Computational study for the second-stage cracking of the pyrolysis of ethylamine: Decomposition of methanimine, ethenamine, and ethanimine

Int J of Quantum Chemistry

Elayan

Abu‐Saleh

et al. 2018

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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.

Section: Resultsmentioning

confidence: 99%

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

Int J of Quantum Chemistry

Elayan

Abu‐Saleh

et al. 2018

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“…Thereafter, single-point energy calculations were performed using CBS-QB3 22 . These levels of theory based on our previous studies of the decomposition pathways of different amines [23][24][25][26] . Relative energies of all stationary points were revised with zero-point vibrational energies (ZPE).…”

Section: Methodsmentioning

confidence: 99%

Computational study of the unimolecular and bimolecular decomposition mechanisms of propylamine

Omari

Omeir

et al. 2020

Sci Rep

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A detailed computational study of the dehydrogenation reaction of trans-propylamine (trans-pA) in the gas phase has been performed using density functional method (DFT) and CBS-QB3 calculations. Different mechanistic pathways were studied for the reaction of n-propylamine. Both thermodynamic functions and activation parameters were calculated for all investigated pathways. Most of the dehydrogenation reaction mechanisms occur in a concerted step transition state as an exothermic process. the mechanisms for pathways A and B comprise two key-steps: H 2 eliminated from pA leading to the formation of allylamine that undergoes an unimolecular dissociation in the second step of the mechanism. Among these pathways, the formation of ethyl cyanide and H 2 is the most significant one (pathway B), both kinetically and thermodynamically, with an energy barrier of 416 kJ mol −1. the individual mechanisms for the pathways from c to n involve the dehydrogenation reaction of PA via hydrogen ion, ammonia ion and methyl cation. The formation of α-propylamine cation and nH 3 (pathway E) is the most favorable reaction with an activation barrier of 1 kJ mol −1. this pathway has the lowest activation energy calculated of all proposed pathways. Propylamine is of significant importance in chemistry, as it constitutes a central structure block for aliphatic amines 1. It is widely utilized as a solvent in organic synthesis, and as a finishing agent for drugs, rubber, fiber, paints, pesticides, textile and resin 2,3 , and in the generation of fungicides 4-6. Furthermore, it may very well be used as a petroleum additive and preservative. The disintegration of protonated of propylamine has attracted a noteworthy arrangement of fascination in the previous decade 7-10. This is mainly due to the way that the proton affinity and the structural difference in propylamine through protonation influences the separation items through the arrangement of protonated amines, methane, propene and hydrogen gas 11,12. Additionally, this reaction prompts the generation of various poisonous synthetic substances such as, alkyl cyanide, propylene, ethylene, nitrogen and hydrogen gases 13,14. Protonation (B + H + → BH +) and deprotonation (dehydrogenation) (HA − H + → A −) reactions assume a significant role in natural science and organic chemistry, where A and B are the acidic and the basic centers, respectively. They are considered as the first step in several fundamental chemical mechanisms elucidated in the cited reference 15. The ability of an atom or molecule in the gas phase to accept or to lose a proton can be described by calculating the proton affinity (PA), deprotonation (dehydrogenation) enthalpy, and molecular gasphase basicity, which offer a profound understanding of the connections between the reactivity of the organic molecules, their molecular structures, and molecular stability 16. The negative of the enthalpy change related to the gas-phase protonation reaction is referred to as proton affinity, while dehydrogenation energy is defined as the en...

“…Brown grease can also undergo pyrolysis to a kerosene-like mixture of hydrocarbons under relatively mild conditions [15][16][17]. e pyrolysis reaction, our concern, is defined as a high-temperature reaction in the absence of oxygen [18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Mechanistic Investigation of the Pyrolysis of Brown Grease

Alnemrat

Omeir

et al. 2020

Journal of Chemistry

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The conversion of brown grease using pyrolysis reactions represents a very promising option for the production of renewable fuels and chemicals. Brown grease forms a mixture of alkanes, alkenes, and ketones at a temperature above 300°C at atmospheric pressure. This work is a computational study of the detailed reaction mechanisms of brown grease pyrolysis using DFT methodology. Prior experimental investigations confirmed product formation consistent with a set of radical reactions with CO2 elimination, as well as ketone by product formation, CO forming reactions, and formation of alcohols and aldehydes as minor byproducts. In this work, computational quantum chemistry was used to explore these reactions in greater detail. Particularly, a nonradical pathway formed ketone byproducts via the ketene, which we refer to as Pathways A1 and A2. Radical formation by thermal decomposition of unsaturated fatty acids initiates a set of reactions which eliminate CO2, regenerating alkyl radicals leading to hydrocarbon products (Pathway B). A third pathway (Pathway C) is an alternative set of radical reactions, resulting in decarbonylation and formation of minor byproducts. The results of the calculations are in good agreement with recent experimental studies.