Process for the continuous synthesis of 1,2-diphenylethane

Abstract

The application discloses a continuous synthesis method of 1,2-diphenyl ethane, and relates to the technical field of fine chemical industry. The synthesis method comprises the following steps: uniformly mixing raw material benzene and a catalyst, and then respectively pumping the mixture into a first reactor, a second reactor and a third reactor; pumping dichloroethane into the first reactor, and measuring the pumping flow according to a flow meter; and controlling the feeding proportion of the benzene and catalyst mixture in the first reactor, the second reactor and the third reactor, so as to inhibit the generation of side reactions, especially the generation of heavy component materials, and effectively improve the production efficiency and reduce the generation cost. The synthesis method has higher continuous reaction automation level, more accurate control over the reaction process, and more stable yield and quality of diphenyl ethane; there is only one continuous reaction tail gas discharge port, and the organic solvent can be effectively recovered, the volatilization of the organic solvent is reduced, and VOCs are more easily controlled.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of fine chemical technology, and particularly relates to a continuous synthesis method of 1,2-diphenyl ethane. BACKGROUND

[0002] Organic bromine flame retardant is one of the largest yield flame retardants, and decabromodiphenyl ethane as a new type of bromine flame retardant has the advantages of high bromine content, good flame retardant performance, low toxicity, excellent thermal and light stability, etc., and has become the main force of bromine flame retardant. Diphenyl ethane is mainly used for synthesizing decabromodiphenyl ethane. At present, the method for synthesizing diphenyl ethane is as follows: one is the coupling reaction of halogenated benzyl, as shown in formula (1).

[0003]

[0004] CN 101643384 B discloses a preparation method of high-purity 1,2-diphenyl ethane, wherein diphenyl ethane is mainly synthesized by using chlorinated benzyl, the yield of diphenyl ethane is 78%, and the content is 99%; however, the production cost is high due to the high price of halogenated benzyl, and the conversion rate is low; another is the synthesis reaction of benzene and dichloroethane by using aluminum chloride as a catalyst, and the reaction formula is as shown in formula (2). A large amount of hydrogen chloride gas is generated in the synthesis process of the method, which causes corrosion of equipment and environmental pollution, and the molar ratio of benzene and dichloroethane is high. Due to the low utilization rate of benzene, benzene needs to be recovered by distillation and then used, which causes the increase of production energy consumption and cost.

[0005]

[0006] The synthesis method of 1,2-diphenyl ethane in the above prior art is a batch production method, and the batch synthesis method has the following technical defects:

[0007] (1) The batch reaction consumes a large amount of solvent, and the operation is relatively complicated.

[0008] (2) The reaction is operated in batches, dichloroethane is added dropwise, and the rest of the materials are put into the reaction kettle at the same time, so that the reaction rate is unstable.

[0009] (3) The batch reaction uses multiple reaction kettles and multiple exhaust ports, organic solvents are easy to volatilize, VOCs control is difficult, the labor cost is high, the operation intensity is large, and the safety is not high.

[0010] That is, due to the use of the batch production method, the preparation process of the above diphenyl ethane causes the technical problems of low production cost, low conversion rate, and a large amount of hydrogen chloride gas polluting the environment.

[0011] To solve the above technical problems, CN109456138 A discloses a method for synthesizing 1,2-diphenyl ethane by using a complex ionic liquid as a catalyst, which comprises the following steps: preparing a complex ionic liquid, and then mixing the complex ionic liquid with benzene and 1,2-dichloroethane to synthesize 1,2-diphenyl ethane in a liquid phase.

[0012] The method mainly introduces the use of a complex ionic liquid as a catalyst to prepare 1,2-diphenyl ethane. According to the scheme disclosed in the embodiments of the specification, a batch production process is also used. Therefore, the production process has the above technical defects, and the use of a complex ionic liquid as a catalyst increases the difficulty of wastewater treatment.

[0013] Therefore, the prior art needs to be further improved. SUMMARY

[0014] The present application aims to provide a continuous synthesis method for 1,2-diphenyl ethane, which can realize the continuous production of diphenyl ethane by improving the process, and reduce the loss of catalyst in the synthesis method and improve the reaction yield.

[0015] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0016] A continuous synthesis method for 1,2-diphenyl ethane comprises the following steps in sequence:

[0017] a. Connect the required system

[0018] The system comprises a raw material device, a reaction device, a heat preservation device and an extraction device. The raw material device comprises a first raw material tank and a second raw material tank. The reaction device comprises a first reactor, a second reactor, a third reactor and a fourth reactor connected in sequence.

