Preparation method of ruthenium acetylacetonate

Abstract

The invention belongs to the technical field of ruthenium catalysts, and discloses a preparation method of ruthenium acetylacetonate. According to the method, ruthenium nitrate and acetylacetone are used as raw materials, triethylamine is used as an alkaline agent, water is used as a solvent, and ruthenium acetylacetonate is synthesized through a heating reaction. According to the preparation method, water-soluble ruthenium nitrate and acetylacetone are adopted as initial raw materials, water is adopted as a reaction solvent, triethylamine is adopted as an alkaline condition, the reaction is completed through a one-pot method under the mild reaction condition, the purification process is simple, the yield is high, chloride ions are not introduced, the requirement for equipment is low, the dosage of reactants can reach the hectogram level, and the preparation method is suitable for batch production.

Description

Technical Field

[0001] This invention relates to the field of ruthenium catalyst preparation technology, specifically a method for preparing ruthenium acetylacetone. Background Technology

[0002] Platinum group metal ruthenium acetylacetonate complexes exhibit electrophilicity, nucleophilicity, and special redox selectivity in chemical reactions, making them ideal homogeneous and highly efficient catalysts for organic synthesis reactions.

[0003] Among these properties, the electrophilic nature of ruthenium acetylacetonate compounds enables them to efficiently catalyze reactions such as the activation of CH bonds. These reactions are typically difficult to achieve, but with the participation of ruthenium acetylacetonate compounds, the reaction conditions are significantly improved, enabling the synthesis of a range of complex organic molecules. In particular, ruthenium acetylacetonate compounds have demonstrated excellent catalytic performance for reactions such as cyclization of alkenes, addition reactions of alkynes, and CH bond functionalization of aromatic compounds.

[0004] Furthermore, the nucleophilicity of ruthenium acetylacetone compounds exhibits unique advantages in certain reactions. For example, in transesterification and alkylation reactions, ruthenium acetylacetone compounds can efficiently promote the activation of the reaction substrate, thereby increasing the reaction rate and yield. This catalytic property not only simplifies the reaction process but also reduces energy consumption, which is of great significance for the development of sustainable chemistry.

[0005] More importantly, the selectivity exhibited by ruthenium acetylacetonate compounds in redox reactions makes them irreplaceable in complex organic synthesis involving multi-step redox processes. For example, in certain oxidation reactions, ruthenium acetylacetonate compounds can selectively oxidize specific functional groups without affecting the structure of other sensitive groups. This selectivity not only improves the purity of the target product but also reduces the formation of byproducts, thereby increasing the overall reaction efficiency.

[0006] Although ruthenium acetylacetonate has a wide range of applications, its synthesis has always been a major challenge limiting its use. Traditional methods use hydrated ruthenium trichloride and acetylacetonate as raw materials, reacting under reflux in ethanol and water as solvents. The reaction is carried out under alkaline conditions for more than 24 hours to obtain ruthenium acetylacetonate, with a yield of 60%–90%. Multiple recrystallizations are required for purification, and Cl... - Residues increase the hygroscopicity of the product. This method has a long reaction time and unstable yield, and is only applicable to milligram-scale reactions, making it impossible to achieve large-scale production. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a method for preparing ruthenium acetylacetonate, which features mild reaction conditions, simple operation, environmentally friendly solvents, high yield, and no residual Cl.- These advantages solve the problems of low yield, need for multiple recrystallization purification, and Cl... - The residue leads to increased hygroscopicity of the product.

[0008] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing ruthenium acetylacetone, comprising the following steps: Acetylacetone and triethylamine were mixed and heated to obtain a mixed reaction solution. Ruthenium nitrate was then dissolved in water to obtain an aqueous solution of ruthenium nitrate. The aqueous solution of ruthenium nitrate was added dropwise to the mixed reaction solution. After the addition was complete, the reaction was continued to be heated for a period of time, and then the solid and liquid were separated. The solid was washed and dried to obtain ruthenium acetylacetone.

