A method for preparing 1-(4-chlorophenyl)-3-pyrazolol

Abstract

A method for preparing 1-(4-chlorophenyl)-3-pyrazolol, which is characterized in that an ionic liquid is used as a solvent and a catalyst to dissolve and catalyze the air oxidation reaction of 1-(4-chlorophenyl)pyrazolidin-3-one to prepare 1-(4-chlorophenyl)-3-pyrazolol. The mass ratio of 1-(4-chlorophenyl)pyrazolidin-3-one to the ionic liquid is 1:20 to 1:10, the air flow rate is 20 to 40 L / min, the reaction temperature is 50 to 80 °C, and the reaction time is 5 to 8 h. After the reaction, an extractant is used to extract the product 1-(4-chlorophenyl)-3-pyrazolol. After combining the extraction liquid and recovering the extractant by vacuum distillation, the product 1-(4-chlorophenyl)-3-pyrazolol is obtained. Its yield is 98.0% to 99.2%, and the purity is 98.9% to 99.6%. The raffinate is the ionic liquid. The characteristics of the present invention are: the reaction conditions are mild, the operation is simple, and the product yield is high; the ionic liquid has the dual functions of a solvent and a catalyst, and the synergistic effect of the two improves the reaction efficiency; the appropriate L acidity strength of the ionic liquid avoids side reactions such as over-oxidation and decomposition of the product; the ionic liquid is easy to separate from the product, the active center does not lose, and it can be reused.

Description

Technical Field

[0001] The present invention relates to the field of fine organic synthesis, and particularly to a method for preparing 1-(4-chlorophenyl)-3-pyrazolol by dissolving and catalyzing the air oxidation reaction of 1-(4-chlorophenyl)pyrazolidin-3-one by using an ionic liquid as a solvent and a catalyst. Background Art

[0002] Pyraclostrobin is a new type of methoxyacrylate fungicide, which has the characteristics of low toxicity and low residue, safety for non-target organisms, small dosage and environmental friendliness. 1-(4-Chlorophenyl)-3-pyrazolol is a key intermediate for preparing pyraclostrobin. At present, it is prepared by the hydrogen peroxide oxidation method, which has the problems of large consumption of hydrogen peroxide, high danger, large amount of wastewater generation, and the inorganic ions in the wastewater are mixed salts, so it is impossible to prepare by-products with high salt content, and it is difficult to recycle, which has become a bottleneck restricting the production of pyraclostrobin. It can be seen that the optimization of its preparation method is crucial for improving the efficiency of the entire production process and the product quality.

[0003] Air is a clean and inexpensive oxidant. By using catalytic air oxidation of 1-(4-chlorophenyl)pyrazolidin-3-one to prepare 1-(4-chlorophenyl)-3-pyrazolol, the safety hazards caused by using hydrogen peroxide as an oxidant can be avoided, the yield of 1-(4-chlorophenyl)-3-pyrazolol can be increased, the raw material cost can be reduced, the economic benefit can be improved, the amount of wastewater generation can be reduced, and clean production can be realized. At present, the catalytic air oxidation of 1-(4-chlorophenyl)pyrazolidin-3-one to prepare 1-(4-chlorophenyl)-3-pyrazolol is mostly carried out in an alkaline solution. The reason is that the raw material 1-(4-chlorophenyl)pyrazolidin-3-one is soluble in the alkaline solution, and the oxidation reaction of 1-(4-chlorophenyl)pyrazolidin-3-one can be realized in a homogeneous system. This technology has defects such as large consumption of alkali, the need to use acidic substances for neutralization after the reaction, and under acidic conditions, the product 1-(4-chlorophenyl)-3-pyrazolol is extremely prone to dehydration side reactions, resulting in low product yield, poor quality, and large discharge of saline wastewater.

