Method for preparing 1-(4-chlorphenyl)-3-pyrazole alcohol

Abstract

A method for preparing 1-(4-chlorphenyl)-3-pyrazole alcohol is characterized in that an ionic liquid is adopted as a solvent and a catalyst, 1-(4-chlorphenyl) pyrazolidine-3-ketone is dissolved and catalyzed to be subjected to an air oxidation reaction to prepare the 1-(4-chlorphenyl)-3-pyrazole alcohol, the mass ratio of the 1-(4-chlorphenyl) pyrazolidine-3-ketone to the ionic liquid is 1: 20-1: 10, the air flow rate is 20-40 L / min, the reaction time is 2-4 hours, and the reaction time is 1-4 hours. The reaction temperature is 50-80 DEG C, the reaction time is 5-8 hours, after the reaction is finished, the product 1-(4-chlorphenyl)-3-pyrazole alcohol is extracted by using an extracting agent, extracting solutions are combined, the extracting agent is recovered through reduced pressure distillation, the product 1-(4-chlorphenyl)-3-pyrazole alcohol is obtained, the yield is 98.0%-99.2%, the purity is 98.9%-99.6%, and raffinate is ionic liquid. The method has the characteristics of mild reaction conditions, simplicity and convenience in operation and high product yield; the ionic liquid has dual functions of a solvent and a catalyst, and the reaction efficiency is improved through the synergistic effect of the solvent and the catalyst; the ionic liquid has proper L acid strength, so that side reactions such as excessive oxidation and decomposition of the product are avoided; the ionic liquid is easy to separate from the product, and the active center is not lost and can be repeatedly used.

Description

Technical Field

[0001] The invention relates to the field of fine organic synthesis, and in particular to a method for preparing 1-(4-chlorophenyl)-3-pyrazolol by using ionic liquid as solvent and catalyst to dissolve and catalyze the air oxidation reaction of 1-(4-chlorophenyl)pyrazolidine-3-one. Background Art

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

[0003] Air is a clean and cheap oxidant. The use of catalytic air to oxidize 1-(4-chlorophenyl)pyrazolidine-3-one to prepare 1-(4-chlorophenyl)-3-pyrazolol can avoid the safety hazards caused by hydrogen peroxide as an oxidant, increase the yield of 1-(4-chlorophenyl)-3-pyrazolol, reduce raw material costs, improve economic benefits, reduce wastewater generation, and achieve clean production. 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 alkaline solution. The reason is that the raw material 1-(4-chlorophenyl)pyrazolidin-3-one is soluble in alkaline solution. The oxidation reaction of 1-(4-chlorophenyl)pyrazolidin-3-one is realized in a homogeneous system. This technology has the disadvantages of large alkali consumption and the need for neutralization with acidic substances after the reaction. In addition, under acidic conditions, the product 1-(4-chlorophenyl)-3-pyrazolol is very prone to dehydration side reactions, resulting in low product yield, poor quality, and a large amount of salt-containing wastewater discharge.

[0004] As solvents and catalysts, ionic liquids have outstanding properties such as good solubility, high catalytic activity and selectivity, designability, good stability, and easy recovery and recycling. These properties make ionic liquids play an increasingly important role in chemical industrial production and environmental protection. Therefore, the present invention applies for a method for preparing 1-(4-chlorophenyl)-3-pyrazolol, characterized in that ionic liquids are used as solvents and catalysts to dissolve and catalyze the air oxidation reaction of 1-(4-chlorophenyl)pyrazolidine-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)pyrazolidine-3-one, providing a basis for the rapid oxidation of the raw material in 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 contact with the raw materials, providing more reaction sites for the oxidation reaction, and the synergistic effect of the two improves the efficiency of the reaction; the appropriate L acid strength of the ionic liquid avoids side reactions such as excessive oxidation and decomposition of the product; in addition, after the reaction, the ionic liquid is easy to separate from the product and can be reused. The present invention is a technical innovation in the green production process of 1-(4-chlorophenyl)-3-pyrazolol, and particularly achieves breakthroughs in the use of more environmentally friendly and efficient catalysts and solvents and in the optimization of reaction conditions, and has important academic significance and potential application prospects. Summary of the invention

[0005] The purpose of the present invention is to replace the preparation method of 1-(4-chlorophenyl)-3-pyrazolol in the traditional oxidant hydrogen peroxide system, develop a method for preparing 1-(4-chlorophenyl)-3-pyrazolol by oxidation under mild reaction conditions using air as an oxidant, and solve the problems of consuming a large amount of reducing agent to reduce excess hydrogen peroxide after the reaction of the traditional hydrogen peroxide oxidant system, large amount of wastewater discharge, and the inability to reuse the catalyst.

