A preparation method of vanadyl acetylacetonate

Abstract

The present invention provides a method for preparing vanadyl acetylacetonate, comprising the following steps: Step 1: Mix a vanadium source, a reducing agent and water to prepare a tetravalent vanadium solution; Step 2: Mix acetylacetone and a two-way solvent; Step 3: Pour the mixed solution in Step 2 into the tetravalent vanadium solution in Step 1, with the molar ratio of V to acetylacetone being 1:1.0 - 1.5, and carry out the reaction in a water bath at 70 - 100 °C until there are no bubbles, and the reaction ends; Step 4: After filtration, wash the filter residue with pure water and dry it to prepare vanadyl acetylacetonate. The method for preparing vanadyl acetylacetonate of the present invention has the advantages of short reaction time, high conversion rate and no waste generation.

Description

Technical Field

[0001] The present invention relates to the preparation technology of organometallic compounds, and particularly to a preparation method of vanadyl acetylacetonate. Background Art

[0002] Vanadyl acetylacetonate [VO(acac)2], as a common organometallic compound, is widely used as an oxidation catalyst, a catalyst precursor, medicine, a paint dryer, a pigment, etc. As an oxidation catalyst, vanadyl acetylacetonate can combine with oxidants such as tert-butyl hydroperoxide and be rapidly oxidized into a homogeneous pentavalent vanadium compound, thereby effectively oxidizing various organic functional groups, such as the oxidation of amines into nitro groups, the oxidation of sulfides into sulfoxides, and the epoxidation of olefins. In the field of pharmacology, vanadyl acetylacetonate can act as an insulin-like hypoglycemic drug and has advantages such as good fat solubility and low toxicity to the gastrointestinal tract compared with simple salt compounds such as VOSO4 and NaVO3. In terms of catalyst precursors, vanadyl acetylacetonate is often used as the initial reactant for synthesizing vanadium-oxygen complexes. By replacing the acetylacetonate group of VO(acac)2 with bidentate or tridentate ligands, optically active vanadium complexes can be obtained, which can be widely used in the field of asymmetric catalysis. In addition, by utilizing the characteristic that vanadyl acetylacetonate is easily decomposed by heating, nano-scale vanadium oxide catalysts with high catalytic activity can be obtained by heating and decomposing vanadyl acetylacetonate. For example, the currently commercialized SCR denitration catalyst is a nano-composite powder composed of vanadium pentoxide, tungsten trioxide, and titanium dioxide. With the increasingly strict formulation of environmental protection standards, the demand for vanadyl acetylacetonate in this regard is also increasing.

[0003] 1. The traditional method for synthesizing vanadyl acetylacetonate is to use ethanol as a reducing agent under the action of concentrated sulfuric acid to convert vanadium pentoxide into vanadyl sulfate, and then add acetylacetone and sodium carbonate to obtain vanadyl acetylacetonate. A large amount of concentrated sulfuric acid is required in the process. Therefore, the requirements for equipment are relatively high, and a large amount of pollution is generated.

[0004] 2. Directly reacting acetylacetone with vanadium pentoxide to prepare vanadyl acetylacetonate is a one-step reaction with a simple process, but the reaction requires long-term reflux.

[0005] 3. Using hydrogen peroxide as a reducing agent, first reducing vanadium pentoxide to vanadium dioxide, and then reacting it with acetylacetone to obtain vanadyl acetylacetonate. Since vanadium pentoxide can catalyze the violent decomposition of hydrogen peroxide, the reaction must be carried out in an ice bath at the beginning to prevent the reaction system from being too violent, resulting in bumping and overflowing of the material. After the reaction for a period of time, the reaction system is then heated and reacted for a period of time.

[0006] In the prior art, the reaction requires long-term reflux, or a large amount of concentrated sulfuric acid is used, and the reaction process is complex and not easy to control. Summary of the Invention

[0007] The object of the present invention is to propose a preparation method of vanadyl acetylacetonate, aiming at the problems that the traditional preparation method of vanadyl acetylacetonate requires long-time reflux or a large amount of concentrated sulfuric acid, and the reaction process is complex and not easy to control. This method has the advantages of short reaction time, high conversion rate and no waste generation.

