Simulation of the nonbranched-chain addition of saturated free radicals to alkenes and their derivatives yielding 1: 1 adducts

Silaev, Michael M.

doi:10.1134/s0040579507030062

Cited by 8 publications

(41 citation statements)

References 5 publications

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“…[82]), is 3.9 times longer than that of the linear 3 HO  radical [68,83] estimated in the same way [66] for the same conditions [84], (9.1 ± 0.9) × 10 -6 s. MP2/6-311++G** calculations using the Gaussian-98 program confirmed that the cyclic structure of 4 HO  [85] is energetically more favorable than the helical structure [68] (the difference in energy is 4.8-7.3 kJ mol -1 , depending on the computational method and the basis set). 11 For example, with the MP2(full)/6-31G(d) method, the 11 There were calculations for the two conformers (cis and trans) of the The hydrogen molecule that results from reaction 5 in the gas bulk possesses an excess energy, and, to acquire stability within the approximation used in this work, it should have time for deactivation via collision with a particle M capable of accepting the excess energy [87]. To simplify the form of the kinetic equations, it was assumed that the rate of the bimolecular deactivation of the molecule substantially exceeds the rate of its monomolecular decomposition, which is the reverse of reaction [2].…”

Section: Methodsmentioning

confidence: 99%

“…The consecutive and parallel reactions involved in this free-radical nonbranched-chain addition process are presented below (Scheme 1). In the case of comparable component concentrations with a non-overwhelming excess of the saturated component, extra reaction (1b) (k 1b  0) is included in the initiation stage [10,11]. In the case of an overwhelming excess of the saturated component reaction (1b) is ignored (k 1b = 0) [8,9,12].…”

Section: Addition To the с=с Bond Of Alkenes And Their Derivativesmentioning

confidence: 99%

“…Eqs (10a) and (10a) were obtained by replacing the rate constant k 2 in Eqs. (10) and (11) with its analytical expression (for reducing the number of unknown parameters to be determined directly).…”

Section: The R (-H) H•••o(r)o 3 Ring Consisting Of the Same Six Atomsmentioning

confidence: 99%

“…This publication presents a comprehensive review of the nobranched-chain kinetic models developed for particular types of additions of saturated free radicals to multiple bonds [8][9][10][11][12][13][14]. It covers free radical additions to alkenes [10,11], their derivatives [8,9], formaldehyde (first compound in the aldehyde homological series) [8,9,12], and molecular oxygen [13,14] (which can add an unsaturated radical as well) yielding various 1:1 molecular adducts, whose formation rates as a function of the unsaturated compound concentration pass through a maximum (free radical chain additions to the С=N bond have not been studied adequately). In the kinetic description of these non-telomerization chain processes, the reaction between the 1:1 adduct radical and the unsaturated molecule, which is in competition with chain propagation through a reactive free radical ( • PCl 2 , С 2 Н 5 ĊНОН, etc.…”

mentioning

confidence: 99%

“…This reaction yields a low-reactive radical (such as СН 2 =С(СН 3 )ĊН 2 or НĊ=О) and thus leads to chain termination because this radical does not continue the chain and thereby inhibits the chain process [8]. We will consider kinetic variants for the case of comparable component concentrations with an excess of the saturated component [10,11] and the case of an overwhelming excess of the saturated component over the unsaturated component [8,9,12]. Based on the reaction schemes suggested for the kinetic description of the addition process, we have derived kinetic equations with one to three parameters to be determined directly.…”

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confidence: 99%

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New Kinetic Models of Free-Radical Nonbranched-Chain Addition to C=C, C=O, and O=O Molecular Bonds

Silaev¹

2019

International Journal of Advanced Research in Chemical Science

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A free radical may be low-reactive if its unpaired p-electron may be delocalized, e.g., over conjugated bonds as in the case of allyl radical CH 2 =CHĊH 2 or along a double bond from carbon to the more electron-affine oxygen as in the case of formyl radical HĊ=O. Note that the activity of a free radical is also connected to the reaction heat in which it participates. In nonbranched-chain processes of reactive free radical (addend) addition to double bonds of molecules, the formation of rather low-reactive free radicals in reactions, which are parallel to or competing with propagation via a reactive radicals, lead to chain termination, because these low-reactive radicals do not participate in further chain propagation and because they decay when colliding with each other or with chain-carrier reactive radicals thus resulting in inefficient expenditure of the latter and process inhibition. In similar processes involving the addend and inhibitor radicals in diffusion controlled bimolecular chain-termination reactions of three types, the dependences of the rate of molecular 1:1 adduct formation on the concentration of the unsaturated component (which is the source of low-reactive free radicals in a binary system of saturated and unsaturated components) have a maximum, usually in the region of small (optimal) concentrations. The progressive inhibition of nonbranched chain processes upon exceeding this optimal concentration may be an element of self-regulation of the natural processes returning them to a steady state condition. Here, reactions of addition of reactive free radicals to multiple bonds of alkenes, formaldehyde, and oxygen molecules to give 1:1 adduct radicals are taken as examples to consider the role of lowreactive free radicals as inhibitors of the nobranched chain processes at moderate temperatures. In the case of oxidation, there are tetraoxyl 1:2 adduct radical arising upon addition of a peroxyl 1:1 adduct