[0009] Preferably, the molar ratio of ruthenium nitrate to acetylacetone is 1:(3~8).

[0010] Preferably, the molar ratio of ruthenium nitrate to triethylamine is 1:(9~15).

[0011] Preferably, the conditions for heating the mixture of acetylacetone and triethylamine are: stirring and heating to 60~90℃, and continuing to stir for 0.5~1h.

[0012] Preferably, the water is distilled water.

[0013] Preferably, the mass ratio of ruthenium nitrate to water is 1:(8~13), with units of g:mL.

[0014] Preferably, the dropping rate of the ruthenium nitrate aqueous solution is 10~15 mL / min.

[0015] Preferably, the conditions for continuing the reaction after adding the ruthenium nitrate aqueous solution are: temperature of 85~110℃ and reaction time of 3~5h.

[0016] Preferably, the washing reagent is water, and the washing is performed 1 to 2 times.

[0017] Preferably, the drying temperature is 60~80℃ and the time is 4~6h.

[0018] Compared with the prior art, the present invention provides a method for preparing ruthenium acetylacetone, which has the following beneficial effects: This invention provides a method for preparing ruthenium acetylacetone, comprising the following steps: acetylacetone and triethylamine are added to a reaction flask and heated to react; then ruthenium nitrate is dissolved in water and slowly added dropwise to the mixed reaction solution; after the addition is complete, the reaction is continued to be heated for a period of time to obtain ruthenium acetylacetone. The preparation method of this invention uses ruthenium nitrate and acetylacetone as reactants, water as a solvent, and triethylamine as an alkaline condition. The reaction is completed in a one-pot process, with mild reaction conditions, low equipment requirements, and simple operation. Furthermore, this invention uses water as a solvent because, firstly, the ruthenium nitrate raw material has the advantage of strong solubility in water-based solvents, and the other raw material is a solution, while the reaction product ruthenium acetylacetone is insoluble in water, simplifying purification and improving product quality; secondly, water-based solvents are safe, environmentally friendly, and inexpensive, thereby reducing environmental pollution and lowering costs. Furthermore, this invention employs a one-pot reaction, which involves fewer steps, is easy to operate, requires less sophisticated equipment, and allows for reactant quantities down to the hundred-gram level, enabling mass production. Example results show that the preparation method provided by this invention can achieve the successful synthesis of ruthenium acetylacetone in just 5-7 hours, with a short reaction time and no residual Cl. - Furthermore, the yield of ruthenium nitrate obtained is ≥95.5%, which is a significant improvement compared to existing technologies. Attached Figure Description

[0019] Figure 1 The infrared spectrum of ruthenium acetylacetone prepared in Example 1 of this invention.

[0020] Figure 2 The crystal molecular structure of ruthenium acetylacetonate prepared in Example 1 of this invention is shown. Detailed Implementation

[0021] In this invention, the ruthenium mass percentage in the ruthenium nitrate is preferably 31.85% to 31.89%. In specific embodiments of this invention, the ruthenium mass fraction in the ruthenium nitrate can be 31.86%, 31.87%, or 31.88%, etc. The ruthenium nitrate used in this invention has good solubility, which is beneficial to the reaction.

[0022] In this invention, the molar ratio of ruthenium nitrate to acetylacetone is 1:3 to 8, specifically 1:4, 1:5, or 1:7, etc.

[0023] In this invention, the molar ratio of ruthenium nitrate to triethylamine is 1:10 to 15, specifically 1:10, 1:12, or 1:14, etc.

[0024] In this invention, heating the mixture of acetylacetone and triethylamine includes: After mixing acetylacetone and triethylamine, stir and heat to 60~90℃, specifically 65℃, 75℃ or 85℃, etc.; stir for 0.5~1h, specifically 0.5h, 0.7h or 0.9h, etc., to obtain a mixed solution.

