A method for continuously producing 4-chlorobenzenesulfonic acid

Abstract

The application discloses a method for continuously preparing 4-chlorobenzenesulfonic acid, and the 4-chlorobenzenesulfonic acid is prepared through a continuous equipment, and the specific steps are as follows: step one, sulfur trioxide is dissolved in chloroform to prepare a 20% sulfur trioxide solution; step two, the 20% sulfur trioxide solution is mixed with benzene chloride with a mass concentration of 99% to obtain a mixed solution; and step three, the 4-chlorobenzenesulfonic acid is prepared through temperature control and stirring reaction of the mixed solution in an n-stage continuous reaction equipment. The application has the following beneficial effects: through directional selection of the halogenated hydrocarbon as chloroform and through the continuous reaction device, the conversion rate of the benzene chloride in the application is about 99%, and the molar yield of the 4-chlorobenzenesulfonic acid product can reach more than 92% compared with the selection of other halogenated hydrocarbons.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of organic synthesis, and particularly relates to a method for continuously preparing 4-chlorobenzenesulfonic acid. BACKGROUND

[0002] 4-chlorobenzenesulfonic acid is p-chlorobenzenesulfonyl chloride, which is an important organic synthesis intermediate and is widely used in the dye, pharmaceutical and other industries. It is also an important raw material for synthesizing chemical intermediate 4,4'-dichlorodiphenyl sulfone. P-chlorobenzenesulfonic acid is a light yellow needle-like crystal at room temperature, has a pungent odor, is hygroscopic, dissolves in water, slightly dissolves in ethanol, and is insoluble in chlorobenzene.

[0003] At present, the industrial production of 4-chlorobenzenesulfonic acid is mostly carried out in a batch mode. The production process involves more human participation, and each batch of reaction needs repeated feeding, reaction and discharging, which is prone to errors in operation and cannot be well controlled, resulting in high production cost.

[0004] In summary, the existing batch production method has the following defects: 1) manual feeding in the production process, low efficiency; 2) low yield.

[0005] Therefore, there is an urgent need to provide a method for continuously preparing 4-chlorobenzenesulfonic acid to solve the above problems. SUMMARY

[0006] The technical problem to be solved by the present application is:

[0007] A method for continuously preparing 4-chlorobenzenesulfonic acid is developed, which has the characteristics of efficiency improvement and high yield.

[0008] The purpose of the present application is to solve the problems existing in the prior art, and to provide a method for continuously preparing 4-chlorobenzenesulfonic acid.

[0009] In order to achieve the above purpose, the following technical scheme is adopted in the present application:

[0010] A method for continuously preparing 4-chlorobenzenesulfonic acid, which is prepared by a continuous equipment, and the specific steps are as follows:

[0011] Step one

[0012] Dissolve sulfur trioxide in halogenated hydrocarbon to prepare a 20% sulfur trioxide solution;

[0013] Step two

[0014] Mix 10% to 99% sulfur trioxide solution with 99% mass concentration benzyl chloride to obtain a mixed solution;

[0015] Step three

[0016] The 4-chlorobenzenesulfonic acid is prepared by mixing and stirring reaction of the solution in the n-stage continuous reaction equipment.

[0017] As a further improvement of the present solution,

[0018] The continuous reaction equipment comprises a mixing pump (10), a circulating pump (20), a residence kettle (30), and a discharge pump (40) arranged in sequence.

[0019] The chlorinated benzene is delivered to the mixing pump (10) and the first sulfonated residence kettle (31) through pipelines.

[0020] The sulfur trioxide solution is delivered to the mixing pump (10) and the first sulfonated residence kettle (31) through pipelines.

[0021] The mixing pump is provided with a pipeline connected to the first sulfonated residence kettle (31).

[0022] The circulating pump (20) is provided with a pipeline returning to the mixing pump.

[0023] The bottom of the first sulfonated residence kettle (31) is provided with a pipeline returning to the circulating pump (20).

[0024] The sulfonated residence kettle (30) further comprises a plurality of kettle bodies connected in series, and the last kettle body is connected to the discharge pump (40).

[0025] As a further improvement of the present solution,

[0026] The sulfonated residence kettle (30) further comprises at least the first sulfonated residence kettle (31), the second sulfonated residence kettle (32), the third sulfonated residence kettle (33), and the fourth sulfonated residence kettle (34).

[0027] Further, the sulfonated residence kettle (30) is provided with a stirring paddle.

