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We have studied the electromembrane method for obtaining H3PW12O40. using31P,183W and17O NMR, we have studied the conversions of isopoly-and heteropolytungstates over a broad pH range. Depending on the acidity of the medium and the form of the isopolytungstate, we propose two schemes for reaction of isopolytungstates with phosphate ions during formation of H3PW12O40.

By the oxidation of raesitylene by hydrogen peroxide in AcOH-Ac2O-H2SO4 one can obtain mesitol (2,4,6-trimethylphenol) (with a selectivity of 57–69% at a mesitylene conversion of 22–16% and the acetate of mesitol with a selectivity of 72–85% at 25–22% conversion. The peroxide responsible for the oxidation of mesitylene in this system is in the form of peracetic acid, formedin situ. Over the concentration range studied, the reaction is first order in AcOOH, mesitylene, and H2SO4. Hydroxylation of mesitylene by AcOOH proceeds by an electrophilic substitution mechanism, the limiting step being the formation of the σ-complex.

Ionexchange and electrochemical methods of preparing the heteropolyacid H3PW12O40 are studied. Conditions are found for preparing H3PW12O40 in quantitative yield using electrodialysis without ether extraction.

heteropoly compounds in acetic acid solution oxidize methylbenzenes to form mixtures of aromatic alcohols, aldehydes, di- and polyarylmethanes. The reaction may be carried out catalytically in the presence of oxygen. Results were obtained indicating the formation of an intermediate radical-cation.

The kinetics of hydrogen sulfide oxidation in aqueous solution have been studied in the presence of 12-molybdovanadophosphate heteropolyanions at pH 3.0. The reaction rate obeys the Michaelis equation. Under these conditions the actual oxidant is the isopolyanion that is present in solution in equilibrium with the heteropolyanion.

1. It is found that the reaction of VO2+ with phosphorus-molybdenum-vanadium heteropoly anions (HPAN-n, n=0-6) at pH 2.2–3.0 obeys the kinetic equation v=k' [HPAN-n] [VO2+]/ [H+]α, whereαa=1.5 for HPAN-0 and 1.8 for HPAN-1, and that it includes the formation of an intraspherical intermediate complex [(HPAN-n), VO2+]. 2. The reactivity of HPAN-n varies in the following order: HPAN-0 > HPAN-1 > HPAN-2 < HPAN-3 < HPAN-4 < HPAN-5 < HPAN-6.

1. The oxidation of methylbenzenes (toluene, p-xylene, mesitylene, durene) by palladium- (II) to diarylmethanes in CF3COOH proceeds according to a mechanism of one-electron transfer. In addition, there is an oxidation of arenes to diaryls according to the well-known two-electron mechanism, including electrophilic substitution in the ring of the arene. 2. The contribution of the one-electron mechanism increases with decreasing ionization potential of the arene and with increasing acidity of the medium. 3. Complexes of palladium(I) (probably dimers) are intermediates of the one-electron oxidation of methylbenzenes to diarylmethanes.

The authors investigate the kinetics and mechanism of oxidation of blues Hi[H3+nPMO12−nVn−1VViIVO40] (n=2–6, i) by oxygen in aqueous solution and show that under these conditions the reaction takes place mainly by transfer of three electrons in the complex of oxygen with the blue.

The kinetics of the reactions of VO2+ with 12-tungstovanadophosphates (HPA) in aqueous solution are fully analogous with the kinetics of the reactions of VO2+ with 12-molybdovanadophosphates. The obtained data support the electron transfer mechanism for the reactions of the HPAs with VO2+.

1. The authors have measured the electrical conductivity of heteropoly acids (HPA.) based on Mo(VI), W(VI), and V(V) with heteroatoms P and Si in acetone and acetic acid at 25°C. In acetone, H3PW12O40 and H4PW11VO40 are partially dissociated 3−1 electrolytes. In acetic acid, all the HPA investigated are 1-1 electrolytes. 2. Using the Fuoss-Edelson and Fuoss-Kraus methods they have calculated the thermodynamic dissociation constants and the limiting mobilities of HPA.

