Kinetics and Mechanism of the Second Order Cyclization of the Cation Radicals Derived from 1,2-Diarylethanes.

Aalstad, Bjørg; Ronlán, Alvin; Parker, Vernon D.; Johansson, Lars; Persson, Malin; Thorberg, Seth-Olof; Ulff, Bengt

doi:10.3891/acta.chem.scand.36b-0171

Cited by 6 publications

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“…7); the energy of this delocalized orbital (3e HOMO , see table) is 0.53 eV higher than the energy of the n electrons of the S atoms of the disulfide bridge; therefore, the redox properties in oxidation of IX are determined by the MeOC 6 H 4 OCH 2 fragment. The fact that the oxidation potential E p of IX is 250 mV lower than E p of V3VIII and is within the range characteristic of dialkoxybenzenes (E p~1 .053 1.12 V [28,30]) also supports this conclusion. The HOMO of X is again localized on the S atom, but on that of the sulfide, and not disulfide, fragment (Fig.…”

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Electrochemical Oxidation of Disulfides Derived from Isocyanuric Acid

Grogger

Фаттахов

Jouikov³

et al. 2005

Russ J Gen Chem

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Anodic oxidation of linear and bicyclic disulfides derived from isocyanuric acid was studied by cyclic voltammetry and numerical simulation. The PM3 molecular modeling revealed three types of the highest occupied molecular orbitals determining the electrochemical reactivity of these compounds: n electrons of the sulfur atoms of the disulfide bridge in linear and N3Me-and N3Ph-substituted bicyclic disulfides, p electrons of the aromatic fragment in the disulfide with the N-2-(2-methoxyphenoxy)ethyl isocyanurate substituent, and n electrons of the sulfide sulfur atoms in the compound with the 3SS3 and 3S3 fragments in the aliphatic chain. Oxidation of the disulfides with the SS-localized highest occupied molecular orbital follows the scheme with reversible electron transfer, followed by a fast potential-determining second-order reaction and a slow current-determining first-order reaction (ECC mechanism). The isocyanurate heterocycle does not participate directly in redox transformations but stabilizes the electrochemically generated radical cations by the mechanism of transannular interaction.Linear and cyclic disulfides are being actively studied in view of their important role in the metabolism of living bodies (sulfur-containing enzymes [1], intra-and intercellular ion transfer [235], stabilization of proteins [2, 4], etc.), and also because of their specific properties used in redox-reversible systems [6,7], for selective complexation, determination, and extraction, and in fields based on molecular recognition [6,8,9]. New prospects are opened by a combination of a disulfide bridge with O-and N-containing fragments and with groups bearing known or potential bioactive centers. The electrochemical methods is one of the most convenient tools for studying redox transformations of these compounds. Despite the fact that organic disulfides were among the first objects in organic electrochemistry, the majority of studies on their electrochemistry concerned the behavior of the thiol3disulfide couple; the anodic processes involving disulfides are less studied [10 312]. Depending on the experimental conditions, oxidation of diorganyl disulfides can yield oxygen-containing compounds [13] or S-centered electrophilic intermediates reacting with unsaturated compounds [14]. Oxidation of diaryl [153 17] and dialkyl [18321] disulfides in aprotic and weakly nucleophilic media is also well studied. Much less data are available on oxidation of biologically active disulfides [22]. To reveal the character of the electron transfer and elucidate the primary steps of electrochemical transformations in oxidation of biologically active disulfides containing isocyanurate fragment, we considered in this work the oxidation of I3X. 7 N

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“…4). This mechanism corresponds to the oxidation schemes suggested for di- [28] and trialkoxybenzenes [29].…”

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confidence: 89%