CN211921383U

CN211921383U - 3, 4-dichloronitrobenzene integrated full-continuous flow reaction system

Info

Publication number: CN211921383U
Application number: CN201922432218.5U
Authority: CN
Inventors: 舒鑫琳; 李建敏; 吴政杰
Original assignee: Zhejiang Benli Technology Co ltd
Current assignee: Zhejiang Benli Technology Co ltd
Priority date: 2019-12-30
Filing date: 2019-12-30
Publication date: 2020-11-13
Anticipated expiration: 2029-12-30

Abstract

The utility model discloses a 3, 4-dichloronitrobenzene's full continuous flow reaction system, this reaction system can realize 3, 4-dichloronitrobenzene's full continuous flow synthesis technology down. The integrated full-continuous flow reaction system adopts a unitized structure and comprises a nitrification unit and a post-treatment unit, wherein the units are connected in series; each unit comprises at least one temperature zone, and the temperature zones are mutually connected in series; each temperature zone comprises at least one reactor module or reactor module group, wherein the reactor module group is formed by connecting a plurality of reactor modules in series or in parallel; the reactor module comprises at least one reactor. The full continuous flow synthesis of the 3, 4-dichloronitrobenzene is carried out in the integrated full continuous flow reaction system, the production time is shortened to be within 120 seconds, no amplification effect exists, the product index is stable, and the reproducibility is good.

Description

3, 4-dichloronitrobenzene integrated full-continuous flow reaction system

Technical Field

The utility model belongs to the chemical field especially relates to a continuous flow nitration production device of 3, 4-dichloronitrobenzene.

Background

The 3, 4-dichloronitrobenzene is an intermediate of various dyes, pigments, medicines and fine chemical products, and is an intermediate for synthesizing 3-chloro-4-fluoroaniline, 2, 4-dichlorofluorobenzene, 3, 4-dichloroaniline and the like. Wherein, the 3-chloro-4-fluoroaniline and the 2, 4-dichlorofluorobenzene are raw materials for preparing quinolone antibacterial drugs, and the drugs are widely used in the field of Chinese medicine. The quinolone antibiotics have the advantages of wide bactericidal spectrum, small toxic and side effects and moderate price, and are antibiotics which are developed rapidly in recent years. The developed and mass-produced quinolone antibiotics in China mainly comprise norfloxacin, ciprofloxacin, ofloxacin and the like, and account for about 98 percent of the total yield of the quinolone antibiotics in China.

Quinolones are generally obtained by synthesizing fluorine-containing quinoline compounds from fluorine-containing benzene rings and condensing with piperazine (or methylpiperazine). China is one of the countries with the largest capacity of fluorine-containing medicines and intermediates in the world, and more than 80 percent of fluorine-containing intermediates are supplied and exported. The development of the benzotrifluoride intermediate is late, the development is rapid in recent years, and the synthesis technology of the fluorine-containing pyridine intermediate becomes one of the main directions for developing the fluorine-containing intermediate in China in the next few years.

The existing process for synthesizing 3, 4-dichloronitrobenzene mainly has two routes.

Item 1 is p-chloronitrobenzene chlorination. Introducing chlorine into p-chloronitrobenzene in a molten state at 105 ℃ by taking anhydrous ferric trichloride as a catalyst to obtain the 3, 4-dichloronitrobenzene. The method has high requirements on the process and equipment, the appearance and the internal quality of the product are difficult to control, and a large amount of waste liquid generated in the reaction seriously pollutes the environment. Chlorine is a common chlorinating agent for such reactions, but NO is due to electron-withdrawing groups on the benzene ring₂The existing method has the disadvantages of harsh requirements on reaction conditions, increased side reactions, complicated operation and low reaction yield. In addition, chlorous acid has also been reported in the literature as a chlorinating agent for such aromatic compounds.

And the 2 nd stripe is to nitrify the o-dichlorobenzene to obtain the 3, 4-dichloronitrobenzene. The nitration reaction of aromatic hydrocarbon has three isomers, and the composition proportion of the three isomers is different with the difference of substituent groups on aromatic ring and the change of process conditions. For the nitration reaction using o-dichlorobenzene as raw material, the product only contains 2, 3-dichloronitrobenzene and 3, 4-dichloronitrobenzene due to special position of substituent group, the process is simple, but a large amount of isomer 2, 3-dichloronitrobenzene is produced in the nitration process, and the subsequent purification and separation are needed.

However, no matter which process route is adopted for synthesis, the prior art for producing the 3, 4-dichloronitrobenzene basically adopts an intermittent kettle type reaction, auxiliary operations such as loading and unloading are required in the intermittent production process, the labor intensity is high, the loss of materials and energy is easy to cause, the production cost is high, the production period is prolonged, the product has batch difference and unstable quality, and the kettle type process safety is difficult to ensure due to nitration reaction.

The most important features of a batch process are two-fold, one is the presence of "stops" or "interruptions" in the process, and the other is that the production of products is spaced apart, i.e., there are batches of product and only a fixed amount of product is available for a batch. That is, for each batch of production, a fixed number of starting materials are reacted in the order of reaction steps to ultimately yield a limited fixed number of products (products); then, a fixed amount of raw materials are put in, and the next batch of reaction is carried out according to the same steps to prepare a limited fixed product.