[0008] To achieve the above object, the technical solution adopted by the present invention is: a preparation method of vanadyl acetylacetonate, comprising the following steps:

[0009] Step 1: Mix a vanadium source, a reducing agent and water to prepare a tetravalent vanadium solution;

[0010] Step 2: Mix acetylacetone and a two-way solvent;

[0011] Step 3: Pour the mixed solution in Step 2 into the tetravalent vanadium solution in Step 1, with the molar ratio of V to acetylacetone being 1:1.0 - 1.5, and react in a water bath at 70 - 100 °C until no bubbles are generated, then the reaction ends;

[0012] Step 4: Filter and wash the filter residue with pure water, and dry it to prepare vanadyl acetylacetonate.

[0013] Further, the vanadium source is:

[0014] Vanadium pentoxide;

[0015] Or, a mixture of vanadium pentoxide and vanadium tetraoxide;

[0016] Or, a mixture of vanadium pentoxide and vanadium trioxide.

[0017] Further, the vanadium source is preferably vanadium pentoxide.

[0018] Further, the reducing agent is an organic or inorganic acid with reducibility.

[0019] Further, the reducing agent is one or more of oxalic acid, citric acid, tartaric acid, salicylic acid and ascorbic acid.

[0020] Further, the reducing agent is preferably oxalic acid.

[0021] Further, the dosage of the reducing agent in Step 1 is: greater than or equal to the dosage that can oxidize the vanadium source into tetravalent vanadium. Preferably, the dosage of the reducing agent is: 1 - 1.3 times the dosage that can oxidize the vanadium source into tetravalent vanadium.

[0022] Further, in Step 1, the molar ratio of V2O5:H2C2O4:H2O is 1:1.0 - 1.3:1 - 10, and the preferred molar ratio is 1:1.1 - 1.3:5 - 10.

[0023] Further, in Step 2, the mass ratio of acetylacetone to the two-way solvent is 1:0.2 - 1.0, preferably 1:0.5 - 1.0.

[0024] Further, the two-way solvent is a solvent that is soluble in both water and acetylacetone.

[0025] Further, the two-way solvent is one or more of ethanol, N-methylpyrrolidone, toluene, acetone, and methanol.

[0026] Further, the water bath temperature in Step 3 is 90 - 100 °C.

[0027] Further, the reaction time in Step 3 is 1 - 6 h.

[0028] Further, the filtrate obtained by filtration and the washing water in Step 4 are used as the circulating water in Step 1.

[0029] Further, the number of water washing times in Step 4 is 1 - 3 times.

[0030] Further, the drying conditions in Step 4 are drying at 50 - 200 °C, preferably 80 - 150 °C, for 4 - 10 h, preferably 4 - 8 h.

[0031] Taking vanadium source as vanadium pentoxide and reducing agent as oxalic acid as an example, the reaction equation of the present invention is as follows:

[0032] Step 1: 3H2C2O4 + V2O5 = 2VOC2O4 + 2CO2 + 3H2O

[0033] Step 3

[0034] VOC2O4 + H2(acac)2 = VO(acac)2 + H2C2O4

[0035] The preparation method of vanadyl acetylacetonate disclosed in the present invention has the following advantages compared with the prior art:

[0036] 1) The reaction steps of the present invention are simple. It uses a water bath reaction without high temperature and high pressure, and the operation is safe.

[0037] 2) The filtrate of the present invention can be recycled and no waste is generated.

[0038] 3) The present invention does not introduce other impurities. The generated VOC2O4 and the solvent can be washed clean, and the product purity is high.

