Kinetics of low-temperature initiated oxidation of ethylbenzene inhibited by polyhydroxynaphthoquinones

Boguslavskaya, L. V.; Maksimov, O. B.; Khrapova, N. G.; Кулеш, Н. И.

doi:10.1007/bf00957411

Cited by 4 publications

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“…The energetically most favorable isomeric forms of radicals 2 and 3 and anions 6 and 7 are the tautomer C and type II rotamers 2C (3) , 3C (2) , 6C (3) , and 7C (2) , * Figure in parentheses at an oxygen atom denotes the number of the carbon atom to which the oxygen atom is bonded. Table 2.…”

Section: Methodsmentioning

confidence: 99%

“…All isomers of compounds 1-11 listed in Table 2 rather than only the energetically most favorable isomers con tribute to the energy balances of reactions (1) and (2). The contribution of the conformational mobility of the compounds under study to the energy balance of reac tions can be included using the effective Gibbs energies…”

Section: Methodsmentioning

confidence: 99%

“…Now we will illustrate the notations of isomers taking compound 7 as an example. In particular, the notation "7C (2),(4) " (mixed type (type IV) rotamer, see Scheme 2) denotes the type C tautomer (type I rotamer, see Scheme 2) of compound 7, the subscript "(2)" denotes the rotamer with respect to rotation of the β OH group at the C(2) atom (type II rotamer with respect to 7C), and the subscript "(4)" denotes the rotamer with respect to rota tion of the α OH group at the C(4) atom (type III rotamer with respect to 7C (2) ).…”

Section: Methodsmentioning

confidence: 99%

“…2) by the (U)B3LYP/6 311G(d) method (Table 2). Only these isomers of compounds 1-11 were taken into account in considering the spin density distribu tions in the molecules and the energy balances of reac tions (1) and (2).…”

Section: Methodsmentioning

confidence: 99%

“…Nevertheless, experiments showed that compound 1 is an efficient antioxidant. [1][2][3][4] The ishemized myocard is characterized by enhanced lipid peroxidation and reduced activity of antioxidant protective enzymes. The data accumulated to date suggest an oxygen free radical mechanism of autoaggression in the case of ishemic heart disease and acute myocardial infarction and involvement of the active forms of oxygen (AFO) in cardiovascular pathology.…”

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7-Ethyl-2,3,5,6,8-pentahydroxy-1,4-naphthoquinone (echinochrome A): A DFT study of the antioxidant mechanism. 1. Interaction of echinochrome A with hydroperoxyl radical

2007

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The molecular geometry and electronic structure of hydroxy substituted naphthazarin (NZ) 7 ethyl 2,3,5,6,8 pentahydroxy 1,4 naphthoquinone (echinochrome A, (Et)NZ(β OH) 3 , 1) were calculated by the B3LYP/6 311G(d) method. The influence of the (i) character of the β OH groups dissociation and (ii) conformational mobility of molecule 1 and the anions, radicals, and radical anions derived from 1 on the energy of their reactions with hydroperoxyl radical was studied by the (U)B3LYP/6 31G and (U)B3LYP/6 311G(d) methods. The enol enolic tautomerism due to the transfer of hydrogen atoms of α OH groups and rotational isomerism of the β OH groups at the C(2) and C(3) atoms and of the α OH groups at the C(5) and C(8) atoms were studied. The equilibrium in the gas phase reaction 1 + • OOH (Et)(HO β) 2 NZ(β О • ) + НOOH (1) (quenching of hydroperoxyl radical) is shifted to the separated reagents. Heterolysis of the O-H bond in one of the three β hydroxy groups considerably reduces the energy of subsequent O-H bond homolysis in either of the two remaining β hydroxy groups. As a consequence, the reaction (Et)(HO β) 2 NZ(β O -) + • OOH (Et)(HO β, -О β)NZ(β О • ) + НOOH (2) (quenching of hydroperoxyl radical) becomes exothermic and the equilibrium is shifted to the formation of hydrogen peroxide. The Gibbs energy gain in reaction (2) varies from -6.4 to -10.9 kcal mol -1 depending on which β hydroxy group is involved in the O-H bond homolysis.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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