RU2681950C1 - Catalyst, method for preparation thereof and method for preparation of substituted quinones - Google Patents

Abstract

FIELD: chemistry.SUBSTANCE: invention relates to a method for producing substituted quinones, including 2,3,5-trimethyl-1,4-benzoquinone (TMBQ), a key intermediate in the synthesis of vitamin E, widely used in medical practice and animal husbandry, as well as to the synthesis of catalysts for this method. Catalyst is described for the process of producing substituted quinones by oxidizing aromatic compounds with hydrogen peroxide, including vanadium-containing polyoxotungstate TBAH[γ-PVWO], where n=1, mounted on a solid carrier - nitrogen-containing carbon material, which is a nanotube or nanofibres, the content of polyoxotungstate in the catalyst is 5–25 wt. %. Method of preparation of this heterogeneous catalyst is that a carrier - nitrogen-containing carbon material - is added to the solution of polyoxotungstate in acetonitrile, which is a nanotube or nanofibres, and mineral acid, the resulting catalyst is separated by filtration from the solution and dried. Method for producing substituted quinones by oxidation of aromatics with hydrogen peroxide in the presence of the catalyst described above, including vanadium-containing polyoxotungstate, is also proposed TBAH[γ-PVWO], where n=1, in the environment of the aromatic solvent - acetonitrile.EFFECT: creation of an effective heterogeneous catalyst for the oxidation of substituted phenols to quinones, a high-tech method for its preparation and the catalytic method of oxidation of substituted phenols to quinones using a cheap and environmentally friendly oxidant - hydrogen peroxide.13 cl, 1 dwg, 2 tbl, 38 ex

Description

The invention relates to a method for producing substituted quinones, including 2,3,5-trimethyl-1,4-benzoquinone (TMBH), a key intermediate in the synthesis of vitamin E, widely used in medical practice and animal husbandry, and also to the synthesis of catalysts for of this method.

The methods for producing alkyl substituted quinones from the corresponding alkyl phenols are divided into three main groups: 1) stoichiometric oxidation with inorganic oxidizing agents - manganese (IV) and chromium (VI) compounds, nitric acid, etc., 2) homogeneous catalytic oxidation in the presence of transition metal complexes, and 3) heterogeneous catalytic oxidation in the presence of solid phase transition metal catalysts. Stoichiometric oxidation uses large amounts of expensive and toxic oxidizing agents, which leads to problems associated with the disposal of large amounts of toxic waste. Therefore, catalytic methods of oxidation are much more acceptable both from an environmental point of view and from an economic point of view. Of greatest interest are the catalytic methods for producing quinones from substituted phenols, based on the use of environmentally friendly oxidizing agents (molecular oxygen and hydrogen peroxide), which give water as the only by-product [O.A. Kholdeeva, O.V. Zalomaeva, Recent advances in transition-metal catalyzed selective oxidation of phenols and methoxyarenes using environmentally benign oxidants, Coord. Chem. Rev. 306 (2016) 302-330]. Although the cost of hydrogen peroxide is higher than the cost of oxygen, in small tonnage processes of fine organic synthesis the use of the former is often preferable, since the cost of technological equipment for hydrogen peroxide oxidation is lower than for oxygen oxidation [R.A. Sheldon, J. Dakka. Heterogeneous catalytic oxidations in the manufacture of fine chemicals. Catalysis Today 19 (1994) 215].

In the oxidation of substituted phenols with oxygen, three main types of homogeneous catalysts are used: 1) complexes of cobalt with Schiff bases [L. Schuster, N. Pommer, DE 1793183 (1968)], 2) copper halides [EP 0093540, C07C 50/04, 1983; EP 0127888 B1, C07C 46/08, 1987] and 3) phosphormolybdovanadium heteropoly acids H _{3 + n} PMo _12-n V _n O ₄₀ (GPC-n, n = 2-6) [SU 1719392, C07C 50/04, 1991; PCT / FR 96/01689, C07C 46/08; RU 2022958, C07C 50/12, 1994; WO 2004/014832]. Catalysts based on cobalt complexes with organic ligands (Schiff bases) are subject to oxidative degradation and have low productivity. The disadvantages of catalytic methods based on the use of copper halides are high (practically stoichiometric) amounts of catalyst and product contamination with a toxic transition metal, as well as equipment corrosion. In addition, in the case of the use of copper chlorides, side formation of toxic organochlorine compounds occurs. Even the use of two-phase water-organic solvent systems [US Pat. 5041572, 1991] does not completely avoid contamination of the product with traces of the transition metal. Methods based on the use of HPA-n also use close to stoichiometric amounts of catalyst, and the product is contaminated with transition metals.

