Kinetic barriers, rate constants and branching ratios for unimolecular reactions of methyl octanoate peroxy radicals: A computational study of a mid-sized biodiesel fuel surrogate

2017 ◽  
Vol 180 ◽  
pp. 148-157 ◽  
Author(s):  
Hairong Tao ◽  
Kuang C. Lin
Keyword(s):  
Rate Constants ◽  
Computational Study ◽  
Branching Ratios ◽  
Biodiesel Fuel ◽  
Peroxy Radicals ◽  
Unimolecular Reactions ◽  
Methyl Octanoate ◽  
Fuel Surrogate ◽  
Kinetic Barriers

Computational Study on the Kinetics and Mechanisms of Unimolecular Reactions of (Z)-(Z)-N-(λ5-phosphanylidene) Formohydrazonic Formic Anhydride: Intramolecular aza-Wittig Reaction in Competition with Mumm Rearrangement

2020 ◽  
Vol 17 (11) ◽  
pp. 884-889
Author(s):  
Somayeh Mirdoraghi ◽  
Hamed Douroudgari ◽  
Farideh Piri ◽  
Morteza Vahedpour
Keyword(s):  
Rate Constants ◽  
Density Functional ◽  
Wittig Reaction ◽  
Computational Study ◽  
Single Step ◽  
Low Energy ◽  
Coupled Cluster ◽  
Unimolecular Reaction ◽  
Single Step Reaction ◽  
Good Agreement

For (Z)-(Z)-N-(λ5-phosphanylidene) formohydrazonic formic anhydride, Aza-Wittig reaction and Mumm rearrangement are studied using both density functional and coupled cluster theories. For this purpose, two different products starting from one substrate are considered that are competing with each other. The obtained products, P1 and P2, are thermodynamically favorable. The product of the aza-Wittig reaction, P1, is more stable than the product of Mumm rearrangement (P2). For the mentioned products, just one reliable pathway is separately proposed based on unimolecular reaction. Therefore, the rate constants based on RRKM theory in 300-600 K temperature range are calculated. Results show that the P1 generation pathway is a suitable path due to low energy barriers than the path P2. The first path has three steps with three transition states, TS1, TS2, and TS3. The P2 production path is a single-step reaction. In CCSD level, the computed barrier energies are 14.55, 2.196, and 10.67 kcal/mol for Aza-Wittig reaction and 42.41 kcal/mol for Mumm rearrangement in comparison with the corresponding complexes or reactants. For final products, the results of the computational study are in a good agreement with experimental predictions.

Absolute rate constants for hydrocarbon autoxidation. VI. Alkyl aromatic and olefinic hydrocarbons

1967 ◽  
Vol 45 (8) ◽  
pp. 793-802 ◽  
Author(s):  
J. A. Howard ◽  
K. U. Ingold
Keyword(s):  
Hydrogen Atom ◽  
Steric Hindrance ◽  
Rate Constants ◽  
Peroxy Radical ◽  
Electron System ◽  
Chain Termination ◽  
The Self ◽  
Hydrogen Atom Abstraction ◽  
Peroxy Radicals ◽  
Absolute Rate

Absolute rate constants have been measured for the autoxidation of a large number of hydrocarbons at 30 °C. The chain-propagating and chain-terminating rate constants depend on the structure of the hydrocarbon and also on the structure of the chain-carrying peroxy radical. With certain notable exceptions which are mainly due to steric hindrance, the rate constants for hydrogen-atom abstraction increase in the order primary < secondary < tertiary; and, for compounds losing a secondary hydrogen atom, the rate constants increase in the order unactivated < acyclic activated by a single π-electron system < cyclic activated by a single Π-system < acyclic activated by two π-systems < cyclic activated by two π-systems. The rate constants for chain termination by the self-reaction of two peroxy radicals generally increase in the order tertiary peroxy radicals < acyclic allylic secondary  [Formula: see text] cyclic secondary  [Formula: see text] acyclic benzylic secondary < primary peroxy radicals < hydroperoxy radicals.

scholarly journals Unimolecular Reactions of Peroxy Radicals Formed in the Oxidation of α-Pinene and β-Pinene by Hydroxyl Radicals

2019 ◽  
Vol 123 (8) ◽  
pp. 1661-1674 ◽  
Author(s):  
Lu Xu ◽  
Kristian H. Møller ◽  
John D. Crounse ◽  
Rasmus V. Otkjær ◽  
Henrik G. Kjaergaard ◽  
...  
Keyword(s):  
Hydroxyl Radicals ◽  
Peroxy Radicals ◽  
Unimolecular Reactions

Studies of radiation-induced reactions of ethylene in aqueous solution II. Reactions in the presence of oxygen as studied by pulse radiolysis and γ -irradiation techniques

1967 ◽  
Vol 300 (1463) ◽  
pp. 443-454 ◽  
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Peroxide ◽  
Rate Constants ◽  
Pulse Radiolysis ◽  
Major Product ◽  
Peroxy Radicals ◽  
Ferrous Ions ◽  
Constant Composition ◽  
Γ Irradiation ◽  
Radiation Induced

The radiolysis of dilute aqueous solutions containing ethylene and oxygen has been investigated. Pulse radiolysis was used to measure the rate constants for the addition of hydroxyl radicals to ethylene, the binary decomposition of the resulting hydroxyethyl radicals and their addition to ethylene and reaction with oxygen to yield peroxy radicals. The rate constants have also been determined for the mutual interaction of the peroxy radicals and their reaction with ferrous ions. The principal products of γ -irradiation were aldehydes and organic hydroperoxides. Hydrogen peroxide was found in yields close to the molecular yield from water. The polymer produced in the absence of oxygen was not formed, and glycollaldehyde, reported as a major product by previous workers, could not be detected. At constant composition of the gas mixtures, product yields were unaffected by total pressure in the range up to 40 atm, but were strongly dependent on the proportion of oxygen. Aldehyde yields were markedly greater at pH 1.2 than in neutral solution. The influence of ferrous ions an d of added hydrogen peroxide has been determined. The pulse radiolysis and γ -irradiation experiments complement one another and show that the radiation-induced oxidation of ethylene in aqueous solution involves the same primary reactions as occur in the absence of oxygen, followed by the formation and further reactions of peroxy radicals.

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