[0004] As a solvent and catalyst, ionic liquids have outstanding properties such as good solubility, high catalytic activity and selectivity, designability, good stability, and easy recovery and recycling. These properties enable ionic liquids to play an increasingly important role in chemical industrial production and environmental protection. Therefore, this invention applies for a method for preparing 1-(4-chlorophenyl)-3-pyrazolol, which is characterized by using ionic liquid as a solvent and catalyst to dissolve and catalyze the air oxidation reaction of 1-(4-chlorophenyl)pyrazolidin-3-one to prepare 1-(4-chlorophenyl)-3-pyrazolol. During the oxidation reaction, the ionic liquid can directly dissolve the raw material 1-(4-chlorophenyl)pyrazolidin-3-one, providing a basis for the rapid oxidation of the raw material under a homogeneous system; at the same time, the negative ions in the ionic liquid contain the metal active sites required for the oxidation reaction, and these active sites are evenly distributed and in contact with the raw material, providing more reaction sites for the oxidation reaction. The synergistic effect of the two improves the reaction efficiency; the appropriate L acid strength of the ionic liquid avoids side reactions such as over-oxidation and decomposition of the product; in addition, the ionic liquid and the product are easily separated after the reaction and can be reused. This invention has made breakthroughs in the technological innovation of the green production process of 1-(4-chlorophenyl)-3-pyrazolol, especially in using more environmentally friendly and efficient catalysts, solvents, and optimizing reaction conditions, etc., and has important academic significance and potential application prospects. Summary of the Invention

[0005] The purpose of this invention is to replace the preparation method of 1-(4-chlorophenyl)-3-pyrazolol under the traditional hydrogen peroxide oxidant system, and develop a method for oxidizing and preparing 1-(4-chlorophenyl)-3-pyrazolol with air as the oxidant under mild reaction conditions, so as to solve the problems such as the consumption of a large amount of reducing agent to reduce the excessive hydrogen peroxide after the reaction, a large amount of wastewater discharge, and the non-reusability of the catalyst in the traditional hydrogen peroxide oxidant system.

[0006] A method for preparing 1-(4-chlorophenyl)-3-pyrazolol, which is characterized by using ionic liquid as a solvent and catalyst to dissolve and catalyze the air oxidation reaction of 1-(4-chlorophenyl)pyrazolidin-3-one to prepare 1-(4-chlorophenyl)-3-pyrazolol. The mass ratio of 1-(4-chlorophenyl)pyrazolidin-3-one to ionic liquid is 1:20 to 1:10, the air flow rate is 20 to 40 L / min, the reaction temperature is 50 to 80 °C, the reaction time is 5 to 8 h. After the reaction, the product 1-(4-chlorophenyl)-3-pyrazolol is extracted 3 times with an extractant having the same volume as the reaction mixture. After combining the extraction liquids and recovering the extractant by vacuum distillation, the product 1-(4-chlorophenyl)-3-pyrazolol is obtained. Its yield is 98.0% to 99.2%, and the purity is 98.9% to 99.6%. The raffinate is the ionic liquid and can be directly recycled; the ionic liquid is 1-ethyl-3-methylimidazolium chloride-ferric chloride [C 2 mimCl][FeCl3 , 1-butyl-3-methylimidazolium chloride-ferric chloride salt [C 4 mimCl][FeCl 3 , 1-ethyl-3-methylimidazolium chloride-manganese acetate salt [C 2 mim][MnClAc], 1-butyl-3-methylimidazolium chloride-manganese acetate salt [C 4 mim][MnClAc], 1-ethyl-3-methylimidazolium chloride-cobalt acetate salt [C 2 mim][CoClAc], 1-butyl-3-methylimidazolium chloride-cobalt acetate salt [C 4 mim][CoClAc]; and the extractant is one of toluene, methyl isobutyl ketone, or tetrahydrofuran.

[0007] The present invention solves this technical problem through the following technical solutions:

[0008] Taking 1-butyl-3-methylimidazolium chloride-cobalt acetate salt [C 4 mim][CoClAc] ionic liquid as an example to illustrate the specific technical solution.

[0009] Put 15 g of [C 4 mim][CoClAc] and 1 g of 1-(4-chlorophenyl)pyrazolidin-3-one into a reaction kettle equipped with magnetic stirring, a thermometer, and a gas distributor. When the materials in the kettle are heated to 70 °C, start passing air at a flow rate of 30 L / min, and keep stirring and reacting for 6 h. After the reaction is completed, quickly cool the reaction kettle to room temperature in a water bath. Use toluene, an extractant with the same volume as the reaction mixture, to extract the product 1-(4-chlorophenyl)-3-pyrazolol 3 times. Combine the extractive solutions and recover the extractant by vacuum distillation. Then, the product 1-(4-chlorophenyl)-3-pyrazolol is obtained. Its yield is 99.2%, and the purity is 99.6%. The raffinate is an ionic liquid and can be directly recycled.

[0010] Compared with the traditional method, the present invention has the following characteristics:

[0011] 1. The reaction conditions are mild, the operation is simple, and the product yield and purity are high.