, K., Wienhcfer, G., Schrcder, K., Join, В., Junge, K., Beller, M. Chem. Eur. J. 2010, 16, 10300], а также гетерополикислот структуры Кеггина (H_nXM₁₂O₄₀, X=Si (n=4), Р (n=3); М=Мо, W) [US 5245059, C07C 50/04, 1993]. В качестве гетерогенных катализаторов могут быть использованы различные мезопористые материалы, содержащие медь [US Patent 6500972 (2002)] и титан [US 5712402, С07С 50/02, 1998; RU 2164510, 2000; 2196764, 2001].For oxidation of substituted phenols with hydrogen peroxide, systems based on the use of ruthenium and iron compounds as a homogeneous catalyst [Ito S., Aihara K., Matsumoto M. Tetr. Lett. Ruthenium-catalyzed oxidation of phenols with hydrogen peroxide. 24 (1983) 5249; Wienhcfer G., Schrcder K., Mcller K., Junge K., Beller M. Adv. Synth. Catal. 2010, 352, 1615;

, K., Wienhcfer, G., Schrcder, K., Join, B., Junge, K., Beller, M. Chem. Eur. J. 2010, 16, 10300], as well as heteropoly acids of the Keggin structure (H _n XM ₁₂ O ₄₀ , X = Si (n = 4), P (n = 3); M = Mo, W) [US 5245059, C07C 50 / 04, 1993]. As heterogeneous catalysts, various mesoporous materials containing copper [US Patent 6500972 (2002)] and titanium [US 5712402, C07C 50/02, 1998; RU 2164510, 2000; 2196764, 2001].

The disadvantages of the above catalyst systems are, as a rule, the insufficiently high yield of the target product and, consequently, the need for the cost of purification from by-products, as well as the low efficiency of the use of the oxidizing agent (selectivity for hydrogen peroxide) due to the side process of its decomposition on the catalyst.

Closest to this invention is a method for the oxidation of substituted phenols to quinones with hydrogen peroxide in the presence of a homogeneous catalyst - alkyl ammonium salts of vanadium-containing polyoxotungstate (Alk _mn H _n ) [γ-PV ₂ W ₁₀ O ₄₀ ], Alk = (C _k H _{2k + 1} ) ₄ N, k = 4-6; m is 5; n = 0-2) (Pat. RF, No. 2568645, C07C 50/04, B01J 23/22, 11/20/2015). The synthesis of compounds of this type is described in [K. Kamata, K. Sugahara, K. Yonehara, R. Ishimoto, N. Mizuno, Chem. Eur. J. 2015, 17, 7549; O.V. Zalomaeva, V.Yu. Evtushok, GM Maksimov, RI Maksimovskaya, OA Kholdeeva, Dalton Transactions, 2017, 46, 5202]. The disadvantage of this method is the difficulty of separating the catalyst from the reaction products, since both the catalyst and the products are dissolved in one phase. In addition, when using a homogeneous catalyst, contamination of the product with transition metals (W, V) is possible.