Oxidation of xylenes with Pd(II) complexes in acidic medium is possible according to two pathways: a) electrophilic substitution in the arene ring with the formation of an organometalic intermediate and b) one-electron transfer from the arene to the palladium atom with the intermediacy of the arene cation-radical. The relative contribution of each pathway depends on the nature of the arene and on the acidity of the medium.

1. Silicotungstic heteropolyacid is sorbed by silica gels, activated charcoal, and γ-Al2O3 from water and from organic oxygen-containing solvents, forming three formations distinguishable by electron microscopy. 2. The relative proportions of the surface forms are determined by the type of substrate, solvent, and the HPA concentrations on the substrate. The most uniform covering is achieved when HPA is adsorbed from ethyl acetate.

1. In a kinetic study of the interaction of the heteropolyanion PW12O403− with the cations Z=VO2+, VO2+, Fe2+, Fe3+, and MoO22+ in aqueous solution, leading to the replacement of W(VI) by Z, it has been shown that the reaction includes monomolecular and bimolecular pathways. 2. The kinetic data indicate the formation of an intermediate PW12·Z in the bimolecular pathway. 3. The rate constants along both pathways and the constant for formation of the intermediate have been determined, as well as the temperature dependences of these constants.

1. Data on the thermodynamics of the oxidation of 12-molybdovanadophosphate blues by oxygen indicate a low probability for one-electron transfer in the reaction of the blue with oxygen and are consistent with the transfer of two, three, or four electrons. 2. Data on the kinetics of the oxidation of the blues by hydrogen peroxide and oxygen confirm the previously proposed mechanism for the oxidation of weakly reduced blues by oxygen, including the transfer of three electrons in the complex of 02 with the blue.

A study has been made of the kinetics and equilibrium of the reaction of electron transfer between VIV and VV in 12-series heteropolyanions and in the reaction of dissociation of VIV from the HPA.

1. The authors measure the electrical conductivities of heteropoly acids (HPA) of the compositions H3PMo12O40, H4PMo11VIMoVO40, H4PMo11VO40, H4SiMo12O40 and H4SiW12O40 in ethanol and acetone at 25°C. In the concentration range 10−5−10−3 mole/liter, all the HPA are partly dissociated 2−1 electrolytes; dissociation to the third and fourth degree is not manifested. 2. Using the Fuoss-Edelson method, they calculate the thermodynamic dissociation constants K2 and the limiting mobilities of the HPA.

The tungsten heteropoly acids in acetic acid are the most active in the dealkylation of 4-alkyl-2,6-di-tert-butylphenols. The reaction is first order with respect to the substrate and with respect to the HPA, and water slows the reaction. It has been postulated that the dealkylation reaction is mediated mainly by the undissociated molecules of the HPA.

The oxidation of pseudocumene in the benzene nucleus can be effected in HOAc solution by using inorganic oxidizing agents containing oxygen, such as NaNO3, hetero-polyacids, O2, Na2S2O8 and H2O2, with Pd(OAc)2 as catalyst. Na2S2O8 and H2O2 are the most effective, being also active in the absence of Pd(II).

1. The catalytic activity of heteropoly acids (HPA) in the reaction for the electrophilic addition of AcOH to 1-hexene is slightly dependent on the composition of the HPA and substantially exceeds the activity of H2SO4. The catalytic activity correlates with the dissociation constants of the acids. 2. The activity of the W HPA is higher than that of the Mo HPA due to the reduction of the Mo HPA during reaction, which leads to a decrease in their dissociation constants.

1. Depending on the pH, the radiation reduction of concentrated aqueous solutions of the Na salts of HPA of composition Na6H3PMo6V6O40 using γ radiation leads to either vanadium(IV) aqua complexes or polyanions, both of which contain vanadium(IV). 2. The temperature dependence of the recombination of the radicals, generated by γ irradiation, in frozen aqueous HPA solutions indicates the more stable structure of such solutions when compared with ice.

The authors have measured the Hammett acidity functions H0 of concentrated solutions of H3PW12O40 in water, aqueous dioxane, and acetic acid. In these solvents the acidity of H3PW12O40 is higher than those of sulfuric and hydrochloric acids.