[0006] A method for preparing 1-(4-chlorophenyl)-3-pyrazolol, 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)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 5-8h, 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, and the extracts are combined and the extractant is recovered by vacuum distillation to obtain the product 1-(4-chlorophenyl)-3-pyrazolol, and the yield is 98.0%-99.2% and the purity is 98.9% ~99.6%, the raffinate is an ionic liquid and can be directly recycled; the ionic liquid is one of 1-ethyl-3-methylimidazolium chloride-ferric chloride [C2mimCl][FeCl3], 1-butyl-3-methylimidazolium chloride-ferric chloride salt [C4mimCl][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.

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

[0008] The specific technical solution is illustrated by taking 1-butyl-3-methylimidazolium chloride-acetic acid cobalt salt [C4mim][CoClAc] ionic liquid as an example.

[0009] 15 g of [C4mim][CoClAc] 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 reaction was stirred and kept warm for 6 hours. After the reaction, the reactor was quickly cooled to room temperature in a water bath, and the product 1-(4-chlorophenyl)-3-pyrazolol was extracted 3 times with an extractant of toluene having an equal volume to the reaction mixture. The extracts were combined and the extractant was recovered by reduced pressure distillation to obtain the product 1-(4-chlorophenyl)-3-pyrazolol with a yield of 99.2% and a purity of 99.6%. The raffinate was an ionic liquid and could be directly recycled.

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

[0011] 1. Mild reaction conditions, simple operation, high product yield and purity.

[0012] 2. Ionic liquids have the dual functions of solvents and catalysts, and the synergistic effect of the two improves the efficiency of the reaction.

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

[0014] 4. Ionic liquids are easy to separate from products, active centers are not lost and can be reused. Specific implementation methods

[0016] The method of the present invention is further described below in conjunction with embodiments, which are not intended to limit the present invention.

[0017] Example 1: 10 g of 1-butyl-3-methylimidazolium chloro-acetic acid cobalt salt [C4mim][CoClAc] ionic liquid and 1 g of 1-(4-chlorophenyl)pyrazolidine-3-one were put into a reactor equipped with a magnetic stirrer, a thermometer and a gas distributor. When the materials in the reactor were heated to 70°C, air was introduced at a flow rate of 20 L / min, and the reaction was stirred and kept warm for 6 hours. After the reaction, the reactor was quickly cooled to room temperature in a water bath, and the product 1-(4-chlorophenyl)-3-pyrazolol was extracted 3 times with an extractant of toluene equal to the volume of the reaction mixture. The extracts were combined and the extractant was recovered by vacuum distillation to obtain the product 1-(4-chlorophenyl)-3-pyrazolol, with a yield of 99.0% and a purity of 99.3%. The raffinate was an ionic liquid and could be directly recycled.

[0018] Comparative Example 1: This comparative example provides a method for preparing 1-(4-chlorophenyl)-3-pyrazole alcohol. The difference between the comparative example and the embodiment is that the comparative example does not use ionic liquid as solvent and catalyst, but uses formic acid as solvent and ferric chloride as catalyst. The specific amounts are as follows: 90g of formic acid is added to a reactor, 20g of 1-(4-chlorophenyl)pyrazolidine-3-one and 1.6g of ferric chloride are added under stirring, the temperature is raised to 90°C, and air is passed to react. After 6h, most of the solvent is removed under reduced pressure, water is added and stirred, a large amount of product is precipitated, the pH value is adjusted to 5 with sodium hydroxide solution, stirring is continued for 1h, and 19.68g of 1-(4-chlorophenyl)-3-pyrazole alcohol is obtained by filtration. The product yield is 96.3% and the purity is 98.6%. The synthetic route of the comparative example is consistent with that of the embodiment.