[0019] The first raw material tank is provided with a stirring mechanism, and the raw material benzene and the catalyst are mixed uniformly in the first raw material tank by the stirring mechanism.

[0020] The outlet of the first raw material tank is connected to a first outlet pipeline, and the first outlet pipeline is provided with a first branch pipeline, a second branch pipeline and a third branch pipeline. The first branch pipeline, the second branch pipeline and the third branch pipeline are connected to the first reactor, the second reactor and the third reactor, respectively.

[0021] The second raw material tank is used to store the raw material dichloroethane solution, the outlet of the second raw material tank is connected with a second outlet pipeline, and the other end of the second outlet pipeline is connected with the first reactor;

[0022] The fourth reactor is connected with a heat preservation device, and the heat preservation device is connected with an extraction device.

[0023] b. The benzene and the catalyst are uniformly mixed in the first raw material tank, the mass percentage of the catalyst is 0.015% to 0.025%, the dichloroethane solution in the second raw material tank is added into the first reactor, and the mixed solution in the first raw material tank is sent into the corresponding first reactor, second reactor and third reactor through the first branch pipeline, the second branch pipeline and the third branch pipeline respectively, wherein the flow ratio of the first reactor, the second reactor and the third reactor is 8:2:1; the reaction temperature of the first reactor is 42 to 45 DEG C, the reaction temperature of the second reactor is 45 to 48 DEG C, the reaction temperature of the third reactor is 48 to 52 DEG C, and the reaction temperature of the fourth reactor is 52 to 55 DEG C; the reaction liquid in the first reactor flows through the second reactor, the third reactor and the fourth reactor in sequence for reaction;

[0024] c. The reaction liquid obtained from the fourth reactor enters the heat preservation device, and then enters the extraction device for water washing, and after distillation concentration and rectification, the product is obtained.

[0025] As a preferred scheme of the present application, the first reactor, the second reactor, the third reactor and the fourth reactor are all provided with a stirrer.

[0026] As another preferred scheme of the present application, the molar ratio of benzene, catalyst and dichloroethane entering the first reactor is 8 to 15:0.03 to 0.08:1.

[0027] Preferably, the heat preservation device is a heat preservation tank, and the temperature of the heat preservation tank is set to 55 to 60 DEG C.

[0028] Preferably, the extraction device comprises an extraction tower, the material obtained from the heat preservation device enters the extraction tower from the middle of the extraction tower, water enters the extraction tower from the top of the extraction tower, the waste water after water washing is discharged from the bottom of the extraction tower, and the material after water washing is taken out from the top of the extraction tower.

[0029] Further, the ratio of water to the feed material of the extraction tower is 1 to 1.5:1.

[0030] Further, the distillation concentration control temperature is 90 to 100 DEG C, and the vacuum degree is -0.095 to -0.090 MPa.

[0031] Further, the rectification control temperature is 230-240 DEG C, the vacuum pressure is 0.090-0.096 MPa, and the reflux ratio is 5-10:1.

[0032] Further, the catalyst is aluminum trichloride.

[0033] Further, adjusting valves and flow meters are arranged on the first branch pipeline, the second branch pipeline, the third branch pipeline and the second outlet pipeline; and pumps are arranged on the first outlet pipeline, the second outlet pipeline and the pipeline connecting the heat preservation device and the extraction device.

[0034] Compared with the prior art, the present application has the following beneficial technical effects:

[0035] The present application provides a continuous synthesis method of 1,2-diphenylethane, which realizes the continuous production of 1,2-diphenylethane by combining the system used, after the raw material benzene and the catalyst are uniformly mixed, they are pumped into the first reactor, the second reactor and the third reactor respectively, dichloroethane is pumped into the first reactor, the pumping flow is measured according to the flow meter, by controlling the feeding ratio of the benzene and catalyst mixture in the first reactor, the second reactor and the third reactor, the generation of side reactions can be inhibited, especially the generation of heavy component materials, the production efficiency can be effectively improved, and the generation cost can be reduced.

[0036] The method has higher continuous reaction automation level, more accurate control of the reaction process, and more stable diphenylmethane yield and quality.