According to a method for preparing a catalyst, the closest to the present invention is a method for producing a composite heterogeneous catalyst based on vanadium-containing polyoxotungstate TBA _5-n H _n [γ-PV ₂ W ₁₀ O ₄₀ ], comprising preparing a solution of TBA _5-n H _n [γ-PV ₂ W ₁₀ O ₄₀ ] with co-catalysts TBA ₄ [SiW ₁₂ O ₄₀ ] and HClO ₄ and applying the resulting mixture to Fe ₂ O ₃ [Wang, Y .; Kamata, K .; Ishimoto, R .; Ogasawara, Y .; Suzuki, K .; Yamaguchi, K .; Mizuno N. Catal. Sci. Technol. 2015, 5, 2602-2615]. This type of catalyst was used for epoxidation of alkenes, sulfoxidation of thioesters and hydroxylation of anisole, but was not used to oxidize alkyl phenols to quinones [Wang, Y .; Kamata, K .; Ishimoto, R .; Ogasawara, Y .; Suzuki, K .; Yamaguchi, K .; Mizuno N. Catal. Sci. Technol. 2015, 5, 2602-2615]. The disadvantages of this method of preparation of the catalyst are the complexity of the synthesis technology (the need to use an additional component - TBA ₄ [SiW ₁₂ O ₄₀ ]), the use of iron oxide as a carrier (it may be unproductive decomposition of hydrogen peroxide, which leads to a decrease in the efficiency of using an oxidizing agent), decrease in catalyst activity during repeated use, as well as instability of the catalyst obtained by this method in polar solvents, for example, acetonitrile, application which are necessary for the oxidation of alkyl phenols to quinones.

The objective of the invention is to provide an effective heterogeneous catalyst for the oxidation of substituted phenols to quinones, a high-tech method for its preparation and a catalytic method for the oxidation of substituted phenols to quinones using a cheap and environmentally friendly oxidizing agent - hydrogen peroxide.

Technical result:

- high activity and selectivity of a heterogeneous catalyst that does not lose activity and selectivity with repeated use,

- the method of preparation of the catalyst allows 1) to fix the active component (vanadium-containing polyoxotungstate) while maintaining its activity and selectivity, and 2) to obtain a catalytically active material resistant to the effects of the polar reaction medium, which can be used repeatedly without loss of catalytic properties,

- simplification and cheapening of the technology of existing processes for producing quinones and increasing the purity of the product by eliminating the formation of toxic chlorine-containing by-products, corrosion of equipment and contamination of the product with transition metals.

The problem is solved in that as a heterogeneous catalyst, tetrabutylammonium salts of vanadium-containing polyoxotungstate (TBA _5-n H _n [γ-PV ₂ W ₁₀ O ₄₀ ] (n = 1-2) are used, fixed on a solid support — nitrogen-containing carbon material, the content of polyoxotungstate in the catalyst is 5-25 wt.%. The nitrogen-containing carbon material may be nanotubes or nanofibers, the nitrogen content in the carrier is 1-5 at.%.

The problem is also solved by the method of preparing a heterogeneous catalyst, including vanadium-containing polyoxytungstate TBA _5-n H _n [γ-PV ₂ W ₁₀ O ₄₀ ], where: n = 1-2, for the process of obtaining substituted quinones by oxidation of aromatic compounds with hydrogen peroxide, which consists in that to a solution in acetonitrile is added polioksovolframata carrier - a nitrogen-containing carbon material and a mineral acid, preferably, HClO _4, the resulting catalyst was separated by filtration from the solution and dried, thereby obtaining a catalyst to tory comprises vanadium polioksovolframat TBA _5-n H _{n [γ-PV 2} W ₁₀ O _40], where: n = 1-2, in an amount of 5-25 wt. %, mounted on a solid carrier - nitrogen-containing carbon material. Before the application process, the nitrogen-containing carbon material is dried in vacuum at a temperature not exceeding 100 ° C.