[0019] Example 2: 1-ethyl-3-methylimidazolium chloro-cobalt acetate [C2mim][CoClAc] ionic liquid 20g, 1-(4-chlorophenyl)pyrazolidine-3-one 1g was put into a reactor equipped with a magnetic stirrer, a thermometer and a gas distributor. When the materials in the reactor were heated to 70°C, air was introduced at a flow rate of 20L / min, and the reaction was stirred and kept warm for 6h. After the reaction, the reactor was rapidly cooled to room temperature in a water bath, and the product 1-(4-chlorophenyl)-3-pyrazolol was extracted 3 times with an extractant of toluene equal to the volume of the reaction mixture. The extracts were combined and the extractant was recovered by distillation under reduced pressure to obtain the product 1-(4-chlorophenyl)-3-pyrazolol, with a yield of 99.0% and a purity of 99.4%. The raffinate was an ionic liquid and could be directly recycled.

[0020] Example 3: 15 g of 1-ethyl-3-methylimidazolium chloride-ferric chloride [C2mim]Cl][FeCl3] ionic liquid and 1 g of 1-(4-chlorophenyl)pyrazolidine-3-one were put into a reactor equipped with a magnetic stirrer, a thermometer and a gas distributor. When the materials in the reactor were heated to 70°C, air was introduced at a flow rate of 30 L / min, and the reaction was stirred and kept warm for 7 hours. After the reaction, the reactor was quickly cooled to room temperature in a water bath, and the product 1-(4-chlorophenyl)-3-pyrazolol was extracted 3 times with an extractant methyl isobutyl ketone having an equal volume to the reaction mixture. The extracts were combined and the extractant was recovered by vacuum distillation to obtain the product 1-(4-chlorophenyl)-3-pyrazolol, with a yield of 99.1% and a purity of 99.3%. The raffinate was an ionic liquid and could be directly recycled.

[0021] Example 4: 15 g of 1-butyl-3-methylimidazolium chloride-ferric chloride salt [C4mimCl][FeCl3] ionic liquid and 1 g of 1-(4-chlorophenyl)pyrazolidine-3-one were put into a reactor equipped with a magnetic stirrer, a thermometer and a gas distributor. When the materials in the reactor were heated to 80°C, air was introduced at a flow rate of 40 L / min, and the reaction was stirred and kept warm for 8 hours. After the reaction, the reactor was quickly cooled to room temperature in a water bath, and the product 1-(4-chlorophenyl)-3-pyrazolol was extracted 3 times with an extractant of tetrahydrofuran equal to the volume of the reaction mixture. The extracts were combined and the extractant was recovered by vacuum distillation to obtain the product 1-(4-chlorophenyl)-3-pyrazolol, with a yield of 99.0% and a purity of 99.3%. The raffinate was an ionic liquid and could be directly recycled.

[0022] Example 5: 10 g of 1-ethyl-3-methylimidazolium chloride-acetic acid manganese salt [C2mim][MnClAc] ionic liquid and 1 g of 1-(4-chlorophenyl)pyrazolidine-3-one were put into a reactor equipped with a magnetic stirrer, a thermometer and a gas distributor. When the materials in the reactor were heated to 60°C, air was introduced at a flow rate of 20 L / min, and the reaction was stirred and kept warm for 5 hours. After the reaction, the reactor was quickly cooled to room temperature in a water bath, and the product 1-(4-chlorophenyl)-3-pyrazolol was extracted 3 times with an extractant of toluene equal to the volume of the reaction mixture. The extracts were combined and the extractant was recovered by vacuum distillation to obtain the product 1-(4-chlorophenyl)-3-pyrazolol, with a yield of 98.3% and a purity of 98.9%. The raffinate was an ionic liquid and could be directly recycled.

[0023] Example 6: 20 g of 1-butyl-3-methylimidazolium chloride-acetic acid manganese salt [C4mim][MnClAc] ionic liquid and 1 g of 1-(4-chlorophenyl)pyrazolidine-3-one were put into a reactor equipped with a magnetic stirrer, a thermometer and a gas distributor. When the materials in the reactor were heated to 70°C, air was introduced at a flow rate of 20 L / min, and the reaction was stirred and kept warm for 6 hours. After the reaction, the reactor was quickly cooled to room temperature in a water bath, and the product 1-(4-chlorophenyl)-3-pyrazolol was extracted 3 times with an extractant of toluene equal to the volume of the reaction mixture. The extracts were combined and the extractant was recovered by vacuum distillation to obtain the product 1-(4-chlorophenyl)-3-pyrazolol, with a yield of 98.5% and a purity of 99.2%. The raffinate was an ionic liquid and could be directly recycled.