[0037] The continuous reaction has only one tail gas discharge port, can effectively recover the organic solvent, reduces the volatilization of the organic solvent, and the VOCs are easier to control. There is no auxiliary time problem in intermittent operation, good stability in large-scale production, safe operation, simple automatic operation, and saving of manpower. BRIEF DESCRIPTION OF DRAWINGS

[0038] The present application will be further described below in combination with the drawings:

[0039] Figure 1 The present application provides a continuous synthesis method of 1,2-diphenylethane, which realizes the continuous production of 1,2-diphenylethane by combining the system used, after the raw material benzene and the catalyst are uniformly mixed, they are pumped into the first reactor, the second reactor and the third reactor respectively, dichloroethane is pumped into the first reactor, the pumping flow is measured according to the flow meter, by controlling the feeding ratio of the benzene and catalyst mixture in the first reactor, the second reactor and the third reactor, the generation of side reactions can be inhibited, especially the generation of heavy component materials, the production efficiency can be effectively improved, and the generation cost can be reduced.

[0040] In the figure:

[0041] 1, first raw material tank, 2, second raw material tank, 3, first reactor, 4, second reactor, 5, third reactor, 6, fourth reactor, 7, heat preservation tank, 8, extraction column. DETAILED DESCRIPTION

[0042] The application provides a continuous synthesis method of 1,2-diphenylethane.

[0043] The raw materials mentioned in the application can be purchased through a commercial channel.

[0044] The continuous synthesis method of 1,2-diphenylethane can be realized by combining a continuous production system with a process, the continuous synthesis process is adopted, so that the tail gas discharge port is less, the volatilization of the organic solvent is reduced, and the production efficiency is improved.

[0045] As shown in the figure, the application provides a continuous synthesis method of 1,2-diphenylethane, which comprises the following steps in sequence: Figure 1

[0046] Step one, connecting the required system

[0047] The system comprises a raw material device, a reaction device, a heat preservation device and an extraction device, the raw material device comprises a first raw material tank 1 and a second raw material tank 2, the reaction device comprises a first reactor 3, a second reactor 4, a third reactor 5 and a fourth reactor 6 which are connected in sequence;

[0048] The first raw material tank is provided with a stirring mechanism, the stirring mechanism comprises a motor and a stirring paddle, the motor drives the stirring paddle to rotate, and stirring paddle blades are arranged on the stirring paddle, so that the raw material benzene and the catalyst are uniformly mixed in the first raw material tank through the stirring mechanism;

[0049] The outlet of the first raw material tank is connected with a first outlet pipeline, a pump is arranged on the first outlet pipeline, the raw material in the first raw material tank is pumped into the corresponding reactor, a first branch pipeline, a second branch pipeline and a third branch pipeline are arranged on the outlet pipeline, and the first branch pipeline, the second branch pipeline and the third branch pipeline are connected with the first reactor, the second reactor and the third reactor respectively; flow meters and adjusting valves are arranged on the first branch pipeline, the second branch pipeline and the third branch pipeline, and the flow meters and the adjusting valves are used to control the entry of the raw material liquid.

[0050] In order to ensure the continuous synthesis of diphenylethane, the flow ratio of the raw material liquid in the first raw material tank in the first reactor, the second reactor and the third reactor is 8:2:1.

[0051] The second raw material tank is arranged with a raw material dichloroethane solution, the outlet of the second raw material tank is connected with a second outlet pipeline, and the other end of the second outlet pipeline is connected with the first reactor;

[0052] ​The fourth reactor is connected with a heat preservation device, such as a heat preservation tank, the temperature of the heat preservation tank 7 is set to 55-60℃, the material liquid after heat preservation enters an extraction device, the extraction device is an extraction tower 8, the material liquid enters from the middle of the extraction tower 8, water enters from the top of the extraction tower, the waste water after water washing is discharged from the bottom of the extraction tower, and the material after water washing is collected from the top of the extraction tower;

[0053] Step two, the benzene and catalyst are uniformly mixed in the first raw material tank, the mass percentage of the catalyst is 0.015%-0.025%, the dichloroethane solution in the second raw material tank is added to the first reactor, and the mixed liquid in the first raw material tank is sent into the corresponding first reactor, second reactor and third reactor through the first branch pipeline, second branch pipeline and third branch pipeline respectively, the reaction temperature of the first reactor is 42-45℃, the reaction temperature of the second reactor is 45-48℃, the reaction temperature of the third reactor is 48-52℃, and the reaction temperature of the fourth reactor is 52-55℃; the reaction liquid in the first reactor flows through the second reactor, third reactor and fourth reactor in turn for reaction;

[0054] Step three, the reaction liquid obtained from the fourth reactor enters the heat preservation tank, then enters the extraction tower for water washing, and then is concentrated and rectified by distillation to obtain the product.

[0055] The application is further described below in combination with specific examples.

