A method for synthesizing 1,2,3,4-tetrachlorobutane

Abstract

The application provides a synthesis method of 1,2,3,4-tetrachlorobutane and belongs to the technical field of organic synthesis. The synthesis method comprises the following steps: mixing 1,3-butadiene and halogenated alkane in a protective gas environment to obtain a mixture; introducing liquid chlorine into a sealed environment filled with the protective gas, and then adding the mixture into the liquid chlorine dropwisely at 30-40 DEG C to obtain 1,2,3,4-tetrachlorobutane. The reaction environment in the whole synthesis process is safe, a large amount of waste water is not generated, a large amount of chlorine waste gas is not generated, the raw material conversion rate is high, and the product yield is high and stable.

Description

Technical Field

[0001] This invention relates to the field of organic synthesis technology, and specifically to a method for synthesizing 1,2,3,4-tetrachlorobutane. Background Technology

[0002] 1,2,3,4-Tetrachlorobutane, with the molecular formula C4H6Cl4, is a meso compound of an organohalogenated hydrocarbon, appearing as white crystals. Tetrachlorobutane is somewhat toxic, insoluble in water, but readily soluble in organic solvents.

[0003] Currently, 1,2,3,4-tetrachlorobutane is mainly prepared by reacting chlorine with 1,3-butadiene. The synthesis process involves using dichloromethane as a solvent, slowly introducing chlorine gas to react with 1,3-butadiene, and then filtering, washing, and separating the chlorine gas to obtain qualified 1,2,3,4-tetrachlorobutane. For example, Chinese patent document CN108774103A discloses a method for producing 1,2,3,4-tetrachlorobutane, in which chlorine and gaseous 1,3-butadiene are simultaneously introduced into dichloromethane, and the reaction is carried out under catalytic conditions to obtain a mixture containing 1,2,3,4-tetrachlorobutane. The main drawback of the above process is that 1,3-butadiene is directly introduced into the reaction, and 1,3-butadiene is extremely unstable and prone to explosion and combustion. Furthermore, the reaction requires a relatively large amount of chlorine, resulting in significant wastewater from subsequent tail gas treatment.

[0004] The literature (Synthesis and Purification of Meso-1,2,3,4-Tetrachlorobutane [D], Du Gang, Tianjin University, 2007) discloses a one-step synthesis process for Meso-1,2,3,4-tetrachlorobutane. The optimal process conditions are: dichloromethane dosage of 11.31% of the total height of the bubble column, reactant ratio n(chlorine):n(butadiene) = 5:1, reaction temperature of 10℃, atmospheric pressure reaction, reaction time of 5h, and pyridine catalyst dosage of 5% of the mass of dichloromethane. Under these conditions, the product yield is 57.6%. However, even with a catalyst, the yield remains low when dichloromethane is used as a solvent and chlorine is introduced to react with 1,3-butadiene. Summary of the Invention

[0005] In view of this, the present invention provides a method for synthesizing 1,2,3,4-tetrachlorobutane. The entire synthesis process is environmentally safe, does not generate a large amount of wastewater or chlorine gas, has a high raw material conversion rate, and produces a high and stable product yield.

[0006] To achieve the above objectives, the present invention provides a method for synthesizing 1,2,3,4-tetrachlorobutane, comprising the following steps: (1) Under a protective gas environment, 1,3-butadiene was mixed with haloalkanes to obtain a mixture; (2) Liquid chlorine is introduced into a sealed environment filled with protective gas, and then a mixture is added dropwise to the liquid chlorine at 30-40°C to react and obtain 1,2,3,4-tetrachlorobutane.

[0007] The protective gas is nitrogen, argon, etc., which replaces air. 1,3-Butadiene is very dangerous and flammable, and since there is no oxygen in the system, combustion is prevented. Liquid chlorine acts as a reactant; using liquid chlorine facilitates higher raw material conversion rates, higher product yields, and less subsequent tail gas, thus solving the problem of generating large amounts of wastewater from tail gas treatment.

[0008] By adding a mixture of 1,3-butadiene and haloalkanes dropwise into liquid chlorine, complete conversion is ensured, resulting in less chlorine in the tail gas and less wastewater in the post-treatment process. It is also safer than introducing chlorine and 1,3-butadiene into the reaction simultaneously.

[0009] Furthermore, in step (1), the mass ratio of 1,3-butadiene to haloalkanes is 1:2~5, and the temperature is maintained at 0~10℃.

[0010] At low temperatures, 1,3-butadiene dissolves in haloalkanes, ensuring the complete reaction with liquid chlorine in the next step.