[0024] Example 7: 15 g of 1-ethyl-3-methylimidazolium chloro-acetic acid cobalt salt [C2mim][CoClAc] ionic liquid and 1 g of 1-(4-chlorophenyl)pyrazolidine-3-one were put into a reactor equipped with a magnetic stirrer, a thermometer and a gas distributor. When the materials in the reactor were heated to 70°C, air was introduced at a flow rate of 30 L / min, and the reaction was stirred and kept warm for 7 hours. After the reaction, the reactor was quickly cooled to room temperature in a water bath, and the product 1-(4-chlorophenyl)-3-pyrazolol was extracted 3 times with an extractant methyl isobutyl ketone having an equal volume to the reaction mixture. The extracts were combined and the extractant was recovered by distillation under reduced pressure to obtain the product 1-(4-chlorophenyl)-3-pyrazolol, with a yield of 98.9% and a purity of 99.1%. The raffinate was an ionic liquid and could be directly recycled.

[0025] Example 8: 15 g of 1-butyl-3-methylimidazolium chloro-acetic acid cobalt salt [C4mim][CoClAc] ionic liquid and 1 g of 1-(4-chlorophenyl)pyrazolidine-3-one were put into a reactor equipped with a magnetic stirrer, a thermometer and a gas distributor. When the materials in the reactor were heated to 80°C, air was introduced at a flow rate of 40 L / min, and the reaction was stirred and kept warm for 8 hours. After the reaction, the reactor was quickly cooled to room temperature in a water bath, and the product 1-(4-chlorophenyl)-3-pyrazolol was extracted 3 times with an extractant of tetrahydrofuran equal to the volume of the reaction mixture. The extracts were combined and the extractant was recovered by vacuum distillation to obtain the product 1-(4-chlorophenyl)-3-pyrazolol, with a yield of 99.1% and a purity of 99.2%. The raffinate was an ionic liquid and could be directly recycled.

[0026] Example 9: The 1-butyl-3-methylimidazolium chloro-cobalt acetate [C4mim][CoClAc] ionic liquid recovered in Example 1 was directly used for recycling. The ionic liquid and 1-(4-chlorophenyl)pyrazolidine-3-one 1g were put into a reactor equipped with a magnetic stirrer, a thermometer and a gas distributor. When the materials in the reactor were heated to 70°C, air was introduced at a flow rate of 20L / min, and the reaction was stirred and kept warm for 6h. After the reaction, the reactor was quickly cooled to room temperature in a water bath, and the product 1-(4-chlorophenyl)-3-pyrazolol was extracted 3 times with an extractant of toluene equal to the volume of the reaction mixture. The extracts were combined and the extractant was recovered by vacuum distillation to obtain the product 1-(4-chlorophenyl)-3-pyrazolol; 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%.

[0027] Example 10: The 1-ethyl-3-methylimidazolium chloro-cobalt acetate [C2mim][CoClAc] ionic liquid recovered in Example 2 was directly used for recycling. The ionic liquid and 1-(4-chlorophenyl)pyrazolidine-3-one 1g were put into a reactor equipped with a magnetic stirrer, a thermometer and a gas distributor. When the materials in the reactor were heated to 70°C, air was introduced at a flow rate of 20L / min, and the reaction was stirred and kept warm for 6h. After the reaction, the reactor was rapidly cooled to room temperature in a water bath, and the product 1-(4-chlorophenyl)-3-pyrazolol was extracted 3 times with an extractant of toluene equal to the volume of the reaction mixture. The extracts were combined and the extractant was recovered by distillation under reduced pressure to obtain the product 1-(4-chlorophenyl)-3-pyrazolol; after the ionic liquid was reused 5 times, the yield of the product obtained was 99.1% and the purity was 99.3%; after the ionic liquid was reused 10 times, the yield of the product obtained 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.