Kinetics of the Epoxidation of Crotonic Acid by Aqueous Hydrogen Peroxide Catalysed by Sodium Orthovanadatae

2012 ◽  
Vol 28 (3) ◽  
pp. 1475-1478
Author(s):  
J.V. SINGH ◽  
ANUPAM AWASTHI ◽  
DIPTI DIPTI ◽  
ASHISH TOMAR ◽  
DAVENDRA SINGH ◽  
...  
1981 ◽  
Vol 59 (4) ◽  
pp. 718-722 ◽  
Author(s):  
Yoshiro Ogata ◽  
Kazushige Tanaka

The oxidation of dimethyl sulfoxide (DMSO) by hydrogen peroxide in the presence of a catalytic amount of sodium tungstate (Na2WO4) has been studied kinetically by means of iodometry of hydrogen peroxide. The reaction is first-order with respect to the substrate and the catalyst, but independent of the concentration of hydrogen peroxide which is present in excess of the catalyst. The polarographic study implies that in solutions two main kinds of peroxytungstic acids (H2WO5 and H2WO8) are formed which contain active oxygen in ratios (active oxygen):(Na2WO4) of 1:1 and 4:1, respectively. The effect of acidity on the oxidation rate and a probable mechanism involving a rate-determining attack of peroxytungstic acids are discussed.


Author(s):  
Anton A. Chumakov ◽  
Oleg A. Kotelnikov ◽  
Yurij G. Slizhov ◽  
Tamara S. Minakova

There are actuality and importance of confirmation or at least reasoned argumentation of molecular kinetics of hydrogen peroxide oxidation reactions because of currently unidentified true nature of oxygen intermediates, at one side, and widespread of these processes in natural biological and artificial anthropogenic systems, from other side. The building of common theory of hydrogen peroxide oxidative activity and dismutation decomposition can be based on determination of structure of individual model reactions products. The benzylpenicillin molecule has a heterofunctional structure. Its sodium salt was dissolved in aqueous hydrogen peroxide solution without Fenton catalysts addition. The system was protected from thermal and photochemical activation. As result, we observed a colloid solution formation, a water-insoluble sediment accumulation, and a hydrogen peroxide disproportionation with gas-phase molecular oxygen liberation. The NMR-spectroscopy data evidenced in favor of S-oxidation of sulfide fragment, N-oxidation of nitrogen atoms with amide groups dissociation, and aromatic ring hydroxylation and electrophilic carbonylation. The precipitate is a mixture of several substances, some of which have presumably an oligomeric structure due to neighboring molecules coupling in carbonylation and hydroxylamine fragments O-acylation reactions. The molecular kinetics of model organic molecule oxidative modifications and hydrogen peroxide dismutation is interpreted by oxywater-oxenoid conception. In accordance with one, there are different associates between water HOH and hydrogen peroxide HOOH molecules in solution system due to hydrogen bonds. These molecules are simultaneously Brønsted acids and bases. The rate of proton accepting and donation depends on temperature and concentration parameters. The hydronium H3O+ and hydroperoxonium H3O2+ cations, and the hydroxide HO− and hydroperoxide HO2− anions are generated. For hydrogen peroxide molecule H2O2, there is possibility for isomeric bipolar ion oxywater H2O+O− formation. The zwitter-ion heterolytically dissociates with water molecule liberation and singlet oxygen atom generation. The 1D-oxene (2p[↑↓][↑↓][_]) oxidizes sulfur and nitrogen heteroatoms through accepting their unshared electron pairs by own vacant atomic orbital. In addition, singlet oxygen atom hydroxylates an aromatic ring by hydride transfer and mediates decomposition of hydrogen peroxide. The dioxygen liberated during hydrogen peroxide dismutation is generated at first in singlet 1∆g-quantum state, the quenching of which, presumably, includes a dimerization of 1O2 antipodes by orbital moment. Inside the associate (1O2)2, the electron exchange interaction occurs. As result, two molecules of triplet dioxygen are generated, and they are antipodes by spin moment: first molecule has spin +1 and second molecule has spin −1.


1996 ◽  
Vol 61 (10) ◽  
pp. 1457-1463 ◽  
Author(s):  
Vladimír Mošovský ◽  
Zuzana Cvengrošová ◽  
Alexander Kaszonyi ◽  
Milan Králik ◽  
Milan Hronec

Oxidation kinetics of formic acid with aqueous hydrogen peroxide (30-70%) has been studied at 45 °C with 0-0.1 M H2SO4 as a catalyst. A kinetic model has been suggested which satisfactorily describes the oxidation process of formic acid to peroxyformic acid.


2015 ◽  
Vol 55 (1) ◽  
pp. 51-56 ◽  
Author(s):  
A. E. Meshechkina ◽  
L. V. Mel’nik ◽  
G. V. Rybina ◽  
S. S. Srednev ◽  
Yu. A. Moskvichev ◽  
...  

2014 ◽  
Vol 27 (4) ◽  
pp. 213-216 ◽  
Author(s):  
Maria Zun ◽  
Dorota Dwornicka ◽  
Katarzyna Wojciechowska ◽  
Katarzyna Swiader ◽  
Regina Kasperek ◽  
...  

Abstract In this study, the stability of 10% hydrogen peroxide aqueous and non-aqueous solutions with the addition of 6% (w/w) of urea was evaluated. The solutions were stored at 20°C, 30°C and 40°C, and the decomposition of hydrogen peroxide proceeded according to first-order kinetics. With the addition of the urea in the solutions, the decomposition rate constant increased and the activation energy decreased. The temperature of storage also affected the decomposition of substance, however, 10% hydrogen peroxide solutions prepared in PEG-300, and stabilized with the addition of 6% (w/w) of urea had the best constancy.


Catalysts ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 283
Author(s):  
Oxana Kholdeeva ◽  
Nataliya Maksimchuk

In recent years, metal–organic frameworks (MOFs) have received increasing attention as selective oxidation catalysts and supports for their construction. In this short review paper, we survey recent findings concerning use of MOFs in heterogeneous liquid-phase selective oxidation catalysis with the green oxidant–aqueous hydrogen peroxide. MOFs having outstanding thermal and chemical stability, such as Cr(III)-based MIL-101, Ti(IV)-based MIL-125, Zr(IV)-based UiO-66(67), Zn(II)-based ZIF-8, and some others, will be in the main focus of this work. The effects of the metal nature and MOF structure on catalytic activity and oxidation selectivity are analyzed and the mechanisms of hydrogen peroxide activation are discussed. In some cases, we also make an attempt to analyze relationships between liquid-phase adsorption properties of MOFs and peculiarities of their catalytic performance. Attempts of using MOFs as supports for construction of single-site catalysts through their modification with heterometals will be also addressed in relation to the use of such catalysts for activation of H2O2. Special attention is given to the critical issues of catalyst stability and reusability. The scope and limitations of MOF catalysts in H2O2-based selective oxidation are discussed.


Sign in / Sign up

Export Citation Format

Share Document