[0012] 2. The ionic liquid has the dual functions of a solvent and a catalyst, and the synergistic effect of the two improves the reaction efficiency.

[0013] 3. The appropriate L acid strength of the ionic liquid avoids side reactions such as over-oxidation and decomposition of the product.

[0014] 4. The ionic liquid is easy to separate from the product, the active center does not leak, and it can be reused. Specific implementation method

[0015] The method of the present invention will be further described below in conjunction with embodiments, which is not a limitation to the present invention.

[0016] Example 1: 10 g of 1-butyl-3-methylimidazolium chloroacetate cobalt salt [C 4 mim][CoClAc] ionic liquid and 1 g of 1-(4-chlorophenyl)pyrazolidin-3-one were put into a reaction kettle equipped with magnetic stirring, a thermometer and a gas distributor. When the materials in the kettle were heated to 70 °C, air was introduced at a flow rate of 20 L / min, and the mixture was stirred and reacted at a constant temperature for 6 h. After the reaction was completed, the reaction kettle was quickly cooled to room temperature in a water bath. The product 1-(4-chlorophenyl)-3-pyrazolol was extracted 3 times with toluene as the extractant having the same volume as the reaction mixture. After the extractive solutions were combined and the extractant was recovered by distillation under reduced pressure, the product 1-(4-chlorophenyl)-3-pyrazolol was obtained. Its yield was 99.0%, purity was 99.3%, and the raffinate was the ionic liquid, which could be directly recycled.

[0017] Comparative Example 1: This comparative example provides a method for preparing 1-(4-chlorophenyl)-3-pyrazolol. The difference from the example is that in the comparative example, an ionic liquid is not used as a solvent and a catalyst, but formic acid is used as a solvent and ferric chloride is used as a catalyst. The specific dosages are as follows: 90 g of formic acid was added to the reaction kettle, and 20 g of 1-(4-chlorophenyl)pyrazolidin-3-one and 1.6 g of ferric chloride were added with stirring. The temperature was raised to 90 °C, and air was introduced for reaction. After 6 h, most of the solvent was removed under reduced pressure, water was added and stirred, a large amount of product precipitated, the pH value was adjusted to 5 with sodium hydroxide solution, and stirring was continued for 1 h. 19.68 g of 1-(4-chlorophenyl)-3-pyrazolol was obtained by filtration. The product yield was 96.3% and the purity was 98.6%. The synthesis route of the comparative example was the same as that of the example.

[0018] Example 2: 20 g of 1-ethyl-3-methylimidazolium chloroacetate cobalt salt [C 2 mim][CoClAc] ionic liquid and 1 g of 1-(4-chlorophenyl)pyrazolidin-3-one were put into a reaction kettle equipped with magnetic stirring, a thermometer and a gas distributor. When the materials in the kettle were heated to 70 °C, air was introduced at a flow rate of 20 L / min, and the mixture was stirred and reacted at a constant temperature for 6 h. After the reaction was completed, the reaction kettle was quickly cooled to room temperature in a water bath. The product 1-(4-chlorophenyl)-3-pyrazolol was extracted 3 times with toluene as the extractant having the same volume as the reaction mixture. After the extractive solutions were combined and the extractant was recovered by distillation under reduced pressure, the product 1-(4-chlorophenyl)-3-pyrazolol was obtained. Its yield was 99.0%, purity was 99.4%, and the raffinate was the ionic liquid, which could be directly recycled.

[0019] Example 3: 1-ethyl-3-methylimidazolium chloroferric [C 2 mim]Cl][FeCl3 15 g of ionic liquid and 1 g of 1-(4-chlorophenyl)pyrazolidin-3-one were put into a reaction kettle equipped with magnetic stirring, a thermometer and a gas distributor. When the materials in the kettle were heated to 70 °C, air was introduced at a flow rate of 30 L / min, and the mixture was stirred while maintaining the temperature for 7 h. After the reaction was completed, the reaction kettle was quickly cooled to room temperature in a water bath. The product 1-(4-chlorophenyl)-3-pyrazolol was extracted 3 times with methyl isobutyl ketone, an extractant with the same volume as the reaction mixture. After combining the extractive solutions and recovering the extractant by vacuum distillation, the product 1-(4-chlorophenyl)-3-pyrazolol was obtained. Its yield was 99.1%, and its purity was 99.3%. The raffinate was ionic liquid and could be directly recycled.