The problem is also solved by the method of obtaining substituted quinones by oxidation of aromatic compounds with hydrogen peroxide in the presence of a catalyst, including vanadium-containing polyoxungstate TBA _5-n H _n [γ-PV ₂ W ₁₀ O ₄₀ ], where: n = 1-2, in an aromatic solvent - acetonitrile, the catalyst described above is used as a catalyst, the process is carried out at a temperature of at least 25 ° C. As aromatic compounds take substituted phenols, such as 2,3,6-trimethylphenol, 2,6-dimethylphenol and 2,6-ditretbutylphenol. The catalyst is dried before use in vacuum at a temperature of not more than 60 ° C. As an oxidizing agent, an aqueous solution of hydrogen peroxide with a content of hydrogen peroxide of at least 30 wt. %, use a substrate concentration of not higher than 0.15 M, use a molar ratio of hydrogen peroxide / substrate of not less than 2.3, use a molar ratio of substrate / active component of the catalyst of not less than 66, the catalyst is separated by filtration and reused.

The synthesis of nitrogen-containing carbon nanomaterials is described in [Suboch, A.N .; Cherepanova, S.V .; Kibis, L.S .; Svintsitskiy, A.D .; Stonkus, O.A .; Boronin, A.I .; Chesnokov, V.V .; Romanenko, A.I .; Ismagilov, Z.R .; Podyacheva O. Yu. Fullerenes, Nanotub. Carbon Nanostructures 2016, 24, 520-530; Shalagina A.E., Ismagilov Z.R., Podyacheva O.Yu., Kvon R.I., Ushakov V.A. Carbon 2007, 45; 1808-1820]. The active component (polyoxotungstate) is firmly fixed on the surface of the solid support and is not washed out during the liquid phase oxidation with hydrogen peroxide, the catalyst is separated by simple filtration and can be used repeatedly without loss of activity and selectivity.

The invention is illustrated by the following examples, tables.

- без фильтрования, • - катализатор отфильтровывали через 6 мин после начала реакции (условия см. в примере 33).In FIG. The kinetic oxidation curves of 2,3,6-trimethylphenol Н ₂ О ₂ in the presence of γ-PV ₂ W ₁₀ / N-CNT are presented:

- without filtration, • - the catalyst was filtered out 6 minutes after the start of the reaction (for conditions, see Example 33).

Example 1

Before using carbon nanotubes with a nitrogen content of 4.8 at. % (N-CNTs) are dried in vacuum at 110 ° C for 4 hours. 2.8 micromoles of TBA ₄ H [γ-PV ₂ W ₁₀ O ₄₀ ] (γ-PV ₂ W ₁₀ ) are dissolved in 5 ml of dry acetonitrile and with stirring (500 rpm) add 1 equiv. HClO ₄ (2.8 micromoles). To the resulting solution was added 120 mg of 4.8% N-CNT and left for 2 hours with stirring. Then the solid is separated, washed with acetonitrile (3 times 5 ml) and dried in air. The resulting catalyst γ-PV ₂ W ₁₀ /4.8% N-CNT contains 8 wt. % γ-PV ₂ W ₁₀ and 4.8 at. % N. The surface area of the catalyst S (BET) is 147 m ² / g, the pore volume is 0.53 cm ³ / g, and the average pore diameter is 14 nm.

Example 2. The synthesis is carried out as in example 1, but take 9.3 micromoles of γ-PV ₂ W ₁₀ and 9.3 micromoles of HClO ₄ , resulting in a catalyst γ-PV ₂ W ₁₀ / N-CNT containing 25 wt. % γ-PV ₂ W ₁₀ and 4.8 at. % N.

Example 3. The synthesis is carried out as in example 1, but take 5.6 micromoles of γ-PV ₂ W ₁₀ and 5.6 micromoles of HClO ₄ , resulting in a catalyst γ-PV ₂ W ₁₀ / N-CNT containing 15 wt. % γ-PV ₂ W ₁₀ and 4.8 at. % N.

Example 4. The synthesis is carried out as in example 1, but take 3.7 micromoles of γ-PV ₂ W ₁₀ and 3.7 micromoles of HClO ₄ , resulting in a catalyst γ-PV ₂ W ₁₀ / N-CNT containing 10 wt. % γ-PV ₂ W ₁₀ and 4.8 at. % N.

Example 5. The synthesis is carried out as in example 1, but 1.85 micromoles of γ-PV ₂ W ₁₀ and 1.85 micromoles of HClO ₄ are taken, whereby a γ-PV ₂ W ₁₀ / N-CNT catalyst containing 5 wt. % γ-PV ₂ W ₁₀ and 4.8 at. % N.