[0056] Example 1:

[0057] The benzene and catalyst trichloride aluminum mixed liquid, dichloroethane solution are mixed according to the molar ratio of 10:0.05:1, the benzene and trichloride aluminum mixed liquid are pumped into the first reactor, second reactor and third reactor according to the flow ratio of 8:2:1, the dichloroethane solution is pumped into the first reactor, the reaction temperature of the first reactor is 42℃, the reaction temperature of the second reactor is 45℃, the reaction temperature of the third reactor is 48℃, then it enters the fourth reactor, the reaction temperature of the fourth reactor is 52℃, after reaction, it enters the heat preservation tank, the temperature in the heat preservation tank is controlled at 55℃ for 5h, after reaction, the material liquid is pumped into the extraction tower for continuous extraction, the upper liquid after extraction is continuously collected, the system is continuously operated for 24h, the material after water washing is concentrated by vacuum distillation, the temperature is controlled at 90-95℃, the crude diphenyl ethane is obtained, the concentrated material is rectified, the vacuum degree is-0.095MPa, the bottom temperature is controlled at 230-240℃, the diphenyl ethane product is obtained, the total yield is 90.1%, and the product content is 99.95%.

[0058] Example 2:

[0059] benzene and catalyst aluminum trichloride mixture, dichloroethane solution according to the molar ratio of 10:0.05:1, the benzene and aluminum trichloride mixture is pumped into the first reactor, the second reactor and the third reactor according to the flow ratio of 8:2:1, the dichloroethane solution is pumped into the first reactor, the reaction temperature of the first reactor is 45℃, the reaction temperature of the second reactor is 48℃, the reaction temperature of the third reactor is 52℃, then into the fourth reactor, the reaction temperature of the fourth reactor is 55℃, after the reaction, into the heat preservation tank, the temperature in the heat preservation tank is controlled at 60℃ for 5h, after the reaction is finished, the material liquid is pumped into the extraction tower for continuous extraction, the upper liquid after extraction is continuously extracted, the system is continuously operated for 24h, after the upper layer is washed, the material is concentrated by vacuum distillation, the temperature is controlled at 90-95℃, the crude diphenyl ethane is obtained, the concentrated material is rectified, the vacuum degree is-0.095MPa, the bottom temperature is controlled at 230-240℃, the diphenyl ethane product is obtained, the total yield is 90.7%, the product content is 99.90%.

[0060] Example 3:

[0061] benzene and catalyst aluminum trichloride mixture, dichloroethane solution according to the molar ratio of 15:0.06:1, the benzene and aluminum trichloride mixture is pumped into the first reactor, the second reactor and the third reactor according to the flow ratio of 8:2:1, the dichloroethane solution is pumped into the first reactor, the reaction temperature of the first reactor is 43℃, the reaction temperature of the second reactor is 46℃, the reaction temperature of the third reactor is 50℃, then into the fourth reactor, the reaction temperature of the fourth reactor is 53℃, after the reaction, into the heat preservation tank, the temperature in the heat preservation tank is controlled at 55℃ for 5h, after the reaction is finished, the material liquid is pumped into the extraction tower for continuous extraction, the upper liquid after extraction is continuously extracted, the system is continuously operated for 24h, after the upper layer is washed, the material is concentrated by vacuum distillation, the temperature is controlled at 90-95℃, the crude diphenyl ethane is obtained, the concentrated material is rectified, the vacuum degree is-0.095MPa, the bottom temperature is controlled at 230-240℃, the diphenyl ethane product is obtained, the total yield is 90.9%, the product content is 99.4%.

[0062] Comparative Example 1:

[0063] The difference between the embodiment 1 and the embodiment 4 is that the benzene and the aluminum trichloride mixed solution is added into the reaction kettle, a certain amount of dichloroethane is added into the reaction kettle by dropwise adding, the molar ratio of benzene: aluminum trichloride: dichloroethane is 13.3:0.11:1, the reaction temperature is controlled at 40-50 DEG C, the dropwise adding time is 3-4 h, after the dropwise adding is completed, the temperature is increased to 60-65 DEG C and is kept for 5 h, after the organic layer is washed for 3 times by using the process water, the organic layer is concentrated by distillation under reduced pressure, the temperature is controlled at 90-95 DEG C, the crude diphenyl ethane is obtained, the concentrated material is rectified, the vacuum degree is-0.095 MPa, the bottom temperature is controlled at 230-240 DEG C, the diphenyl ethane product is obtained, and the total yield is 82%, and the product content is 99.1%.