[0011] Furthermore, in step (1), the mass ratio of 1,3-butadiene to haloalkanes is 1:3~3.5, and the temperature is maintained at 0~5℃.

[0012] Furthermore, in step (2), the molar ratio of liquid chlorine to 1,3-butadiene is 2~4:1.

[0013] Furthermore, in step (2), the molar ratio of liquid chlorine to 1,3-butadiene is 2.1~2.5:1.

[0014] Excess liquid chlorine ensures complete reaction, producing 1,2,3,4-tetrachlorobutane instead of intermediates such as dichlorobutane.

[0015] Controlling the dosage range of liquid chlorine and 1,3-butadiene mentioned above helps to improve the conversion rate and the purity of the product.

[0016] Furthermore, in step (2), the mixture is added over a period of 3-8 hours, and the reaction temperature is maintained at 30-40°C. During this process, the pressure of the sealed environment is adjusted to be above the saturated vapor pressure of liquid chlorine.

[0017] Maintaining the pressure of the sealed environment above the saturated vapor pressure of liquid chlorine reduces its vaporization, ensuring it exists primarily in the liquid phase. This reduces chlorine consumption while maintaining product yield. The pressure of the sealed environment can be controlled by introducing a protective gas such as nitrogen or argon, or by adjusting the volume of the sealed environment.

[0018] Furthermore, in step (2), the mixture is added over a period of 4-4.5 hours and the reaction temperature is maintained at 30-35°C. During this process, a protective gas is introduced into the sealed environment so that the pressure of the sealed environment is above the saturated vapor pressure of liquid chlorine.

[0019] By controlling the dropping time, the reaction rate and heat release of liquid chlorine and 1,3-butadiene can be controlled, side reactions can be suppressed, and the yield and purity of the target product 1,2,3,4-tetrachlorobutane can be improved.

[0020] Furthermore, the haloalkane is dichloroethane or dichloropropane.

[0021] Further, in step (2), after the reaction is completed, the product is cooled and crystallized, filtered, and a crude product is obtained. The crude product is recrystallized with ethanol to obtain 1,2,3,4-tetrachlorobutane.

[0022] Furthermore, in step (2), when liquid chlorine is introduced, the temperature of the sealed environment is 0-10℃. Low temperature is used to reduce the vaporization of liquid chlorine.

[0023] Furthermore, in step (2), after the reaction is completed, the chlorine gas in the system is purged to the tail gas absorption device with nitrogen.

[0024] The above-described technical solution of the present invention has at least the following beneficial effects: (1) The present invention uses haloalkanes as solvents, and after being mixed evenly with 1,3-butadiene, they are continuously added dropwise to liquid chlorine raw materials to carry out the reaction, which ensures the safety of the reaction. The above method improves the reaction conditions and solves the problem that the reaction is relatively dangerous because 1,3-butadiene itself is flammable and explosive.

[0025] (2) By using liquid chlorine instead of chlorine gas, it is easier to control the amount of liquid chlorine used, so that chlorine reacts completely with 1,3-butadiene, reducing the amount of chlorine used and thus reducing production costs. Moreover, it will not generate a large amount of wastewater due to the subsequent treatment of tail gas chlorine.

[0026] The entire synthesis process is environmentally safe, producing no large amounts of wastewater or chlorine gas. It also boasts high raw material conversion rates and high, stable product yields, giving it significant advantages for industrialization. Attached Figure Description

[0027] Figure 1 This is a gas chromatogram of the product from Example 1. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0029] Example 1 A method for synthesizing 1,2,3,4-tetrachlorobutane specifically includes the following steps: (1) First, purge the high-pressure enamel-lined reactor (500ml) and the mixing vessel with nitrogen; Add 162.27g of dichloroethane to a mixing vessel, start stirring, and then introduce 54.09g of 1,3-butadiene into the mixing vessel and mix evenly. Maintain the temperature at 0~5℃ to obtain a mixture. (2) Add 163.3g of liquid chlorine quantitatively to the high-pressure enamel reactor, start stirring, and cool down to 0~10℃; The mixture (216.36g) in the mixing vessel was added dropwise to the high-pressure enamel-lined reactor using a plunger pump over a period of 4.5 hours. The reaction temperature was maintained at 30-35°C. During the reaction, nitrogen gas was introduced to maintain the pressure of the high-pressure enamel-lined reactor at 1 MPa (gauge pressure). After the reaction is complete, the mixture is cooled to crystallize, then filtered through a tubular filter to obtain a crude product. Nitrogen gas is then used to purge the chlorine gas in the system into the tail gas absorption device. The crude product was recrystallized from ethanol to obtain 190.7 g of the product, with a purity of 99.13% (e.g., ...). Figure 1 As shown in the figure, the yield was 96.5%.

