A simple preparation method of p-chlorophenol

Abstract

The present application relates to a simple preparation method of p-chlorophenol, which comprises the following steps: putting phenol into a four-necked flask, adding dichloromethane, stirring and dissolving, then adding a catalyst, slowly dropping chlorinating reagent, pouring the solution in the four-necked flask into a quenching kettle after the reaction is completed, adding water again, separating layers, discarding the water layer, removing dichloromethane to obtain a crude p-chlorophenol, wherein the weight ratio of raw materials is catalyst: phenol: water: chlorinating reagent: dichloromethane = 1:120:40:172:780; sending the crude product into a rectification kettle for rectification, receiving main fraction p-chlorophenol when the tower top is 65 DEG C; the yield is 82%, and the purity is 99.6%. The advantages are that p-chlorophenol is synthesized by taking phenol as a starting raw material and taking sulfuryl chloride as a chlorinating reagent at a temperature of 40-50 DEG C; the method is reasonable, the operation is simple, the yield is high, and the purity meets the quality research requirements. By rechlorination, the by-product o-chlorophenol can be changed into 2,4-dichlorophenol, and the by-product can be used for production.

Description

Technical Field

[0001] This invention relates to the field of organic synthesis technology, and specifically to a simple method for preparing p-chlorophenol. Background Technology

[0002] p-Chlorophenol is an important organic compound with a wide range of applications. However, existing synthetic methods suffer from low yields, numerous byproducts, and low purity, which restricts its large-scale application. Therefore, developing an efficient and environmentally friendly synthetic method and corresponding purification process is of great significance for expanding the application areas of p-chlorophenol. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention proposes a simple method for preparing p-chlorophenol. The process is ingenious, the steps are complete, it is simple and easy to operate, the yield is high, and the purity meets the requirements for quality research.

[0004] The technical solution of this invention:

[0005] A simple method for preparing p-chlorophenol includes the following steps: phenol is added to a four-necked flask, dichloromethane is added, and the mixture is stirred to dissolve. A catalyst is then added, and a chlorinating agent is slowly added dropwise while maintaining the temperature at 20-80°C. The reaction is carried out for 1-10 hours. After the reaction is complete, the solution in the four-necked flask is poured into a quenching vessel, and water is added. The mixture separates into layers, the aqueous layer is discarded, and the organic phase is depressurized to -0.1 MPa while maintaining the temperature at 50°C ± 5°C to remove dichloromethane, yielding crude p-chlorophenol. The weight ratio of the raw materials is as follows: The ratio of catalyst: phenol: water: chlorination reagent: chloroform = 1:120:40:172:780; the crude product is fed into a distillation kettle for distillation, with a vacuum of 20-30 mmHg and the temperature at the bottom of the kettle controlled between 70-130℃; before the temperature at the top of the column reaches 65℃, the fore-distillate is collected and enters a re-chlorination kettle for later use; after the temperature at the top of the column reaches 65℃, the main fraction, p-chlorophenol, is collected. After collection, the distillation operation is completed and the temperature is lowered; the yield is 82% and the purity is 99.6%.

[0006] The chlorination reagent is sulfonyl chloride, chlorine gas, or thionyl chloride, with sulfonyl chloride being preferred.

[0007] The catalyst is ferric chloride or aluminum chloride, with ferric chloride being preferred.

[0008] The reaction temperature is 40~50℃.

[0009] The reaction time is 2-3 hours.

[0010] The fore-distillate is fed into a distillation vessel for distillation. The fore-distillate is mixed with chlorine gas at a weight ratio of 4:1. Chlorine gas is introduced into the fore-distillate, and the temperature is controlled at 25~35℃. A solid is precipitated, filtered, and the by-product 2,4-dichlorophenol with a purity of 98.5% is obtained.

[0011] The advantages of this invention are that it designs a selective catalytic synthesis of o-chlorophenol, using phenol as the starting material and sulfonyl chloride as the chlorinating agent, at a temperature of 40-50℃ to synthesize p-chlorophenol. This method is reasonable, simple, easy to operate, has a high yield, and the purity meets quality research requirements. The byproduct o-chlorophenol is further chlorinated to obtain 2,4-dichlorophenol, which is then utilized in production. Detailed Implementation

[0012] All features disclosed in this specification, or steps in all methods or processes disclosed herein, may be combined in any way, except for mutually exclusive features and / or steps.

[0013] This invention relates to the synthesis, preparation, and purification methods of o-chlorophenol, as well as the recovery of waste gas and reuse of byproducts. The invention designs a selective catalytic synthesis of o-chlorophenol, using phenol as the starting material and sulfonyl chloride as the chlorinating agent, at a temperature of 40-50°C to synthesize p-chlorophenol. The byproduct o-chlorophenol is then re-chlorinated to obtain 2,4-dichlorophenol.

