoxide (VHP) channel from both the monomer and dimer has been investigated. The results indicate that the direct nonmediated VHP formation and dissociation is interestingly more possible than the water-mediated VHP. The density functional theory calculations show that the monomer is faster than the dimer by roughly 22 kJ mol –1 . Further, the infrared spectrum of sabina ketone was calculated at B3LYP/6-311+G(2d,p); the calculated carbonyl stretching of 1727 cm –1 is in agreement with the experimental range of 1700–1800 cm –1 .

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Section: Resultssupporting

confidence: 93%

Hydration and Secondary Ozonide of the Criegee Intermediate of Sabinene

et al. 2018

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“…The previous works of the 1,3-proton shift has shown that the barrier could drop significantly when the water molecule is involved, acting as a mediator [53][54][55][56][57][58][59][60][61][62][63][64][65]. Figure 5 shows the one-step nucleophilic addition mechanism for the monohydrated reaction between the methanol and CI.…”

Section: Potential Energy Surface For the Reaction Of Methanol With Cmentioning

confidence: 99%

A Computational Study of the Ozonolysis of Phenanthrene

et al. 2017

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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.

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“…Hence, the mechanistic discussion is mainly about the more plausible reaction of anti-CI with (H 2 O) 2 , pathway F. The second water molecule acts as a mediator, thus, increasing the number of hydrogen bonds and decreasing the energy barrier. [63][64][65][66][67][68][69][70][71][72] The reaction mechanisms of pathways E and F are given in Figures 9 and S12 to S14, respectively.…”

Section: Unimolecular Dissociation Of the Ci's Through The Ester Chmentioning

confidence: 99%

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

Almatarneh

Elayan

Abu‐Saleh

et al. 2018

Int J of Quantum Chemistry

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The gas‐phase ozonolysis reaction of methylbutenol through the Criegee mechanism is investigated. The initial reaction leads to a primary ozonide (POZ) formation with barriers in the range of 10–28 kJ mol−1. The formation of 2‐hydroxy‐2‐methyl‐propanal (HMP) and formaldehyde‐oxide is more favorable, by 10 kJ mol−1, than the syn‐CI and formaldehyde. The unimolecular dissociation of the more stable syn‐CI via 1,5‐H transfer into an epoxide is more favored than the epoxide and 3O2 formation. The ester channel led to the formation of the acetone and formic acid favorably from the anti‐CI. The hydration of the anti‐CI with H2O and (H2O)2 is significantly barrierless with a higher plausibility to the latter, and thus they may lead to the formation of peroxides and ultimately OH radicals, as well as airborne particulate matter. Reaction of anti‐CI with water dimers enhances its atmospheric reactivity by a factor of 28 in reference to water monomers.

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A computational mechanistic study of the deamination reaction of melamine

Cited by 12 publications

References 66 publications

Hydration and Secondary Ozonide of the Criegee Intermediate of Sabinene

Hydration and Secondary Ozonide of the Criegee Intermediate of Sabinene

A Computational Study of the Ozonolysis of Phenanthrene

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

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