Examples 1-5 demonstrate the possible range of the weight content of the active component (γ-PV ₂ W ₁₀ ) in the catalyst.

Example 6. The synthesis is carried out as in example 3, but take N-CNTs with a nitrogen content of 3.1 at. %, resulting in a catalyst γ-PV ₂ W ₁₀ / N-CNT containing 15 wt. % γ-PV ₂ W ₁₀ and 3.1 at. % N.

Example 7. The synthesis is carried out as in example 3, but take N-CNTs with a nitrogen content of 1.8 at. %, resulting in a catalyst γ-PV ₂ W ₁₀ / N-CNT containing 15 wt. % γ-PV ₂ W ₁₀ and 1.8 at. % N. The surface area of the catalyst S (BET) 132 m ² / g, pore volume 0.64 cm ³ / g, average pore diameter 19 nm.

Example 8. The synthesis is carried out as in example 3, but take carbon nanotubes not containing nitrogen (CNTs), resulting in a catalyst γ-PV ₂ W ₁₀ / CNT containing 15 wt. % γ-PV ₂ W ₁₀ and 0 at. % N. The surface area of the catalyst S (BET) 145 m ² / g, pore volume 0.64 cm ³ / g, average pore diameter 15 nm.

Examples 3 and 6-8 show that varying the nitrogen content in CNTs does not affect the content of γ-PV ₂ W ₁₀ in the catalyst.

Example 9. The synthesis is carried out as in example 3, but N-CNTs are not preliminarily dried, as a result of which a γ-PV ₂ W ₁₀ / N-CNT catalyst containing 6 wt. % γ-PV ₂ W ₁₀ and 4.8 at. % N.

Example 9 in comparison with example 3 shows that the humidity of the carrier reduces the weight content of γ-PV ₂ W ₁₀ in the catalyst.

Example 10. The synthesis is carried out as in example 3, but HClO _{4 is} not added, as a result of which the content of γ-PV ₂ W ₁₀ in the resulting material is close to 0.

Example 10 in comparison with example 3 shows that the addition of the mineral acid HClO _{4 is} necessary for fixing γ-PV ₂ W ₁₀ to CNTs.

Example 11. The synthesis is carried out as in example 8, but instead of CNTs, carbon nanofibers not containing nitrogen (CNF) are taken. As a result, a γ-PV ₂ W ₁₀ / CNF catalyst containing 15 wt. % γ-PV ₂ W ₁₀ .

This example shows that the morphology of the carbon material does not affect the content of γ-PV ₂ W ₁₀ in the catalyst.

Example 12. The synthesis is carried out as in example 11, but take carbon nanofibers containing 3 at. % nitrogen (N-CNF). As a result, a γ-PV ₂ W ₁₀ / N-CNF catalyst containing 15 wt. % γ-PV ₂ W ₁₀ and 3 at. % N.

Example 13. The synthesis is carried out as in example 11, but take carbon nanofibers containing 6 at. % nitrogen (N-CNF). As a result, a γ-PV ₂ W ₁₀ / N-CNF catalyst containing 15 wt. % γ-PV ₂ W ₁₀ and 6 at. % N.

Examples 11-13 show that the nitrogen content in the CNF also does not affect the content of γ-PV ₂ W ₁₀ in the catalyst.

Example 14. The synthesis is carried out as in example 13, but take 2.8 micromole γ-PV ₂ W ₁₀ . As a result, a γ-PV ₂ W ₁₀ / N-CNF catalyst containing 8 wt. % γ-PV ₂ W ₁₀ and 6 at. % N. The surface area of the catalyst S (BET) 195 m ² / g, pore volume 0.49 cm ³ / g, average pore diameter 10 nm.