[0014] This method is reasonable, simple, easy to operate, has a high yield, and the purity meets the requirements for quality research.

[0015] Main reaction:

[0016]

[0017] Side reactions:

[0018] Chlorination side reaction: 1)

[0020] 2)

[0022] Example 1

[0023] Phenol (60 g, 0.64 mol) was added to a four-necked flask, followed by 300 mL of dichloromethane. The mixture was stirred until dissolved, then 0.5 g of ferric chloride was added. Sulfonyl chloride (86 g, 0.64 mmol) was slowly added dropwise, maintaining the temperature at 30–40 °C for 2 hours. After the reaction was complete, 20 g of water was added, and the mixture was allowed to separate into two layers. The aqueous layer was discarded. The organic phase was depressurized to -0.1 MPa, and the temperature was maintained at approximately 50 °C to remove dichloromethane, yielding 81 g of crude p-chlorophenol. The vacuum level was 20–30 mmHg, and the temperature at the bottom of the distillation vessel was maintained between 70–130 °C. Before the temperature at the top of the column reached 65 °C, the foredistillate was collected and transferred to a rechlorination vessel for later use. Once the temperature at the top of the column reached 65 °C, the main fraction of p-chlorophenol was collected. After collection, the distillation operation was completed, and the temperature was lowered. The yield was 82%, and the purity was 99.6% (GC, calculated using the area normalization method). Example 2

[0024] Phenol (60 g, 0.64 mol) was added to a four-necked flask, followed by 300 mL of dichloromethane. The mixture was stirred until dissolved, then 0.5 g of ferric chloride was added. Sulfonyl chloride (86 g, 0.64 mmol) was slowly added dropwise, maintaining the temperature at 40–50 °C for 2 hours. After the reaction was complete, 20 g of water was added, and the mixture was allowed to separate into two layers. The aqueous layer was discarded. The organic phase was depressurized to -0.1 MPa, and the temperature was maintained at approximately 50 °C to remove dichloromethane, yielding 81 g of crude p-chlorophenol. The vacuum level was 20–30 mmHg, and the temperature at the bottom of the distillation vessel was maintained between 70–130 °C. Before the temperature at the top of the column reached 65 °C, the foredistillate was collected and transferred to a rechlorination vessel for later use. Once the temperature at the top of the column reached 65 °C, the main fraction of p-chlorophenol was collected. After collection, the distillation operation was completed, and the temperature was lowered. The yield was 85%, and the purity was 99.7% (GC, calculated using the area normalization method).

[0025] Example 3.

[0026] Rechlorination:

[0027]

[0028] The fore-distillate from Example 2 was subjected to distillation. 40g of the distilled fore-distillate was passed through 10g of chlorine gas and the temperature was controlled at 25~35℃. A solid precipitated out and was filtered to obtain 35g of the byproduct 2,4-dichlorophenol with a purity of 98.5% (GC, calculated by area normalization method).

Claims

1. A simple method for preparing p-chlorophenol, characterized by, The specific steps are as follows: phenol is put into a four-necked flask, dichloromethane is added, stirring and dissolving, a catalyst is added, a chlorinating reagent is slowly added dropwise, the temperature is controlled at 20-80℃, and the dropwise reaction is carried out for 1-10 hours; after the reaction is completed, the solution in the four-necked flask is poured into a quenching kettle, water is further added, the layers are separated, the water layer is discarded, the organic phase is reduced to-0.1 MPa, the temperature is controlled at 50℃±5℃, dichloromethane is removed to obtain a crude p-chlorophenol, wherein the weight ratio of the raw materials is catalyst: phenol: water: chlorinating reagent: chloroform = 1:120:40:172:780; the crude product is sent to a rectification kettle for rectification, the vacuum degree in the rectification kettle is 20-30 mmHg, and the temperature at the bottom of the rectification kettle is controlled at 70-130℃; before the overhead temperature is 65℃, the front fraction is received, the front fraction is put into a re-chlorination kettle, and is ready for use; after the overhead is 65℃, the main fraction p-chlorophenol is received, after the receiving is completed, the rectification operation is ended and the temperature is lowered; the yield is 82%, and the purity is 99.6%; the chlorinating reagent is sulfuryl chloride; the catalyst is ferric chloride; the reaction temperature is 40-50℃; the reaction time is 2-3 hours; the front fraction is sent to a rectification kettle for rectification, the front fraction and chlorine gas are operated according to a weight ratio of 4:1, chlorine gas is introduced into the front fraction, the temperature is controlled at 25-35℃, a solid is precipitated, filtration is carried out, and a by-product 2,4-dichlorophenol is obtained, and the purity is 98.5%.

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