[0020] Example 4: 1-Butyl-3-methylimidazolium chloride-iron(III) chloride salt [C 4 mimCl][FeCl 3 15 g of ionic liquid and 1 g of 1-(4-chlorophenyl)pyrazolidin-3-one were put into a reaction kettle equipped with magnetic stirring, a thermometer and a gas distributor. When the materials in the kettle were heated to 80 °C, air was introduced at a flow rate of 40 L / min, and the mixture was stirred while maintaining the temperature for 8 h. After the reaction was completed, the reaction kettle was quickly cooled to room temperature in a water bath. The product 1-(4-chlorophenyl)-3-pyrazolol was extracted 3 times with tetrahydrofuran, an extractant with the same volume as the reaction mixture. After combining the extractive solutions and recovering the extractant by vacuum distillation, the product 1-(4-chlorophenyl)-3-pyrazolol was obtained. Its yield was 99.0%, and its purity was 99.3%. The raffinate was ionic liquid and could be directly recycled.

[0021] Example 5: 1-Ethyl-3-methylimidazolium chloride-manganese(II) acetate salt [C 2 mim][MnClAc] 10 g of ionic liquid and 1 g of 1-(4-chlorophenyl)pyrazolidin-3-one were put into a reaction kettle equipped with magnetic stirring, a thermometer and a gas distributor. When the materials in the kettle were heated to 60 °C, air was introduced at a flow rate of 20 L / min, and the mixture was stirred while maintaining the temperature for 5 h. After the reaction was completed, the reaction kettle was quickly cooled to room temperature in a water bath. The product 1-(4-chlorophenyl)-3-pyrazolol was extracted 3 times with toluene, an extractant with the same volume as the reaction mixture. After combining the extractive solutions and recovering the extractant by vacuum distillation, the product 1-(4-chlorophenyl)-3-pyrazolol was obtained. Its yield was 98.3%, and its purity was 98.9%. The raffinate was ionic liquid and could be directly recycled.

[0022] Example 6: 1-Butyl-3-methylimidazolium chloride-manganese(II) acetate salt [C 420 g of [mim][MnClAc] ionic liquid and 1 g of 1-(4-chlorophenyl)pyrazolidin-3-one were put into a reaction kettle equipped with a magnetic stirrer, a thermometer and a gas distributor. When the materials in the kettle were heated to 70 °C, air was introduced at a flow rate of 20 L / min, and the mixture was kept warm and stirred for 6 h. After the reaction was completed, the reaction kettle was quickly cooled to room temperature in a water bath. The product 1-(4-chlorophenyl)-3-pyrazolol was extracted 3 times with toluene, an extractant with the same volume as the reaction mixture. After combining the extracts and recovering the extractant by vacuum distillation, the product 1-(4-chlorophenyl)-3-pyrazolol was obtained. Its yield was 98.5%, and its purity was 99.2%. The raffinate was an ionic liquid and could be directly recycled.

[0023] Example 7: 15 g of 1-ethyl-3-methylimidazolium chloro-cobalt acetate [C 2 mim][CoClAc] ionic liquid and 1 g of 1-(4-chlorophenyl)pyrazolidin-3-one were put into a reaction kettle equipped with a magnetic stirrer, a thermometer and a gas distributor. When the materials in the kettle were heated to 70 °C, air was introduced at a flow rate of 30 L / min, and the mixture was kept warm and stirred for 7 h. After the reaction was completed, the reaction kettle was quickly cooled to room temperature in a water bath. The product 1-(4-chlorophenyl)-3-pyrazolol was extracted 3 times with methyl isobutyl ketone, an extractant with the same volume as the reaction mixture. After combining the extracts and recovering the extractant by vacuum distillation, the product 1-(4-chlorophenyl)-3-pyrazolol was obtained. Its yield was 98.9%, and its purity was 99.1%. The raffinate was an ionic liquid and could be directly recycled.

[0024] Example 8: 15 g of 1-butyl-3-methylimidazolium chloro-cobalt acetate [C 4 mim][CoClAc] ionic liquid and 1 g of 1-(4-chlorophenyl)pyrazolidin-3-one were put into a reaction kettle equipped with a magnetic stirrer, a thermometer and a gas distributor. When the materials in the kettle were heated to 80 °C, air was introduced at a flow rate of 40 L / min, and the mixture was kept warm and stirred for 8 h. After the reaction was completed, the reaction kettle was quickly cooled to room temperature in a water bath. The product 1-(4-chlorophenyl)-3-pyrazolol was extracted 3 times with tetrahydrofuran, an extractant with the same volume as the reaction mixture. After combining the extracts and recovering the extractant by vacuum distillation, the product 1-(4-chlorophenyl)-3-pyrazolol was obtained. Its yield was 99.1%, and its purity was 99.2%. The raffinate was an ionic liquid and could be directly recycled.

