Protolytic Reactions of 3,6-DI-tert-Butyl-2-Hydroxyphenoxyl with Nitrogen Bases

Masalimov, A. S.; Tur, A.A.; Nikolskiy, S.N.

doi:10.1007/s11237-016-9451-0

Cited by 3 publications

(3 citation statements)

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“…The Arrhenius plot showed a good linear relationship between lgkexch and 1/T (Fig. 2 Table 1 shows similar parameters of hexanoic, hexanedioic, 2-anilinobenzoic acids and dodecan-1amine for comparison [17,18]. Analysis of available data suggests that despite their amphoteric nature 2and 6-aminohexanoic acids in toluene react with the spin probe at a rate comparable to the rate of the proton exchange reaction with aliphatic monocarboxylic acids (hexanoic acid is given for an example).…”

Section: Resultsmentioning

confidence: 90%

“…Analysis of available data suggests that despite their amphoteric nature 2and 6-aminohexanoic acids in toluene react with the spin probe at a rate comparable to the rate of the proton exchange reaction with aliphatic monocarboxylic acids (hexanoic acid is given for an example). The value of this rate is far from the rates with aliphatic amines [18]. Therefore, a proton of the carboxyl group of aminohexanoic acid is involved in the proton exchange.…”

Section: Resultsmentioning

confidence: 90%

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ESR-Study of the Proton Exchange with Aliphatic Amino Acids in Toluene

Stadnik

Abilkanova

Kudryavtseva

et al. 2022

Bull. of the Kar. Univ. "Chem". Ser.

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This paper presents the results of an ESR spectroscopic study of the intermolecular proton exchange kinetics with some isomers of aminocaproic acid, such as 2-aminohexanoic and 6-aminohexanoic acids in the toluene indifferent medium. A stable semiquinone radical, namely 3,6-di-tert-butyl-2-hydroxyphenoxyl, was used as a spin probe. The ESR spectra were recorded on a RE-1306 spectrometer. The obtained dynamic spectra of the intermolecular proton exchange process are given in this article. Modeling of the proton exchange ESR spectra was carried out using a previously developed program, which is based on a four-jump model of this reaction and modified Bloch equations. The kinetic parameters of the process of acid-base interaction of the spin probe with amino acids and the activation barrier of the reaction were estimated with a minimum error based on a comparison of the model spectra with the experimental ones. The obtained data were analyzed and compared with previously known information. It was found that the reaction rate of the intermolecular proton exchange between 3,6-di-tert-butyl-2-hydroxyphenoxy and studied aliphatic amino acids is comparable to the same with aliphatic carboxylic acids. But in our case, there is an increase in the activation barrier, which apparently is associated with a negative effect on the intramolecular hydrogen bonding process between the amino and the carboxyl groups in the amino acid molecule

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Section: Resultsmentioning

confidence: 90%

Section: Resultsmentioning

confidence: 90%

ESR-Study of the Proton Exchange with Aliphatic Amino Acids in Toluene

Stadnik

Abilkanova

Kudryavtseva

et al. 2022

Bull. of the Kar. Univ. "Chem". Ser.

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“…The stable semiquinone radical 3,6-di-tert.butyl-2-oxyphenoxyl (I) was used as acid spin probe for investigations of protolytic ability of different acids and bases such as carbonic acids, alcohols, tertiary amines, alkaloids, nitrogen heterocycles in organic solutions [5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Investigation of intermolecular proton exchange of 3,6-di-tert-butyl-2-oxyphenoxyl withN-phenylanthranilic acid by ESR spectroscopy method

Nikolskiy¹,

Abilkanova²,

Golovenko³

et al. 2020

Bull. of the Kar. Univ. "Chem". Ser.

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Investigation of intermolecular proton exchange of 3,6-di-tert-butyl-2-oxyphenoxyl with N-phenylanthranilic acid by ESR spectroscopy method In this work we studied the intermolecular proton exchange (IPE) reaction between the spin probe of 3,6-ditert-butyl-2-hydroxyphenoxyl (I) and the aromatic amino acid N-phenylanthranilic acid (N-PhAA). The experimental spectra of the 3,6-di-tert-butyl-2-hydroxyphenoxyl-N-phenylanthranilic acid system were recorded using dynamic EPR spectroscopy. The studies were carried out in a non-aqueous indifferent solvent toluene in a wide temperature range. The theoretical EPR spectra of the radical IN -PhAA system corresponding to various process rates were successfully simulated using the ESR-EXHANGE program. This program is written in the modern version of the algorithmic language Fortran 90. The general line-form equation for the four-jump model have been derived from the modified Bloch equations. The second-order rate constants for the intermolecular proton exchange process between radical I and N-PhAA were determined by comparison of the experimental and simulated EPR spectra. The iterative least squares procedure was used for computer analysis of the kinetic data of intermolecular proton exchange and for obtaining activation parameters of the reaction. From kinetic data it follows that N-phenylanthranilic acid has the lowest value of protolytic ability in comparison with aminobenzoic acids.

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Proton exchange between oxymethyl radical and acids and bases: semiempirical quantum-chemical study

Pustolaikina¹,

Kutzhanova²,

Stadnik³

et al. 2016

KazNU Chem Bull

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The reactions with proton participation are widely represented in the analytical, technological and biological chemistry. Quantum-chemical study of the exchange processes in hydrogen bonding complexes will allow us to achieve progress in the understanding of the elementary act mechanism of proton transfer in hydrogen bonding chain as well as the essence of the acid-base interactions. Oxymethyl radical •CH2ОН is small in size and comfortable as a model particle that well transmits protolytic properties of paramagnetic acids having more complex structure. Quantum-chemical modeling of proton exchange reaction oxymethyl radical ∙CH2OH and its diamagnetic analog CH3OH with amines, carboxylic acids and water was carried out using UAM1 method with the help of Gaussian-2009 program. QST2 method was used for the search of transition state, IRC procedure was applied for the calculation of descents along the reaction coordinate. The difference in the structure of transition states of ∙CH2OH/ CH3OH with bases and acids has been shown. It has been confirmed that in the case of bases, consecutive proton exchange mechanism was fixed, and in the case of complexes with carboxylic acids parallel proton exchange mechanism was fixed. The similarity in the reaction behavior of paramagnetic and diamagnetic systems in the proton exchange has been found. It was suggested that the mechanism of proton exchange reaction is determined by the structure of the hydrogen bonding cyclic complex, which is, in turn, depends from the nature of the acid-base interactions partners.

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Protolytic Reactions of 3,6-DI-tert-Butyl-2-Hydroxyphenoxyl with Nitrogen Bases

Cited by 3 publications

References 1 publication

ESR-Study of the Proton Exchange with Aliphatic Amino Acids in Toluene

ESR-Study of the Proton Exchange with Aliphatic Amino Acids in Toluene

Investigation of intermolecular proton exchange of 3,6-di-tert-butyl-2-oxyphenoxyl withN-phenylanthranilic acid by ESR spectroscopy method

Proton exchange between oxymethyl radical and acids and bases: semiempirical quantum-chemical study

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