[0028] As a further improvement of the present solution, the step 3 further comprises:

[0029] S31 The sulfur trioxide solution and the chlorinated benzene with a mass concentration of 99% are delivered to the mixing pump and mixed and reacted in the mixing pump.

[0030] S32 The reaction solution in the first sulfonated residence kettle (31) is stirred and reacted from the top inlet of the first sulfonated residence kettle (31). Meanwhile, the reaction solution in the first sulfonated residence kettle (31) is divided into two paths, one of which is returned to the mixing pump (10) through the circulating pump (20) to perform repeated sulfonation reaction, and the other of which is continuously fed from the second sulfonated residence kettle (32) to the fourth sulfonated residence kettle (34) through the third sulfonated residence kettle (33) in sequence.

[0031] S33 the reaction liquid in the fourth stage sulfonated residence kettle (34) is pumped out by a discharge pump (40) and then is recrystallized by a water solvent, centrifuged and dried to obtain 4-chlorobenzenesulfonic acid product;

[0032] The temperature of the reaction is controlled at about 15-20 DEG C, and the total residence time of the reaction liquid in the four stages of sulfonated residence kettles connected in series is about 2h.

[0033] As a further improvement of the present solution, the mass ratio of the sulfur trioxide, the halogenated hydrocarbon and the chlorinated benzene is 1:0-5:0.7-1.7.

[0034] As a further improvement of the present solution, the mass ratio of the sulfur trioxide, the halogenated hydrocarbon and the chlorinated benzene is 1:3:1.5.

[0035] As a further improvement of the present solution, the auxiliary agent for crystallization is any one or more of water, ethanol and isopropanol.

[0036] As a further improvement of the present solution, the n is an integer of 2-8.

[0037] As a further improvement of the present solution, the n is an integer of 2-8.

[0038] Compared with the prior art, the present solution has the following advantages:

[0039] 1) The method of the present solution can realize continuous industrial production of 4-chlorobenzenesulfonic acid, the sulfur trioxide solution and the chlorinated benzene are firstly forced to mix in a mixing pump to accelerate the reaction speed;

[0040] 2) Furthermore, the reaction liquid from the mixing pump is flowed into n stages of sulfonated residence kettles connected in series for stirring, and the reaction liquid in the first stage of sulfonated residence kettles is partially refluxed into the mixing pump for continuous reaction, which has the following two advantages, 1) the n stages of sulfonated residence kettles connected in series increase the reaction time to make the sulfonation reaction more thorough; 2) the generated large amount of heat can be easily removed to avoid overheat of the reaction temperature and improve the safety of the reaction;

[0041] 3) The present solution introduces more control instruments and adopts DCS control to realize industrial production of 4-chlorobenzenesulfonic acid, reduces the manual operation, and the raw material input ratio, the raw material input amount and the reaction time can be accurately controlled, so that the industrial production process is safer and more reliable;

[0042] 4) In the present solution, the halogenated hydrocarbon is selected as trichloromethane, and through the continuous reaction device, the conversion rate of the chlorinated benzene is about 99% and the molar yield of the 4-chlorobenzenesulfonic acid product can reach more than 92% compared with other halogenated hydrocarbons. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 Structure diagram of continuous production equipment for 4-chlorobenzenesulfonic acid. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described below in combination with examples:

[0045] Example 1

[0046] The structure diagram of the reaction device for continuously producing 4-chlorobenzenesulfonic acid in this example 1 is shown in Fig. 1. Figure 1 As can be seen from Fig. 1, the reaction device comprises four sulfonation residence tanks, a mixing pump, a circulating pump and a discharge pump which are connected in series. Figure 1 The outlet of the mixing pump is connected to the top inlet of the first sulfonation residence tank 1 by a pipeline, the bottom outlet of the first sulfonation residence tank 1 is connected to the inlet of the mixing pump by a pipeline through the circulating pump, forming a partial internal circulation of the reaction liquid. The middle outlet of the first sulfonation residence tank 1 is connected to the top inlet of the second sulfonation residence tank 2 by a pipeline, the middle outlet of the second sulfonation residence tank 2 is connected to the top inlet of the third sulfonation residence tank 3 by a pipeline, and the middle outlet of the third sulfonation residence tank 3 is connected to the top inlet of the fourth sulfonation residence tank 4 by a pipeline, thereby forming four sulfonation residence tanks connected in series, and control valves are arranged on the corresponding pipelines.

