Pulse radiolysis of aqueous solutions of thiosulphate

Mehnert, R.; Brede, O.; Janovský, I.

doi:10.1016/0146-5724(84)90138-9

Cited by 21 publications

(28 citation statements)

References 5 publications

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“…This suggests that the polarity of the medium is not the only property of the solvent responsible for the change in rate with change in the solvent composition. The values of relative permittivity of acetic acid-water mixtures have been estimated from the corresponding values of the pure solvents 16 . The effect of solvent composition was analysed using the Grunwald-Winstein 17 equation, log k 2 = mY + log k 0 .…”

Section: Discussionmentioning

confidence: 99%

Kinetics and mechanism of the oxidation of some diols by benzyltrimethylammoniumtribromide

2001

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The kinetics of oxidation of five vicinal and four non-vicinal diols, and two of their monoethers by benzyltrimethylammonium tribromide (BTMAB) have been studied in 3:7 (v/v) acetic acid-water mixture. The vicinal diols yield the carbonyl compounds arising out of the glycol bond fission while the other diols give the hydroxycarbonyl compounds. The reaction is first-order with respect to BTMAB. Michaelis-Menten type kinetics is observed with respect to diol. Addition of benzyltrimethylammonium chloride does not affect the rate. Tribromide ion is postulated to be the reactive oxidizing species. Oxidation of [1,1,2,2-2 H 4 ] ethanediol shows the absence of a kinetic isotope effect. The reaction exhibits substantial solvent isotope effect. A mechanism involving a glycol-bond fission has been proposed for the oxidation of the vicinal diols. The other diols are oxidized by a hydride ion transfer to the oxidant, as are the monohydric alcohols.

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Section: Discussionmentioning

confidence: 99%

Kinetics and mechanism of the oxidation of some diols by benzyltrimethylammoniumtribromide

2001

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“…Since thiosulfonates were being investigated as organic analogues of thiosulfate, we investigated whether oxidation could proceed via a radical mechanism, as has been shown to occur for thiosulfate with a variety of oxidants. [40][41][42][43][44][45][46] Pulse radiolysis was considered an ideal technique for this purpose as it can produce hydroxyl radicals at various concentrations, and any transients formed thereafter can be followed by changes to the UV-visible spectrum. Competition kinetics with thiocyanate were used to determine the rate of the reaction of hydroxyl radicals with thiosulfonates, as the reaction product does not absorb appreciably in the accessible spectral range (typically 300-500 nm).…”

Section: Pulse Radiolysis Studiesmentioning

confidence: 99%

“…27,31,[36][37][38][39] Herein, we report the synthesis and X-ray crystal structures of two sodium thiosulfonate salts, NaMeC 6 H 4 S 2 O 2 and NaPhS 2 O 2 •1.5H 2 O, which have been found to exhibit interesting molecular and supramolecular structural features that influence the sodium coordination environment and contribute to the stabilization of the crystal lattice. Additionally, pulse radiolysis studies of thiosulfonate salts were carried out to establish whether thiosulfonates form radical anions, the impetus being previous pulse radiolysis studies of thiosulfate which have established the formation of radical anions (S 2 O 3 ∑and S 4 O 6 3∑-) from the one-electron oxidation of thiosulfate [40][41][42] and are thought to be intermediates in many kinetic processes involving thiosulfate. [43][44][45][46][47]…”

Section: Introductionmentioning

confidence: 99%

Sodium thiosulfonate salts: Molecular and supramolecular structural features and solution radiolytic properties

Fischmann

Spiccia

2011

Dalton Trans.

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Three sodium thiosulfonate salts, NaMeS(2)O(2)·H(2)O, NaPhS(2)O(2) and NaMeC(6)H(4)S(2)O(2) have been prepared by the direct reaction of the sodium sulfinate salts with elemental sulfur, a clean, benign route that produces no by-products. The structures of the phenyl (which crystallised as a hydrate, NaPhS(2)O(2)·1.5H(2)O) and p-tolyl compounds were determined by X-ray crystallography. For the p-tolyl derivative, NaMeC(6)H(4)S(2)O(2), the unexpected coordination of the pendant sulfur atom was found, a feature not reported previously for thiosulfonate salts, and observed only in two of the more common thiosulfate salts. Intermolecular CH/π interactions are postulated to contribute to the driving force of sulfur coordination, otherwise a different orientation of the aromatic rings would be expected. For NaPhS(2)O(2)·1.5H(2)O, the water ligands and thiosulfonate anions each contribute three oxygen atoms to form a NaO(6) coordination sphere. The thiosulfonate and water oxygens bridge to other sodium atoms forming a three-dimensional layer structure consisting of sheets of NaPhS(2)O(2)·1.5H(2)O with a hydrophilic interior layer, comprising the sodium ions, water ligands and -S(2)O(2)(-) groups, and a hydrophobic exterior formed by the phenyl substituent. The structure is further stabilised by an extensive H-bonding network between the ligated water and the non-coordinating thiosulfonate sulfur atom forming part of the hydrophilic layer and by weak intermolecular edge-to-face CH/π interactions between the sheets. Investigation of the radical chemistry of the three salts using pulse radiolysis indicated that oxidation of NaMeS(2)O(2)·H(2)O involves formation of a sulfur-centred radical rather than hydrogen abstraction from the methyl substituent, whereas oxidation of the aromatic ring is the preferred pathway for the phenyl and p-tolyl derivatives.

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“…A hydrogen abstraction mechanism leading to the formation of free radicals may be discounted in view of the failure to induce polymerization of acrylonitrile 18 and the large values of the reaction constants.…”

Section: Mechanismmentioning

confidence: 99%

Kinetics and mechanism of the oxidation of some α-hydroxy acids by hexamethylenetetramine-bromine

Garg

Kothari

2004

J Chem Sci

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The oxidation of lactic acid, mandelic acid and ten monosubstituted mandelic acids by hexamethylenetetramine-bromine (HABR) in glacial acetic acid, leads to the formation of the corresponding oxoacid. The reaction is first order with respect to each of the hydroxy acids and HABR. It is proposed that HABR itself is the reactive oxidizing species. The oxidation of α-deuteriomandelic acid exhibits the presence of a substantial kinetic isotope effect (k H /k D = 5⋅91 at 298 K). The rates of oxidation of the substituted mandelic acids show excellent correlation with Brown's σ + values. The reaction constants are negative. The oxidation exhibits an extensive cross conjugation between the electron-donating substituent and the reaction centre in the transition state. A mechanism involving transfer of a hydride ion from the acid to the oxidant is postulated.

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Pulse radiolysis of aqueous solutions of thiosulphate

Cited by 21 publications

References 5 publications

Kinetics and mechanism of the oxidation of some diols by benzyltrimethylammoniumtribromide

Kinetics and mechanism of the oxidation of some diols by benzyltrimethylammoniumtribromide

Sodium thiosulfonate salts: Molecular and supramolecular structural features and solution radiolytic properties

Kinetics and mechanism of the oxidation of some α-hydroxy acids by hexamethylenetetramine-bromine

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