[0064] The above embodiment 1-embodiment 3 is a schematic description of the present application, and is not limited. Under the guidance of the above embodiment 1-embodiment 3, different embodiment combinations can also be obviously obtained by those skilled in the art.

[0065] The part not described in the present application can be realized by referring to the prior art.

[0066] It should be noted that any equivalent manner or obvious variation manner made by those skilled in the art under the teaching of the present application should be within the protection scope of the present application.

Claims

1. A method for the continuous synthesis of 1,2-diphenylethane, characterized in that, The following steps are included in sequence: a. Connect the required systems The system includes a raw material device, a reaction device, a heat preservation device and an extraction device. The raw material device includes a first raw material tank and a second raw material tank. The reaction device includes a primary reactor, a secondary reactor, a tertiary reactor and a quaternary reactor connected in sequence. The first raw material tank is provided with raw material benzene and catalyst, and the first raw material tank is equipped with a stirring mechanism, and the raw material benzene and catalyst are mixed uniformly in the first raw material tank through the stirring mechanism; The outlet of the first raw material tank is connected to the first outlet pipeline, and the first branch pipeline, the second branch pipeline and the third branch pipeline are provided on the first outlet pipeline, and the first branch pipeline, the second branch pipeline and the third branch pipeline are connected to the primary reactor, the secondary reactor and the tertiary reactor respectively; The raw material dichloroethane solution is placed in the second raw material tank, the outlet of the second raw material tank is connected to the second outlet pipeline, and the other end of the second outlet pipeline is connected to the primary reactor; The four-stage reactor is connected to the heat preservation device, and the heat preservation device is connected to the extraction device; b. Mixing benzene and the catalyst uniformly in a first raw material tank, wherein the mass percentage of the catalyst is 0.015% to 0.025%, adding the dichloroethane solution in the second raw material tank to the primary reactor, and respectively sending the mixed solution obtained in the first raw material tank to the corresponding primary reactor, secondary reactor, and tertiary reactor through the first branch pipeline, the second branch pipeline, and the third branch pipeline, wherein the flow ratio of the primary reactor, the secondary reactor, and the tertiary reactor is 8:2:1; the reaction temperature of the primary reactor is 42 to 45° C., the reaction temperature of the secondary reactor is 45 to 48° C., the reaction temperature of the tertiary reactor is 48 to 52° C., and the reaction temperature of the quaternary reactor is 52 to 55° C.; the reaction solution in the primary reactor flows through the secondary reactor, the tertiary reactor, and the quaternary reactor in sequence to react; c. The reaction liquid obtained from the four-stage reactor enters the insulation device, and then enters the extraction device from the insulation device for water washing, and then is concentrated and rectified by distillation to obtain; The catalyst is aluminum trichloride, and the molar ratio of benzene, the catalyst and dichloroethane is 8-15:0.03-0.08:

1.

2. The process for the continuous synthesis of 1,2-diphenylethane according to claim 1, characterized in that: The first-stage reactor, the second-stage reactor, the third-stage reactor and the fourth-stage reactor are all equipped with a stirrer.

3. The process for the continuous synthesis of 1,2-diphenylethane according to claim 1, characterized in that: The heat preservation device is a heat preservation tank, and the temperature of the heat preservation tank is set at 55-60°C.

4. The process for the continuous synthesis of 1,2-diphenylethane according to claim 1, characterized in that: The extraction device includes an extraction tower. The material obtained from the insulation device enters the extraction tower from the middle of the extraction tower, water enters the extraction tower from the top of the extraction tower, the waste water after water washing is discharged from the bottom of the extraction tower, and the washed material is extracted from the top of the extraction tower.

5. The process for the continuous synthesis of 1,2-diphenylethane according to claim 4, characterized in that: The ratio of water to the feed material of the extraction column is 1 to 1.5:

1.

6. The process for continuous synthesis of 1,2-diphenylethane according to claim 1, characterized in that: The distillation concentration temperature is controlled at 90-100°C, and the vacuum degree is -0.095 to -0.090 MPa.

7. The process for the continuous synthesis of 1,2-diphenylethane according to claim 1, characterized in that: The distillation control temperature is 230-240°C, the vacuum pressure is 0.090-0.096 MPa, and the reflux ratio is 5-10:

1.

8. The process for the continuous synthesis of 1,2-diphenylethane according to claim 1, characterized in that: Adjusting valves and flow meters are arranged on the first branch pipeline, the second branch pipeline, the third branch pipeline and the second outlet pipeline; pumps are arranged on the first outlet pipeline, the second outlet pipeline and the pipeline connecting the heat preservation device and the extraction device.

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