The Decomposition of Amines in the Vapor Stage

Upson, Fred W.; Sands, Lila

doi:10.1021/ja01431a029

Cited by 5 publications

(4 citation statements)

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“…The decomposition of cis -PA, as other separate pathways occur, is due to the geometry of the PA; in which the trans -PA cannot undergo these reaction mechanisms and vice versa. Furthermore, the decomposition from both stereoisomers to form H 2 proves that the yield of 6.3% cannot be neglected and might be more than expected . For example, TSG through pathway G is a different one that leads to the formation of prop-1-en-1-amine and H 2 (similar to pathway E but with geometric isomerism).…”

Section: Resultsmentioning

confidence: 97%

“…Furthermore, the decomposition from both stereoisomers to form H 2 proves that the yield of 6.3% cannot be neglected and might be more than expected. 33 For example, TSG through pathway G is a different one that leads to the formation of prop-1-en-1-amine and H 2 (similar to pathway E but with geometric isomerism). However, bond lengths and activation energies of TSG differ from TSE ; this is attributed to the terminal alkene that is being formed in TSE which is less sterically hindered than TSG .…”

Section: Resultsmentioning

confidence: 99%

“…28 PA has a peculiar property in that it dissociatively ionize with the production of alkyl-free radicals in addition to methylenimmonium ion CH 2 NH 2 + 29 which is considerably stabilized by the formation of C=N π-bond, 30 whereas the NH 3 loss, that is analogous to the dehydration of n -propylalcohol, is unfavorable 31 due to the electrostatic repulsion between the terminal heavy atoms. 32 In the presence of kaolin, 33 the PA is decomposed into hydrogen cyanide (6.6%), propylene (6.4%), H 2 (6.3%), N 2 (4.6%), and ethylene (3.0%). On the silicon Si surface, eight decomposition products were studied theoretically.…”

Section: Introductionmentioning

confidence: 99%

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Unimolecular Decomposition Reactions of Propylamine and Protonated Propylamine

et al. 2019

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A detailed computational study of the decomposition reaction mechanisms of cis -propylamine ( cis -PA), trans -propylamine ( trans -PA), and the cis-isomer of its protonated form ( cis -HPA) has been carried out. Fourteen major pathways with their kinetic and thermodynamic parameters are reported. All reported reactions have been located with a concerted transition state, leading to significant products that agree with previous theoretical and experimental studies. Among six decomposition pathways of trans -PA, the formation of propene and NH 3 is the significant one, kinetically and thermodynamically, with an activation energy barrier of 281 kJ mol –1 . The production of two carbenes is found via two different transition states, where the reactions are thermodynamically controlled and reversible. Furthermore, five decomposition pathways of cis -PA have been considered where the formation of ethene, methylimine, and H 2 is the most plausible one with an activation energy barrier of 334 kJ mol –1 . The results show that the formation of propene and NH 4 + from the decomposition of cis -HPA is the most favorable reaction with an activation barrier of 184 kJ mol –1 , that is, the lowest activation energy calculated for all decomposition pathways.

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Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Unimolecular Decomposition Reactions of Propylamine and Protonated Propylamine

et al. 2019

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“…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 .…”

Section: Introductionmentioning

confidence: 99%

Computational study of the unimolecular and bimolecular decomposition mechanisms of propylamine

Almatarneh

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...

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