Example 15. In a temperature-controlled at 60 ° C glass reactor equipped with a magnetic stirrer, 13.6 mg of 2,3,6-trimethylphenol (TMP) (0.1 mmol), 60 mg of γ-PV ₂ W ₁₀ dried in vacuum at 60 ° С are placed / N-CNT, the synthesis of which is described in example 2 (weight content of γ-PV ₂ W ₁₀ 25 wt.%, Nitrogen content of 4.8 at.%) And 1 ml of acetonitrile. Then, with stirring, 41 μl (0.45 mmol) of 33% H ₂ O ₂ is added. The mixture is stirred vigorously at 60 ° C. After 0.25 h, the conversion of TMP and the yield of 2,3,5-trimethyl-1,4-benzoquinone (TMBH), calculated on the reacted TMP (selectivity) determined by GLC, are 100 and 99%, respectively.

Example 16. The process is carried out as in example 15, but take the catalyst, the synthesis of which is described in example 3 (γ-PV ₂ W ₁₀ 15 wt.%, Nitrogen content 4.8 at.%). After 0.25 h, the conversion of TMP and selectivity for TMBH are 100 and 99%, respectively.

Example 17. The process is carried out as in example 15, but take the catalyst, the synthesis of which is described in example 4 (γ-PV ₂ W ₁₀ 10 wt.%, Nitrogen content 4.8 at.%). After 0.25 h, the conversion of TMP and selectivity for TMBH are 100 and 90%, respectively.

Example 18. The process is carried out as in example 15, but take the catalyst, the synthesis of which is described in example 5 (γ-PV ₂ W ₁₀ 5 wt.%, Nitrogen content 4.8 at.%). After 0.25 h, the conversion of TMP and selectivity for TMBH are 100 and 84%, respectively.

Examples 15-18 shows that the decrease in the weight content of γ-PV ₂ W ₁₀ below 15 wt. % leads to a decrease in the selectivity of the formation of the target product.

Example 19. The process is carried out as in example 15, but take N-CNT with 4.8 at. % N not containing γ-PV ₂ W ₁₀ . After 0.25 h, the conversion of TMP and selectivity for TMBH are 80 and 0%, respectively. This example, in comparison with examples 15-18 shows that not containing γ-PV ₂ W _{10 the} carrier of N-CNTs catalyzes the oxidation of TMF, but the process does not lead to the formation of TMBH.

Example 20. The process is carried out as in example 15, but take the catalyst, the synthesis of which is described in example 6 (γ-PV ₂ W ₁₀ 15 wt.%, Nitrogen content of 3.1 at.%). After 0.25 h, the conversion of TMP and selectivity for TMBH are 100 and 99%, respectively.

Example 21. The process is carried out as in example 15, but take the catalyst, the synthesis of which is described in example 7 (γ-PV ₂ W ₁₀ 15 wt.%, Nitrogen content 1.8 at.%). After 0.25 h, the conversion of TMP and selectivity for TMBH are 100 and 99%, respectively.

Example 22. The process is carried out as in example 15, but take the catalyst, the synthesis of which is described in example 8 (γ-PV ₂ W ₁₀ 15 wt.%, Nitrogen content 0 at.%). After 0.25 h, the conversion of TMP and selectivity for TMBH are 100 and 90%, respectively.

This example, compared with examples 15, 20 and 21, shows that to achieve 99% selectivity, at least 1.8 at. % nitrogen in the carrier.

Example 23. The process is carried out as in example 16, but the catalyst is not dried in vacuum before use. After 0.25 h, the conversion of TMP and selectivity for TMBH are 100 and 82%, respectively.

Example 24. The process is carried out as in example 20, but the catalyst is not dried in vacuum before use. After 0.25 h, the conversion of TMP and selectivity for TMBH are 100 and 90%, respectively.

Example 25. The process is carried out as in example 22, but the catalyst is not dried in vacuum before use. After 0.25 h, the conversion of TMP and selectivity for TMBH are 98 and 86%, respectively.

Examples 23-25 in comparison with examples 16, 20, 22 show that pre-drying the catalyst is necessary to achieve high selectivity for the formation of the target product.