[0025] Example 9: The 1-butyl-3-methylimidazolium chloro-cobalt acetate [C 4The [mim][CoClAc] ionic liquid was directly used for recycling. 1 g of the ionic liquid and 1-(4-chlorophenyl)pyrazolidin-3-one were put into a reaction kettle equipped with a magnetic stirrer, a thermometer and a gas distributor. When the materials in the kettle were heated to 70 °C, air was introduced at a flow rate of 20 L / min, and the reaction was carried out with heat preservation and stirring for 6 h. After the reaction was completed, the reaction kettle was quickly cooled to room temperature in a water bath. The product 1-(4-chlorophenyl)-3-pyrazolol was extracted 3 times with toluene as the extractant having the same volume as the reaction mixture. After the extractive solutions were combined and the extractant was recovered by distillation under reduced pressure, the product 1-(4-chlorophenyl)-3-pyrazolol was obtained. After the ionic liquid was reused 5 times, the yield of the obtained product was 99.3%, and the purity was 99.4%. After the ionic liquid was reused 10 times, the yield of the obtained product was 99.0%, and the purity was 99.2%.

[0026] Example 10: The 1-ethyl-3-methylimidazolium chloro-cobalt acetate [C 2 The [mim][CoClAc] ionic liquid was directly used for recycling. 1 g of the ionic liquid and 1-(4-chlorophenyl)pyrazolidin-3-one were put into a reaction kettle equipped with a magnetic stirrer, a thermometer and a gas distributor. When the materials in the kettle were heated to 70 °C, air was introduced at a flow rate of 20 L / min, and the reaction was carried out with heat preservation and stirring for 6 h. After the reaction was completed, the reaction kettle was quickly cooled to room temperature in a water bath. The product 1-(4-chlorophenyl)-3-pyrazolol was extracted 3 times with toluene as the extractant having the same volume as the reaction mixture. After the extractive solutions were combined and the extractant was recovered by distillation under reduced pressure, the product 1-(4-chlorophenyl)-3-pyrazolol was obtained. After the ionic liquid was reused 5 times, the yield of the obtained product was 99.1%, and the purity was 99.3%. After the ionic liquid was reused 10 times, the yield of the obtained product was 98.7%, and the purity was 99.3%.

Claims

1. A method for preparing 1-(4-chlorophenyl)-3-pyrazolol, characterized in that The invention adopts an ionic liquid as a solvent and a catalyst to dissolve and catalyze the air oxidation reaction of 1-(4-chlorophenyl)pyrazolidine-3-one to prepare 1-(4-chlorophenyl)-3-pyrazolol. The mass ratio of 1-(4-chlorophenyl)pyrazolidine-3-one to the ionic liquid is 1:20-1:10, the air flow rate is 20-40 L / min, the reaction temperature is 50-80°C, the reaction time is 5-8 hours, and after the reaction is completed, the product 1-(4-chlorophenyl)-3-pyrazolol is extracted three times with an extractant having an equal volume to the reaction mixture. The extracts are combined and the extractant is recovered by vacuum distillation to obtain the product 1-(4-chlorophenyl)-3-pyrazolol. The product yield is 98.0%-99.2%, the purity is 98.9%-99.6%, and the raffinate is an ionic liquid. The ionic liquid is one of 1-ethyl-3-methylimidazolium chloride-ferric chloride [C2mimCl][FeCl3], 1-butyl-3-methylimidazolium chloride-ferric chloride salt [C4mim]Cl][FeCl3], 1-ethyl-3-methylimidazolium chloride-manganese acetate salt [C2mim][MnClAc], 1-butyl-3-methylimidazolium chloride-manganese acetate salt [C4mim][MnClAc], 1-ethyl-3-methylimidazolium chloride-cobalt acetate salt [C2mim][CoClAc], 1-butyl-3-methylimidazolium chloride-cobalt acetate salt [C4mim][CoClAc]; the extractant is one of toluene, methyl isobutyl ketone or tetrahydrofuran.