[0025] In this invention, water is preferably distilled water; the mass ratio of ruthenium nitrate to water is 1g:8mL~13mL, specifically 1g:9mL, 1g:10mL, or 1g:12mL, etc.; the slow dripping rate of the ruthenium nitrate solution is 10~15mL / min, specifically 10mL / min, 12mL / min, or 14mL / min, etc.; the heating reaction temperature is 85~110℃, specifically 90℃, 95℃, or 100℃, etc.; the reaction time is 3~5h, specifically 3h, 4h, or 5h, etc. This invention uses water as a solvent, which can greatly reduce production costs and achieve green environmental protection.

[0026] In this invention, after the substitution coordination reaction, the resulting reaction system is further subjected to filtration, washing, and drying in sequence. The washing reagent is water; the number of washings is 1 to 2; the drying temperature is 60 to 80°C, and the time is 4 to 6 hours; the washing reagent is preferably water, more preferably distilled water; the number of washings is preferably 1 to 2; the drying temperature is preferably 60 to 80°C, specifically 60°C, 70°C, or 80°C, etc.; the drying time is preferably 4 to 6 hours, specifically 4 hours, 5 hours, or 6 hours, etc. This invention removes unreacted ruthenium nitrate through washing.

[0027] This invention uses ruthenium nitrate and acetylacetone as raw materials, water as solvent, and triethylamine as alkaline condition. The reaction is carried out in a one-pot process with mild reaction conditions, few steps, simple operation, low environmental pollution, low cost, high product yield, low equipment requirements, and reactant dosage can reach the hundred-gram level, enabling mass production.

[0028] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0029] In the following examples, ruthenium nitrate, acetylacetone, and triethylamine are all commercially available analytical grade products.

[0030] Example 1 252 g (2.52 mol) of acetylacetone and 637.5 g (6.40 mol) of triethylamine were added to a reaction flask, mixed, heated to 65 °C, and stirred for 0.5 h to obtain a mixed solution. Then, 200 g (0.697 mol) of ruthenium nitrate (ruthenium mass content of 31.86%) was dissolved in 1800 mL of distilled water to obtain an aqueous solution of ruthenium nitrate. The aqueous solution of ruthenium nitrate was added dropwise to the mixed solution at a rate of 10 mL / min. After the addition was complete, the mixture was heated to 90 °C and stirred for 3 h. After naturally cooling to room temperature, the mixture was filtered, and the filter cake was washed once with distilled water and dried at 60 °C for 4 h to obtain 243.5 g of red solid, with a yield of 96.9% based on ruthenium.

[0031] Example 2 315.4 g of acetylacetone (3.154 mol) and 765.0 g (7.553 mol) of triethylamine were added to a reaction flask, mixed, heated to 75 °C, and stirred for 0.7 h to obtain a mixed solution. Then, 200 g (0.697 mol) of ruthenium nitrate (ruthenium content 31.87%) was dissolved in 2000 mL of distilled water to obtain an aqueous solution of ruthenium nitrate. The aqueous solution of ruthenium nitrate was added dropwise to the mixed solution at a rate of 12 mL / min. After the addition was complete, the mixture was heated to 95 °C and stirred for 4 h. After naturally cooling to room temperature, the mixture was filtered, and the filter cake was washed twice with distilled water and dried at 70 °C for 5 h to obtain 244.1 g of red solid, with a yield of 97.2% based on ruthenium.

[0032] Example 3 441.5 g (4.410 mol) of acetylacetone and 892.5 g (8.821 mol) of triethylamine were added to a reaction flask, mixed, heated to 85 °C, and stirred for 0.9 h to obtain a mixed solution. Then, 200 g (0.697 mol) of ruthenium nitrate (ruthenium content 31.88%) was dissolved in 2400 mL of distilled water to obtain an aqueous solution of ruthenium nitrate. The aqueous solution of ruthenium nitrate was added dropwise to the mixed solution at a rate of 14 mL / min. After the addition was complete, the mixture was heated to 100 °C and stirred for 5 h. After naturally cooling to room temperature, the mixture was filtered, and the filter cake was washed twice with distilled water and dried at 80 °C for 6 h to obtain 243.6 g of red solid, with a yield of 96.9% based on ruthenium.

