V. F. Odyakov

Catalytic oxidation of organic compounds with oxygen in the presence of Mo-V-phosphoric heteropoly acid solutions

The studies carried out at the Institute of Catalysis, Siberian Branch, Russian Academy of Sciences, on the selective catalytic oxidation of organic compounds with oxygen in the presence of aqueous solutions of Mo-V-phosphoric heteropoly acids (HPAs) are reviewed. Alkylphenols are oxidized into 1,4-quinones with a selectivity of 85–99%, and C2-C4 olefins in the presence of Pd complexes are oxidized into carbonyl compounds with a selectivity of 98–99%. The bifunctional (acidic and oxidizing) properties of HPA solutions were used for the first time to synthesize anthraquinones and vitamin K3.

Kinetics of the oxidation of reduced Mo-V-phosphoric heteropoly acid species with dioxygen in concentrated aqueous solutions

Concentrated (0.2 M) aqueous solutions of HP-acids, such as H3+x+mPVIVmVVx-mMo12-xO40 and their analogues with an excess VO2+ cation, are oxidized by dioxygen at 343 K and atmospheric pressure through intermediate active complexes (IAC) [Hx+m-1PVIVmVVx-mMo12-xO404-] · [VO2+]y · O2, where m + y ≥ 3. The electron transfer to the coordinated O2 molecule inside AC is the limiting stage at high m. At low m, the formation of IAC becomes the limiting stage that results in a sharp decrease in the oxidation rate.

Aqueous Solutions of Mo‐V‐Phosphoric Heteropoly Acids as Bifunctional Catalysts For Preparation of 9,10‐Anthraquinone and its Hydrogenated Derivatives

Acid‐catalyzed condensation of 1,3‐butadiene with para‐quinones and oxidation of resulting adducts can be performed as a one‐pot process in the presence of aqueous solutions of Mo‐V‐phosphoric heteropoly acids (HPA) with the general formula HaPzMoyVxOb. These solutions have bifunctional catalytic properties; they are both strong Brønsted acids and reversible oxidants. Condensation of hydroquinone, 1,4‐benzoquinone, or 1,4‐naphthoquinone with 1,3‐butadiene in the HPA solutions results in 9,10‐anthraquinone (AQ) in a mixture with tetrahydro‐AQ (THA) and dihydro‐AQ (DHA). In this one‐pot process, which proceeds in the absence of organic solvents, the HPA solution is reduced. A slightly soluble mixture of THA, DHA, and AQ is precipitated and filtered off. The non‐Keggin‐type H12P3Mo18V7O85 solution is the most effective in this process. This solution can be rapidly regenerated by dioxygen or air at temperatures of up to 170 °C and then reused. The prepared THA+DHA+AQ mixture can be used as a catalyst for alkaline delignification of wood. Our homogeneous bifunctional HPA catalyst is very stable and promising for use in similar one‐pot processes.

Kinetics of oxidation of butene-1 to butanone in aqueous solution in the presence of ions Pd2+ and Mo-V-phosphoric heteropoly acid

Oxidation of butene-1 to butanone in the presence of homogeneous catalysts (PdSO4 + HPA-x), where HPA-x = H3+xPVxMo12-xO40, 1 £ x £ 4, was investigated. This reaction is found to be of the 1st order with respect to C4H8, and of the 0.64th order with respect to Pd. The reaction rate does not depend on the HPA-x concentration and pH of the solution. The activation energy of the reaction is variable. A kinetic expression of the reaction is obtained for 303-343 K.

New catalytic method for the synthesis of vitamins K

A new catalytic method for the synthesis of vitamins of the K family is suggested. In this method 2-methyl-1-naphthol is oxidized by dioxygen in the presence of Mo-V-P heteropoly acids or their salts in a two-phase system (organic solvent + water) to 2-methyl-1,4-naphthoquinone or vitamin K3, which is the precursor of all K family vitamins.

Phase-transfer oxidation of 2-methyl-1-naphthol into 2-methyl-1,4-naphthoquinone in the presence of vanadomolybdophosphoric heteropolyacids

Abstract2-Methyl-1-naphthol is oxidized into 2-methyl-1,4-naphthoquinone (menadione) by air in the presence of vanadomolybdophosphoric heteropolyacids and their salts. The reaction proceeds in a biphasic system, and the yield of menadione is up to 85 %. The influence of the composition of the heteropolyacids on the rate and the selectivity of the reaction was studied, and the reaction mechanism was proposed.

Kinetics and mechanism of the homogeneous oxidation of n-butenes to methyl ethyl ketone in a solution of Mo-V-phosphoric heteropoly acid in the presence of palladium pyridine-2,6-dicarboxylate

In catalytic two-step n-butene oxidation with dioxygen to methyl ethyl ketone, the first step is the oxidation of n-C4H8 with an aqueous solution of Mo-V-P heteropoly acid in the presence of Pd(II) complexes. The kinetics of n-butene oxidation with solutions of H7PV4Mo8O40 (HPA-4) in the presence of the Pd(II) dipicolinate complex (H2O)PdII(dipic) (I), where dipic2− is the tridentate ligand 2,6-NC5H3(COO−)2, is studied. Calculation shows that, at the ratio dipic2−: Pd(II) = 1: 1, the ligand decreases the redox potential of the Pd(II)/Pdmet system from 0.92 to 0.73–0.77, due to which Pd(II) is stabilized in reduced solutions of HPA-4. The reaction is first-order with respect to n-C4H8. Its order with respect to Pd(II) is slightly below unity, and its order with respect to HPA-4 is relatively low (∼0.63). The activation energy of but-1-ene oxidation in the temperature range from 40 to 80°C is 49.0 kJ/mol, and that of the oxidation of but-2-ene is 55.6 kJ/mol. The mechanism of the reaction involving the cis-diaqua complex [(H2O)2PdII(Hdipic)]+, which forms reversibly from complex I, is proposed. The reaction rate is shown to increase with an increase in the HPA-4 concentration due to an increase in the acidity of the solution.

NEW CATALYTIC METHODS FOR THE SYNTHESIS OF VITAMINS K : K3, K4 AND VIKASOL

A series of catalysts is developed for synthesis of vitamins K from easily available l-naphthol. The corresponding catalytic reactions compose the background of VIKASIB technology, which is friendly to the enviroment.

Homogeneous redox catalysts based on heteropoly acid solutions: I. Pilot testing of a catalyst and methyl ethyl ketone synthesis

The pilot experiments on methyl ethyl ketone (MEK) synthesis in 2005–2006 were aimed at developing a technology for highly selective n-butylene oxidation with oxygen into MEK in the presence of a new homogeneous catalyst. This catalyst was a chloride-free aqueous solution of Pd(II) + HPA-7′, where HPA-7′ is a vanadium-rich molybdovanadophosphoric acid of modified (non-Keggin) composition with the empirical formula H12P3Mo18V7O85. For ensuring the explosion and fire safety of the pilot unit, the MEK synthesis process was carried out in two steps conducted in different reactors. The catalyst solution in the pilot plant circulated in a closed loop. The target reaction (step (1)) was performed at 60°C and an n-butylene pressure of 9 bar in a tubular plug-flow reactor 1 in the absence of O2. The high oxidation potential of the HPA-7′ solution ensured a high rate of the reaction, which lasted <20 min. The separation of MEK from the reduced catalyst was carried out in a film evaporator (stripping column) at 100°C. Subsequent catalyst regeneration with atmospheric oxygen (step (2)) was performed in an original perfect-mixing reactor 2. At 160–190°C and a pressure of 20 bar (

New Route to Vicasol, a Water-Soluble Form of Vitamin K3

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