[0030] Example 2 A method for synthesizing 1,2,3,4-tetrachlorobutane specifically includes the following steps: (1) First, purge the high-pressure enamel-lined reactor (500ml) and the mixing vessel with nitrogen; Add 162.27g of dichloroethane to a mixing vessel, start stirring, and then introduce 54.09g of 1,3-butadiene into the mixing vessel and mix evenly. Maintain the temperature at 0~5℃ to obtain a mixture. (2) Add 149.1g of liquid chlorine quantitatively to the high-pressure enamel-lined reactor, start stirring, and cool down to 0~10℃; The mixture (216.36g) in the mixing vessel was added dropwise to the high-pressure enamel-lined reactor using a plunger pump over a period of 4 hours. The reaction temperature was maintained at 30-35℃. During the reaction, nitrogen gas was introduced to maintain the pressure of the high-pressure enamel-lined reactor at 1MPa (gauge pressure). After the reaction is complete, the mixture is cooled to crystallize, then filtered through a tubular filter to obtain a crude product. Nitrogen gas is then used to purge the chlorine gas in the system into the tail gas absorption device. The crude product was recrystallized from ethanol to obtain 189.61 g of the product, with a purity of 99.7% and a yield of 96.5%. Example 3 A method for synthesizing 1,2,3,4-tetrachlorobutane specifically includes the following steps: (1) First, use nitrogen to replace the high-pressure enamel-lined reactor (500ml) and the mixing vessel.

[0031] Add 162.27g of dichloroethane to a mixing vessel, start stirring, and then introduce 54.09g of 1,3-butadiene into the mixing vessel and mix evenly. Maintain the temperature at 0~5℃ to obtain a mixture. (2) Add 149.1g of liquid chlorine quantitatively to the high-pressure enamel-lined reactor, start stirring, and cool down to 0~10℃; The mixture (216.36g) in the mixing vessel was added dropwise to the high-pressure enamel-lined reactor using a plunger pump over a period of 4.2 hours. The reaction temperature was maintained at 30-35°C. During the reaction, nitrogen gas was introduced to maintain the pressure of the high-pressure enamel-lined reactor at 1 MPa (gauge pressure). After the reaction is complete, the mixture is cooled to crystallize, then filtered through a tubular filter to obtain a crude product. Nitrogen gas is then used to purge the chlorine gas in the system into the tail gas absorption device. The crude product was recrystallized from ethanol to obtain 188.06 g of product with a purity of 99.6% and a yield of 96%.

[0032] Example 4 A method for synthesizing 1,2,3,4-tetrachlorobutane specifically includes the following steps: (1) First, use nitrogen to replace the high-pressure enamel-lined reactor (500ml) and the mixing vessel.

[0033] Add 162.27g of dichloroethane to a mixing vessel, start stirring, and then introduce 54.09g of 1,3-butadiene into the mixing vessel and mix evenly. Maintain the temperature at 0~5℃ to obtain a mixture. (2) Add 177.5g of liquid chlorine quantitatively to the high-pressure enamel reactor, start stirring, and cool down to 0~10℃; The mixture (216.36g) in the mixing vessel was added dropwise to the high-pressure enamel-lined reactor using a plunger pump over a period of 4.5 hours. The reaction temperature was maintained at 30-35°C. During the reaction, nitrogen gas was introduced to maintain the pressure of the high-pressure enamel-lined reactor at 1 MPa (gauge pressure). After the reaction is complete, the mixture is cooled to crystallize, then filtered through a tubular filter to obtain a crude product. Nitrogen gas is then used to purge the chlorine gas in the system into the tail gas absorption device. The crude product was recrystallized from ethanol to obtain 190.59 g of product with a purity of 99.7% and a yield of 97%.

[0034] Example 5 A method for synthesizing 1,2,3,4-tetrachlorobutane specifically includes the following steps: (1) First, use nitrogen to replace the high-pressure enamel-lined reactor (500ml) and the mixing vessel.

[0035] Add 162.27g of dichloroethane to a mixing vessel, start stirring, and then introduce 54.09g of 1,3-butadiene into the mixing vessel and mix evenly. Maintain the temperature at 0~5℃ to obtain a mixture. (2) Add 177.5g of liquid chlorine quantitatively to the high-pressure enamel reactor, start stirring, and cool down to 0~10℃; The mixture (216.36g) in the mixing vessel was added dropwise to the high-pressure enamel-lined reactor using a plunger pump over a period of 4 hours. The reaction temperature was maintained at 30-35℃. During the reaction, nitrogen gas was introduced to maintain the pressure of the high-pressure enamel-lined reactor at 1MPa (gauge pressure).