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Section: Methodsmentioning

confidence: 99%

Section: Addition To the с=с Bond Of Alkenes And Their Derivativesmentioning

confidence: 99%

Section: The R (-H) H•••o(r)o 3 Ring Consisting Of the Same Six Atomsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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New Kinetic Models of Free-Radical Nonbranched-Chain Addition to C=C, C=O, and O=O Molecular Bonds

Silaev¹

2019

International Journal of Advanced Research in Chemical Science

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Kinetics of the Free-Radical Nonbranched-Chain Addition

Silaev¹

2017

AJPST

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The aim of this study was the conclusion of simple kinetic equations to describe ab initio initiated nonbranched-chain processes of the saturated free-radical addition to the double bonds of unsaturated molecules in the binary reaction systems of saturated and unsaturated components. In the processes of this kind the formation rate of the molecular addition products (1:1 adducts) as a function of concentration of the unsaturated component has a maximum. Five reaction schemes are suggested for this addition processes. The proposed schemes include the reaction competing with chain propagation reactions through a reactive free radical. The chain evolution stage in these schemes involves three or four types of free radicals. One of them is relatively low-reactive and inhibits the chain process by shortening of the kinetic chain length. Based on the suggested schemes, nine rate equations (containing one to three parameters to be determined directly) are deduced using quasi-steady-state treatment. These equations provide good fits for the nonmonotonic (peaking) dependences of the formation rates of the molecular products (1:1 adducts) on the concentration of the unsaturated component in binary systems consisting of a saturated component (hydrocarbon, alcohol, etc.) and an unsaturated component (alkene, allyl alcohol, formaldehyde, or dioxygen). The unsaturated compound in these systems is both a reactant and an autoinhibitor generating low-reactive free radicals. A similar kinetic description is applicable to the nonbranched-chain process of the free-radical hydrogen oxidation, in which the oxygen with the increase of its concentration begins to act as an oxidation autoingibitor (or an antioxidant). The energetics of the key radical-molecule reactions is considered.

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Kinetic Equations of Free-Radical Nonbranched-Chain Processes of Addition

Silaev¹

2018

ECB

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The aim of this study was to devise simple kinetic equations to describe ab initio initiated nonbranched-chain processes of addition of saturated free-radical to double bonds of unsaturated molecules in binary reaction systems of saturated and unsaturated components. In these processes the formation rate of the molecular addition products (1:1 adducts) as a function of concentration of the unsaturated component reaches a limiting value. Five reaction schemes are suggested for the addition processes. The proposed schemes include the reaction competing with chain propagation reactions through a reactive free radical. The chain evolution stage in these schemes involves three or four types of free radicals. One of them is relatively low-reactive and inhibits the chain process by shortening of the kinetic chain length. Based on the suggested schemes, nine rate equations are deduced using quasi-steady-state treatment. These equations provide good fits for the non-monotonic (peaking) dependences of the formation rates of the molecular products (1:1 adducts) on the concentration of the unsaturated component in the binary systems. The unsaturated compound in these systems is both a reactant and an autoinhibitor generating low-reactive free radicals. A similar kinetic description is applicable to the nonbranched-chain process of the free-radical hydrogen oxidation, in which the oxygen with the increase of its concentration begins to act as an oxidation autoinhibitor (or an antioxidant). The energetics of the key radical-molecule reactions are considered.

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Simulation of the nonbranched-chain addition of saturated free radicals to alkenes and their derivatives yielding 1: 1 adducts

Cited by 8 publications

References 5 publications

New Kinetic Models of Free-Radical Nonbranched-Chain Addition to C=C, C=O, and O=O Molecular Bonds

New Kinetic Models of Free-Radical Nonbranched-Chain Addition to C=C, C=O, and O=O Molecular Bonds

Kinetics of the Free-Radical Nonbranched-Chain Addition

Kinetic Equations of Free-Radical Nonbranched-Chain Processes of Addition

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