[0033] Elemental analysis and characterization were performed on the ruthenium acetylacetone obtained in Example 1. The resulting proton NMR spectrum, carbon NMR spectrum, and crystal structure spectrum are shown below. Figures 1-2 .

[0034] Elemental analysis: Theoretical values ​​(%): C 45.22, H 5.31; Measured values ​​(%): C 45.21, H 5.30. The measured values ​​are in good agreement with the theoretical values.

[0035] Depend on Figure 1As can be seen, the infrared spectrum IR (cm) -1 , KBr): 3074, 2999, 2966, 2921, 2838, 1550, 1511, 1424, 1376, 1268, 1020, 935, 683.

[0036] Depend on Figure 2 As can be seen from the figure, the measured molecular structure is in complete agreement with the theory.

[0037] Elemental analysis, 1H NMR, 1C NMR, and crystal structure analysis showed that the product obtained in Example 1 was consistent with the target compound ruthenium acetylacetone. Elemental analysis, 1H NMR, and 1C NMR of the products obtained in Examples 2 and 3 also showed that the products were consistent with the target compound ruthenium acetylacetone.

[0038] Comparative Example 1 As a comparison, this comparative example differs from Example 1 in that sodium hydroxide is used instead of triethylamine as the alkaline condition; otherwise, it is the same as Example 1. 252g of acetylacetone and 637.5g of sodium hydroxide were added to a reaction flask, mixed and heated to 65℃, and stirred for 0.5h to obtain a mixed solution. Then, 200g of ruthenium nitrate (ruthenium mass content of 31.86%) was dissolved in 1800mL of distilled water to obtain an aqueous solution of ruthenium nitrate. The aqueous solution of ruthenium nitrate was added dropwise to the mixed solution at a rate of 10mL / min. After the addition was completed, the mixture was heated to 90℃ and stirred for 3h. After naturally cooling to room temperature, the mixture was filtered, and the filter cake was washed once with distilled water and dried at 60℃ for 4h to obtain 150g of red solid, with a yield of 59.7% based on ruthenium.

[0039] Comparative Example 2 As a comparison, this comparative example differs from Example 1 in that potassium carbonate is used instead of triethylamine as the alkaline condition; otherwise, it is the same as Example 1.

[0040] 252g of acetylacetone and 637.5g of potassium carbonate were added to a reaction flask, mixed and heated to 65℃, and stirred for 0.5h to obtain a mixed solution. Then, 200g of ruthenium nitrate (ruthenium mass content of 31.86%) was dissolved in 1800mL of distilled water to obtain an aqueous solution of ruthenium nitrate. The aqueous solution of ruthenium nitrate was added dropwise to the mixed solution at a rate of 10mL / min. After the addition was completed, the mixture was heated to 90℃ and stirred for 3h. After naturally cooling to room temperature, the mixture was filtered, and the filter cake was washed once with distilled water and dried at 60℃ for 4h to obtain 140g of red solid, with a yield of 55.7% based on ruthenium.

[0041] The reasons for the low yields of products in Comparative Example 1 and Comparative Example 2 are as follows: First, strong alkalinity triggers ligand side reactions. Excessive alkalinity causes the ligand (acetylacetone) to become ineffective. As a β-diketone ligand, acetylacetone will only moderately dissociate into an active enol form in triethylamine (a weak base) to efficiently coordinate with ruthenium ions. However, potassium carbonate or sodium hydroxide are strong inorganic bases that will excessively catalyze the hydrolysis (decomposition into acetate and acetone) or self-condensation (generating polymers without coordination activity) of acetylacetone, resulting in a significant reduction in the amount of effective ligands participating in ruthenium ion coordination and a direct decrease in the amount of the target complex formed.