[0047] Sulfur trioxide was dissolved in chloroform to prepare a 20% sulfur trioxide solution for use;

[0048] The sulfur trioxide solution and benzene chloride with a mass concentration of 99% were transported into the mixing pump and mixed after reaction (the mass ratio of sulfur trioxide, chloroform and benzene chloride was 1:4:1.5), and then flowed into the first sulfonation residence tank 1 from the top inlet of the first sulfonation residence tank 1 for stirring reaction. At the same time, the reaction liquid in the first sulfonation residence tank 1 flowed out in two ways, one of which returned to the mixing pump through the circulating pump for repeated sulfonation reaction, and the other flowed from the second sulfonation residence tank 2 to the fourth sulfonation residence tank in a continuous feeding manner. The reaction liquid in the fourth sulfonation residence tank was pumped out by the discharge pump and then recrystallized with water solvent, centrifuged and dried to produce 4-chlorobenzenesulfonic acid product. The reaction temperature was controlled at about 15-20°C, and the total residence time of the reaction liquid in the mixing pump and the four sulfonation residence tanks connected in series was about 2h.

[0049] Using the above production process, when the reaction was substantially complete (i.e. the conversion rate of benzene chloride reached more than 99%), 4-chlorobenzene The molar yield of the sulfonic acid product can reach more than 92% The quality indicators of the finally produced 4-chlorobenzenesulfonic acid product are as follows : 4-chlorobenzenesulfonic acid mass fraction ≥ 99% .

[0050] Example 2:

[0051] The structure of the reaction device for continuous production of 4-chlorobenzenesulfonic acid in this Example 2 is shown in Figure 1 It can be seen from Figure 1 that the reaction device comprises four sulfonation residence tanks connected in series, a mixing pump, a circulating pump and a discharge pump. The outlet of the mixing pump is connected by a pipeline to the top inlet of the first sulfonation residence tank 1, and the bottom outlet of the first sulfonation residence tank 1 is connected by a pipeline to the inlet of the mixing pump through the circulating pump, forming a partial internal circulation of the reaction liquid. The middle outlet of the first sulfonation residence tank 1 is connected by a pipeline to the top inlet of the second sulfonation residence tank 2, the middle outlet of the second sulfonation residence tank 2 is connected by a pipeline to the top inlet of the third sulfonation residence tank 3, and the middle outlet of the third sulfonation residence tank 3 is connected by a pipeline to the top inlet of the fourth sulfonation residence tank 4, thereby forming four sulfonation residence tanks connected in series, and control valves are arranged on the corresponding pipelines;

[0052] Sulfur trioxide was dissolved in chloroform to prepare a 25% sulfur trioxide solution for use;

[0053] The sulfur trioxide solution and benzene chloride with a mass concentration of 99% were transported into the mixing pump and mixed after reaction by the mixing pump (the mass ratio of sulfur trioxide, chloroform and benzene chloride was 1:3:1.6), and then flowed into the first sulfonation residence tank 1 from the top inlet of the first sulfonation residence tank 1 for stirring reaction. At the same time, the reaction liquid in the first sulfonation residence tank 1 flowed out in two ways, one of which returned to the mixing pump through the circulating pump for repeated sulfonation reaction, and the other flowed from the second sulfonation residence tank 2 to the fourth sulfonation residence tank in a continuous feeding manner. The reaction liquid in the fourth sulfonation residence tank was pumped out by the discharge pump, and then recrystallized with an aqueous solvent, centrifuged and dried to produce 4-chlorobenzenesulfonic acid product. The reaction temperature was controlled at about 15-20°C, and the total residence time of the reaction liquid in the four sulfonation residence tanks connected in series was about 2h.

[0054] Using the above production process, the conversion rate of benzene chloride was about 99%, and the molar yield of 4-chlorobenzenesulfonic acid product could reach about 90%.

[0055] Comparative Example 1:

[0056] The example provides a preparation method of 4-chlorobenzenesulfonic acid, which is basically identical with the steps in the example 1, except that: the mixing pump and the circulating pump are not started; the sulfur trioxide solution and the benzene chloride with a mass concentration of 99% flow into the first stage sulfonation residence kettle 1 from the top inlet of the first stage sulfonation residence kettle 1 for stirring reaction; and the reaction liquid in the fourth stage sulfonation residence kettle flows to the fourth stage sulfonation residence kettle in a continuous feeding mode, and the reaction liquid in the fourth stage sulfonation residence kettle is pumped out through the discharge pump, and then is recrystallized by a water solvent, centrifuged and dried to obtain the 4-chlorobenzenesulfonic acid product; and the total residence time of the reaction liquid in the sulfonation residence kettles connected in sequence is about 6 h.