Example 26. The process is carried out as in example 21, but the catalyst is not dried in vacuum before use. After 0.25 h, the conversion of TMP and selectivity for TMBH are 100 and 99%, respectively.

This example shows that drying the catalyst with a content of γ-PV ₂ W ₁₀ 15 wt. % and nitrogen content of 1.8 at. % is not a critical parameter, unlike catalysts with a different nitrogen content.

Example 27. The process is carried out as in example 16, but add 33 μl (0.35 mmol) 33% H ₂ About ₂ . After 0.25 h, the conversion of TMP and selectivity for TMBH are 88 and 97%, respectively.

This example in comparison with example 16 shows that a decrease in the concentration of the oxidizing agent leads to a decrease in the conversion of TMP.

Example 28. The process is carried out as in example 21, but add 33 μl (0.35 mmol) 33% H ₂ About ₂ . After 0.25 h, the conversion of TMP and selectivity for TMBH are 100 and 99%, respectively.

This example in comparison with example 21 and 27 shows that when using a catalyst composition γ-PV ₂ W ₁₀ 15 wt. % and 1.8 at. % nitrogen, it is possible to reduce the concentration of the oxidizing agent without reducing the conversion of TMP since there is an increase in the efficiency of using the oxidizing agent from 50% in Example 21 to 80% in this Example.

Example 29. The process is carried out as in example 28, but take the concentration of TMP 0.15 M. After 0.25 hours the conversion of TMP and selectivity for TMBH are 80 and 95%, respectively, and the efficiency of hydrogen peroxide is 65%.

This example in comparison with example 21 and 28 shows that an increase in the concentration of TMP does not lead to a further increase in the efficiency of use of H ₂ O ₂ .

Example 30. The process is carried out as in example 21, but at a temperature of 50 ° C. After 0.5 h, the conversion of TMP and selectivity for TMBH are 98 and 92%, respectively.

Example 31. The process is carried out as in example 21, but at a temperature of 25 ° C. After 0.66 h, the conversion of TMP and selectivity for TMBH are 70 and 55%, respectively.

Examples 30-31 in comparison with example 21 shows that a decrease in temperature leads to an increase in reaction time and a decrease in the conversion of TMP and selectivity for TMBH.

Example 32. The process is carried out as in example 30, but take 40 mg of the catalyst. After 0.5 h, the conversion of TMP and selectivity for TMBH are 98 and 86%, respectively.

Example 33. The process is carried out as in example 32, but after 6 minutes after the start of the reaction, the catalyst is filtered off and the transformation of TMP in the filtrate is monitored by GLC.

This example shows that leaching of the active component γ-PV ₂ W ₁₀ during the reaction does not occur and the oxidation of TMP is a heterogeneous process and proceeds on the surface of the catalyst, and not in the volume of the solution.

Example 34. The process is carried out as in example 16, but take the γ-PV ₂ W ₁₀ / CNF catalyst prepared as in example 11. After 0.25 hours, the conversion of TMP and selectivity for TMBH are 98 and 90%, respectively.

Example 35. The process is carried out as in example 16, but take the γ-PV ₂ W ₁₀ / CNF catalyst prepared as in example 12. After 0.25 hours, the conversion of TMP and selectivity for TMBH are 98 and 84%, respectively.

Example 36. The process is carried out as in example 16, but take the γ-PV ₂ W ₁₀ / CNF catalyst prepared as in example 13. After 0.25 hours, the conversion of TMP and selectivity for TMBH are 98 and 75%, respectively.

Examples 36-38 show that an increase in the nitrogen content in the CNF leads to a decrease in selectivity for TMBH.

Example 37. The process is carried out as in example 21, but instead of TMF take 0.1 mmol of 2,6-dimethylphenol (DMF). After 0.25 hours, DMF conversion and selectivity for 2,6-dimethylbenzoquinone are 90 and 90%, respectively.

Example 38. The process is carried out as in example 21, but 0.1 mmol of 2,6-di-tert-butylphenol is taken. After 0.25 hours, the conversion of 2,6-di-tert-butylphenol and the selectivity for 2,6-di-tert-butylbenzoquinone are 94 and 90%, respectively.