[0042] Second, the system has poor homogeneity, and the incomplete reaction of ruthenium ions leads to the formation of impurities. Triethylamine is an organic base with good compatibility with the organic ligand acetylacetone, which can form a uniform organic reaction environment, ensuring that ruthenium ions can uniformly contact the ligand and fully coordinate after being added. However, potassium carbonate is an inorganic salt and NaOH is an inorganic base, which has poor compatibility with acetylacetone (an organic compound), and is prone to forming local uneven concentration regions in the system. In some regions, the alkalinity is too strong, causing ruthenium ions to prematurely generate amorphous impurities such as ruthenium hydroxide (non-target products). In other regions, the ligands are insufficient, causing ruthenium ions to not participate in the reaction and eventually be lost with the mother liquor or during the washing process.

[0043] Third, strong alkalinity disrupts the stability of the target complex. The target complex formed by ruthenium and acetylacetone (such as ruthenium acetylacetone) is stable in a weakly alkaline / neutral environment, but the strong alkalinity provided by potassium carbonate breaks the coordination bonds in the complex, causing the formed complex to dissociate into free ruthenium ions. These free ruthenium ions cannot form a solid product and will be lost during filtration or washing steps, further reducing the yield of the target product.

[0044] Comparative Example 3 As a comparison, this comparative example differs from Example 1 in that ruthenium acetate is used instead of ruthenium nitrate; otherwise, they are the same as in Example 1.

[0045] 252g of acetylacetone and 637.5g of triethylamine were added to a reaction flask, mixed and heated to 65℃, and stirred for 0.5h to obtain a mixed solution. Then, 200g of ruthenium acetate (ruthenium mass content of 31.86%) was dissolved in 1800mL of distilled water to obtain an aqueous solution of ruthenium acetate. The aqueous solution of ruthenium acetate was added dropwise to the mixed solution at a rate of 10mL / min. After the addition was completed, the mixture was heated to 90℃ and stirred for 3h. After naturally cooling to room temperature, ruthenium acetate was found to be insoluble in water. The mixture was filtered to obtain a black solid, but the target product was not obtained.

Claims

1. A method for preparing ruthenium acetylacetone, characterized in that: Includes the following steps: Acetylacetone and triethylamine were mixed and heated to obtain a mixed reaction solution. Ruthenium nitrate was then dissolved in water to obtain an aqueous solution of ruthenium nitrate. The aqueous solution of ruthenium nitrate was added dropwise to the mixed reaction solution. After the addition of the aqueous solution of ruthenium nitrate was completed, the reaction was continued to be heated and the solid and liquid were separated. The solid was washed and dried to obtain ruthenium acetylacetone.

2. The method for preparing ruthenium acetylacetone according to claim 1, characterized in that: The molar ratio of ruthenium nitrate to acetylacetone is 1:(3~8).

3. The method for preparing ruthenium acetylacetone according to claim 1, characterized in that: The molar ratio of ruthenium nitrate to triethylamine is 1:(9~15).

4. The method for preparing ruthenium acetylacetone according to claim 1, characterized in that: The conditions for heating the mixture of acetylacetone and triethylamine are as follows: heat to 60-90°C with stirring, and continue stirring for 0.5-1 hour.

5. The method for preparing ruthenium acetylacetone according to claim 1, characterized in that: The water is distilled water.

6. The method for preparing ruthenium acetylacetone according to claim 1, characterized in that: The mass ratio of ruthenium nitrate to water is 1:(8~13), and the unit is g:mL.

7. The method for preparing ruthenium acetylacetone according to claim 1, characterized in that: The dropping rate of the ruthenium nitrate aqueous solution is 10~15 mL / min.

8. The method for preparing ruthenium acetylacetone according to claim 1, characterized in that: The conditions for continuing the reaction after adding the ruthenium nitrate aqueous solution are: temperature 85~110℃, reaction time 3~5h.

9. The method for preparing ruthenium acetylacetone according to claim 1, characterized in that: The washing reagent is water, and the washing is performed 1 to 2 times.

10. The method for preparing ruthenium acetylacetone according to claim 1, characterized in that: The drying temperature is 60~80℃, and the time is 4~6 hours.

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