[0036] After the reaction is complete, the mixture is cooled to crystallize, then filtered through a tubular filter to obtain a crude product. Nitrogen gas is then used to purge the chlorine gas in the system into the tail gas absorption device. The crude product was recrystallized from ethanol to obtain 190.59 g of product with a purity of 99.7% and a yield of 97%.

[0037] Example 6 This embodiment is basically the same as embodiment 1, except that: in step (1), the temperature is maintained at 5~10℃.

[0038] Comparative Example 1 A method for synthesizing 1,2,3,4-tetrachlorobutane specifically includes the following steps: (1) First, use nitrogen to replace the high-pressure enamel-lined reactor (500ml) and the mixing vessel.

[0039] 162.27g of dichloroethane was added to a mixing vessel, and stirring was started. Then, 54.09g of 1,3-butadiene and 220.5g of chlorine gas were metered into the mixing vessel. The reaction temperature was maintained at 30-35℃ and the pressure was maintained at 0.2MPa. After 4.5h of reaction, After the reaction is complete, the mixture is cooled to crystallize, then filtered through a tubular filter to obtain a crude product. Nitrogen gas is then used to purge the chlorine gas in the system into the tail gas absorption device. The crude product was recrystallized from ethanol to obtain 189.61 g of product with a purity of 99.7% and a yield of 96.5%.

[0040] The exhaust gas absorption device collected 43g more chlorine gas than in Example 4. All of this needs to be neutralized with 32% liquid alkali, which requires 152g more liquid alkali and 155g more wastewater.

Claims

1. A method for synthesizing 1,2,3,4-tetrachlorobutane, characterized in that, Includes the following steps: (1) Under a protective gas environment, 1,3-butadiene was mixed with haloalkanes to obtain a mixture; (2) Liquid chlorine is introduced into a sealed environment filled with protective gas, and then a mixture is added dropwise to the liquid chlorine at 30-40°C to react and obtain 1,2,3,4-tetrachlorobutane.

2. The method for synthesizing 1,2,3,4-tetrachlorobutane according to claim 1, characterized in that, In step (1), the mass ratio of 1,3-butadiene to haloalkanes is 1:2~5, and the temperature is maintained at 0~10℃.

3. The method for synthesizing 1,2,3,4-tetrachlorobutane according to claim 2, characterized in that, In step (1), the mass ratio of 1,3-butadiene to haloalkanes is 1:3~3.5, and the temperature is maintained at 0~5℃.

4. A method for synthesizing 1,2,3,4-tetrachlorobutane according to any one of claims 1-3, characterized in that, In step (2), the molar ratio of liquid chlorine to 1,3-butadiene is 2~4:

1.

5. The method for synthesizing 1,2,3,4-tetrachlorobutane according to claim 4, characterized in that, In step (2), the molar ratio of liquid chlorine to 1,3-butadiene is 2.1~2.5:

1.

6. The method for synthesizing 1,2,3,4-tetrachlorobutane according to claim 1, characterized in that, In step (2), the mixture is added over a period of 3-8 hours and the reaction temperature is maintained at 30-40°C. During this process, the pressure of the sealed environment is adjusted to be above the saturated vapor pressure of liquid chlorine.

7. The method for synthesizing 1,2,3,4-tetrachlorobutane according to claim 6, characterized in that, In step (2), the mixture is added over a period of 4-4.5 hours and the reaction temperature is maintained at 30-35°C. During this process, a protective gas is introduced into the sealed environment so that the pressure of the sealed environment is above the saturated vapor pressure of liquid chlorine.

8. The method for synthesizing 1,2,3,4-tetrachlorobutane according to claim 1, characterized in that, The haloalkane is dichloroethane or dichloropropane.

9. The method for synthesizing 1,2,3,4-tetrachlorobutane according to claim 1, characterized in that, In step (2), when liquid chlorine is introduced, the temperature of the sealed environment is 0-10℃.

10. The method for synthesizing 1,2,3,4-tetrachlorobutane according to claim 1, characterized in that, In step (2), after the reaction is complete, the mixture is cooled to crystallize, filtered, and a crude product is obtained. The crude product is recrystallized with ethanol to obtain 1,2,3,4-tetrachlorobutane.

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