[0057] By using the above production process, the conversion rate of the benzene chloride is about 96%, and the molar yield of the 4-chlorobenzenesulfonic acid product can reach about 80%.

[0058] It can be seen from the reaction results of the comparative example 1 and the comparative example 1 that the method of the present application can be used for continuous preparation of 4-chlorobenzenesulfonic acid, and good reaction effect can be obtained. Moreover, compared with the comparative example 1, the method of the example 1 obtains better reaction effect, and greatly shortens the reaction time, which may be because the mixing pump can effectively strengthen the sulfonation reaction process when the reaction device of the example 1 is used for continuous preparation of 4-chlorobenzenesulfonic acid, and the residence time of the reaction liquid in the mixing pump is short, the reaction liquid after forced mixing by the mixing pump flows into the sulfonation residence kettle, and a large amount of heat generated in the reaction can be easily removed, so that the reaction temperature is prevented from being overheated.

[0059] Comparative example 2:

[0060] The example provides a preparation method of 4-chlorobenzenesulfonic acid, which is basically identical with the steps in the example 2, except that: the trichloromethane is replaced by trichloroethane.

[0061] By using the above production process, the conversion rate of the benzene chloride is about 96%, and the molar yield of the 4-chlorobenzenesulfonic acid product can reach about 80%.

[0062] The above only describes the preferred embodiments of the present application, and does not limit the patent scope of the present application, and any equivalent transformation made by using the present application is within the patent protection scope of the present application.

Claims

1. A method for continuous preparation of 4-chlorobenzenesulfonic acid, characterized in that, The specific steps for preparing 4-chlorobenzenesulfonic acid using a continuous process are as follows: Step 1 involves dissolving sulfur trioxide in a haloalkanes to prepare a sulfur trioxide solution with a concentration of 10% to 99%. Step 2: Mix a 10%–99% sulfur trioxide solution with a 99% chlorobenzene solution to obtain a mixed solution; Step 3 involves reacting the mixture in a 4-stage continuous reaction apparatus under controlled temperature and stirring to obtain 4-chlorobenzenesulfonic acid. Step 3 also includes: S31 sulfur trioxide solution and chlorobenzene with a mass concentration of 99% are fed into a mixing pump and mixed and reacted. S32 flows into the first sulfonation residence tank (31) from the top inlet and is stirred to react. At the same time, the reaction liquid in the first sulfonation residence tank (31) is divided into two streams. One stream is returned to the mixing pump (10) through the circulation pump (20) for repeated sulfonation reaction. The other stream is fed continuously from the second sulfonation residence tank (32) through the third sulfonation residence tank (33) and then flows to the fourth sulfonation residence tank (34). The reaction liquid in the fourth-stage sulfonation residence vessel (34) of S33 is pumped out by the discharge pump (40), and then recrystallized with water solvent, centrifuged and dried to obtain 4-chlorobenzenesulfonic acid product; The reaction temperature is controlled at around 15-20℃, and the total residence time of the reaction solution in the sulfonation residence kettle with 4 stages connected in series is about 2 hours. The mass ratio of sulfur trioxide, halogenated hydrocarbons and chlorobenzene is 1:3:1.

5. The halohydrocarbon is trichloromethane; The continuous reaction equipment includes a mixing pump (10), a circulating pump (20), a sulfonation residence tank (30), and a discharge pump (40) arranged in sequence; Chlorobenzene is transported to the mixing pump (10) and the sulfonation residence tank (31) through pipelines respectively; Sulfur trioxide solution is delivered to the mixing pump (10) and the sulfonation residence tank (31) through pipelines respectively; The mixing pump is equipped with a pipeline connecting to the sulfonation residence vessel (31); The circulating pump (20) is equipped with a pipeline for returning to the mixing pump; The bottom of the sulfonation residence vessel (31) is provided with a pipeline for reflux to the circulation pump (20); The sulfonation residence tank (30) also includes several tanks connected in series, with the end tank connected to the discharge pump (40); The sulfonation residence vessel (30) also includes sulfonation residence vessel one (31), sulfonation residence vessel two (32), sulfonation residence vessel three (33), and sulfonation residence vessel four (34), and the sulfonation residence vessel (30) is equipped with a stirring paddle.

2. The method for continuous preparation of 4-chlorobenzenesulfonic acid according to claim 1, characterized in that, The crystallization aids are any one or more of water, ethanol, and isopropanol.

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