[0039] 4) The conversion rate of the target product of the present invention is high. Because as long as there is a reducing agent reaction, VOC2O4 will be generated, and then acetylacetone will be generated, while the reducing agent is also generated. This process repeats, and the conversion rate is greater than 98%. Moreover, the whole reduction reaction is rapid and the reaction time is short. Description of the Drawings

[0040] Figure 1 XRD pattern of vanadyl acetylacetonate for Example 1;

[0041] Figure 2 XRD pattern of vanadyl acetylacetonate for Example 2

[0042] Figure 3 It is a reaction flow chart. Detailed implementation manners

[0043] The present invention will be further described below in conjunction with embodiments:

[0044] Example 1

[0045] This example discloses a preparation method of vanadyl acetylacetonate, as Figure 3 shown, which specifically includes the following steps:

[0046] 1. Weigh V2O5, oxalic acid and water respectively according to the molar ratio of 1:1.0:5, place them in a container, and continuously stir in a water bath at 70 °C for 2 h until no bubbles are generated, and the reaction ends;

[0047] 2. According to V: acetylacetone (molar ratio) = 1:1, and the mass ratio of acetylacetone to N-methylpyrrolidone is 1:0.3, weigh the two substances and place them in a container, and fully mix them under stirring until a homogeneous liquid is formed;

[0048] 3. Add the solution in step 2 to step 1, raise the temperature of the water bath to 90 °C, and fully react for 3 h until no bubbles are present;

[0049] 4. Filter the mixture after the above reaction, and wash it twice with clear water;

[0050] 5. Dry the washed solid, the drying temperature is 100 °C, and the drying time is 5 h to obtain vanadyl acetylacetonate.

[0051] The X-ray diffraction pattern of the product obtained in this example is shown in Figure 1 . From Figure 1 it can be seen that a pure-phase vanadyl acetylacetonate material is synthesized by this method. There are no impurity peaks in the spectrum, indicating high product purity, and the diffraction peaks are narrow and sharp, indicating good crystallinity.

[0052] Example 2

[0053] This example discloses a preparation method of vanadyl acetylacetonate, as Figure 3 shown, which specifically includes the following steps:

[0054] 1. Weigh V2O5, oxalic acid and water respectively according to the molar ratio of 1:1.1:6, place them in a container, and continuously stir in a water bath at 80 °C for 3 h until no bubbles are generated, and the reaction ends;

[0055] 2. According to the V: acetylacetone (molar ratio) = 1:1, and the mass ratio of acetylacetone to N-methylpyrrolidone is 1:0.4, weigh the two substances and place them in a container, stir and mix them thoroughly until a uniform liquid is formed;

[0056] 3. Add the solution in step 2 to step 1, raise the water bath temperature to 95°C, and allow to react for 4 hours until there are no bubbles;

[0057] 4. Filter the reaction mixture and wash twice with clean water;

[0058] 5. Dry the washed solid at 110°C for 4 hours to obtain vanadium acetylacetonate.

[0059] The X-ray diffraction pattern of the product obtained in this example is shown in Figure 2 .Depend on Figure 1 It can be seen that pure phase acetylacetonato vanadium material was synthesized by this method. There is no impurity peak in the spectrum, indicating that the product is of high purity, and the diffraction peak is narrow and sharp, indicating good crystallinity.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A preparation method of vanadyl acetylacetonate, characterized in that, It includes the following steps: In step 1, a vanadium source, a reducing agent and water are mixed to prepare a tetravalent vanadium solution; the reducing agent is oxalic acid and the vanadium source is vanadium pentoxide; In step 2, acetylacetone and a two-way solvent are mixed; the two-way solvent is N-methylpyrrolidone; The mass ratio of acetylacetone to the two-way solvent is: 1:0.2 - 1.0; In step 3, the mixed solution in step 2 is poured into the tetravalent vanadium solution in step 1, and the molar ratio of V to acetylacetone is 1:1.0 - 1.

5. The reaction is carried out in a water bath at 90 - 100 °C until there are no more bubbles, and the reaction ends; In step 4, after filtration, the filter residue is washed with pure water and dried to prepare vanadyl acetylacetonate.

2. The preparation method of vanadyl acetylacetonate according to claim 1, wherein The dosage of the reducing agent is greater than or equal to the dosage capable of reducing the vanadium source to tetravalent vanadium.

3. The preparation method of vanadyl acetylacetonate according to claim 1, wherein The filtrate obtained by filtration in step 4 and the washing water are recycled as the water in step 1.

4. The preparation method of vanadyl acetylacetonate according to claim 1, wherein, The drying condition in step 4 is to use 50 - 200 °C and dry for 4 - 10 h.

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