Examples 37-38 show that the oxidation of 2,6-dialkylphenols to 2,6-dialkyl-1,4-benzoquinones proceeds with high selectivity.

The above examples show that the method of producing quinones proposed by the present invention is quite cheap, easy to implement, environmentally friendly and allows to obtain the target product in high yield, without impurities of chlorine-containing compounds and transition metals.

a) Samples of the catalyst were not dried in vacuum before use.

b) Hot filtering (Fig.)

Reaction conditions: 60 mg of γ-PV ₂ W ₁₀ / N-CNT catalyst (15 wt.% Γ-PV ₂ W ₁₀ , 1.8 at.% N), substrate concentration 0.1, [H ₂ O ₂ ] / [substrate] = 1 / 3.5, reaction time 0.25 h, 60 ° C, MeCN.

Claims (13)

1. The catalyst for the process of producing substituted quinones by the oxidation of aromatic compounds with hydrogen peroxide, including vanadium-containing polyoxotungstate TBA _5-n H _n [γ-PV ₂ W ₁₀ O ₄₀ ], where n = 1, characterized in that the catalyst is a vanadium-containing polyoxotungstate TBA _5-n H _n [γ-PV ₂ W ₁₀ O ₄₀ ], where n = 1, mounted on a solid support - nitrogen-containing carbon material, which is a nanotube or nanofibre, the content of polyoxotungstate in the catalyst is 5-25 wt. % 2. The catalyst according to claim 1, characterized in that the nitrogen content in the carrier is 1-5 at. % 3. A method of preparing a heterogeneous catalyst, including vanadium-containing polyoxytungstate TBA _5-n H _n [γ-PV ₂ W ₁₀ O ₄₀ ], where n = 1, for the process of obtaining substituted quinones by oxidation of aromatic compounds with hydrogen peroxide, characterized in that the solution In the case of polyoxotungstate in acetonitrile, a carrier is added - a nitrogen-containing carbon material, which is nanotubes or nanofibers, and the mineral acid, the resulting catalyst is separated by filtration from the solution and dried, resulting in catalysis an ator, which is a vanadium-containing polyoxytungstate TBA _5-n H _n [γ-PV ₂ W ₁₀ O ₄₀ ], where n = 1, in an amount of 5-25 wt. %, mounted on a solid carrier - nitrogen-containing carbon material, which is a nanotube or nanofiber. 4. The method according to p. 3, characterized in that before the application process, the nitrogen-containing carbon material is dried in vacuum at a temperature not exceeding 100 ° C. 5. A method of producing substituted quinones by oxidation of aromatic compounds with hydrogen peroxide in the presence of a catalyst, including vanadium-containing polyoxungstate TBA _5-n H _n [γ-PV ₂ W ₁₀ O ₄₀ ], where n = 1, in an aromatic solvent - acetonitrile, characterized in that as a catalyst use the catalyst according to paragraphs. 1, 2 or prepared by the method according to paragraphs. 3, 4. 6. The method according to p. 5, characterized in that as aromatic compounds take substituted phenols, such as 2,3,6-trimethylphenol, 2,6-dimethylphenol and 2,6-ditretbutylphenol. 7. The method according to p. 5, characterized in that the catalyst before use is dried in vacuum at a temperature of not more than 60 ° C. 8. The method according to p. 5, characterized in that as the oxidizing agent use an aqueous solution of hydrogen peroxide with a hydrogen peroxide content of at least 30 wt. % 9. The method according to p. 5, characterized in that the process is conducted at a temperature not lower than 25 ° C. 10. The method according to p. 5, characterized in that use the concentration of the substrate is not higher than 0.15 M. 11. The method according to p. 5, characterized in that the use of the molar ratio of hydrogen peroxide / substrate is not lower than 2.3 / 1. 12. The method according to p. 5, characterized in that the molar ratio of substrate / active component of the catalyst is not lower than 66. 13. The method according to p. 5, characterized in that the catalyst is separated by filtration and reused.

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