There are two ways to implement a batch process: 1) respectively using a plurality of reactors (such as flasks, reaction kettles and the like), wherein each reaction is carried out in one reactor; 2) the method is realized by using a reactor (such as a flask, a reaction kettle and the like), wherein each step of reaction is sequentially completed, a plurality of raw materials are sequentially added according to the reaction progress in the reaction process, namely, after each step of reaction, the raw materials are stopped to wait for further addition of the raw materials for the subsequent reaction. Some documents also refer to mode 2) as continuous (continuous), which is also intermittent in nature because of "standing" in the process, waiting for the addition, or requiring adjustment to a suitable temperature for the next reaction (e.g., warming, cooling, or holding).

The batch process mainly has the following problems:

1. the batch operation efficiency is not high, the reaction time is very long, the production period is very long, and the product quality is different.

2. Because of the nitration reaction, a large amount of concentrated sulfuric acid and concentrated nitric acid are used, and a certain amount of explosive polynitro products are generated, the intermittent process has great potential safety hazard.

3. Nitration reactions are strong exothermic reactions, are one of the critical and supervised dangerous chemical processes in eighteen types of countries, and require a reactor with good heat exchange performance to ensure that the reaction does not fly to temperature. If the temperature is too high, side reactions increase and the yield decreases. The existing intermittent process realizes the control of the reaction temperature mainly by controlling the adding speed of mixed acid and combining with a corresponding heat transfer device, thus greatly prolonging the operation time, not only reducing the production efficiency, but also not solving the problem of process safety fundamentally. Namely, the safety, the product yield and the quality stability of the batch process are all needed to be improved urgently.

4. The batch process inevitably brings about a Scaling up Effect (Scaling up Effect), which brings about a great obstacle to the scale-up of industrial production. The amplification effect refers to the research results obtained from chemical process (i.e. small scale) experiments (e.g. laboratory scale) using small equipment, and the results obtained from large scale production equipment (e.g. industrial scale) under the same operation conditions are often very different. The effect on these differences is called the amplification effect. The reason for this is mainly that the temperature, concentration, material residence time distribution in small-scale experimental facilities are different from those in large-scale facilities. That is, the results of the small scale experiments cannot be completely repeated on an industrial scale under the same operating conditions; to achieve the same or similar results on an industrial scale as in small scale experiments, process parameters and operating conditions need to be changed by optimal adjustment. For chemical processes, the amplification effect is a difficult and urgent problem to solve. If not solved, the production process and the product quality have great uncertainty, and firstly, the quality of downstream products is directly unstable and is difficult to control; secondly, the uncertainty can bring about the fluctuation of the technological parameters in the production process, so that the production process cannot be effectively controlled, the production safety cannot be ensured, and a plurality of potential safety hazards are buried in the production process.

Chinese patent CN105418433A describes that 3, 4-dichloronitrobenzene is prepared by a continuous tank process for chloronitrobenzene, and because the tank process inevitably has amplification effect, and because a large amount of chlorine is used, on one hand, the requirement on equipment is high, a reaction tank needs to be replaced periodically, the production cost is greatly increased, the production efficiency is influenced, and on the other hand, great potential safety hazard exists.

Chinese patent CN102675120A describes that 3, 4-dichloronitrobenzene is synthesized by using a solid acid catalyst, which is also a kettle type process, and during industrial amplification, only a method of multiple step-by-step amplification can be adopted, and in order to obtain a result consistent with the laboratory scale, process conditions and parameters need to be adjusted and optimized in each amplification process, which greatly consumes manpower, material resources and project time, has a greatly uncertain amplification effect, and requires dropwise addition of nitric acid, so that safety cannot be guaranteed, reaction needs 6-8 hours, and production efficiency is extremely low.

Chinese patent CN107417536A describes the continuous synthesis of p-chloronitrobenzene, the first stage reaction temperature is 100-200 ℃, the reaction time is 15-50min, the second stage reaction temperature is 10-100 ℃, the reaction time is 1-50min, the overall reaction temperature is high, the reaction time is long, and the middle liquid separation step is needed, the operation is complex, the production period is very long, and the safety of the reaction temperature is high.

Chinese patent CN107973720A describes that p-chloronitrobenzene is continuously synthesized, the reaction temperature is 0-50 ℃, the reaction time is 30-120s, raw materials and mixed acid need to be preheated, and a continuous post-treatment process is not included, the post-treatment still adopts a kettle type process, the efficiency is low, and the whole production period is long.

In conclusion, the existing production process of 3, 4-dichloronitrobenzene has a plurality of problems: even if the dropping speed of the mixed acid is controlled in the kettle type process, the risk of temperature runaway and even explosion still exists, so that the process has great potential safety hazard. In addition, the existing processes have amplification effects of different degrees, so that a large amount of manpower and material resources are consumed and a lot of uncertainty exists when the industrial amplification is carried out; the reliability of the process after amplification has problems, so that the product quality is unstable and difficult to control; and the production process lacks flexibility and has potential safety risks; there are also some continuous processes, which are only directed at the reaction steps, but have no continuous post-treatment process, resulting in overlong total production time and low yield, reducing production efficiency, which all increase the difficulty of industrialization.

Therefore, a full continuous flow catalytic production process for reaction and post-treatment of 3, 4-dichloronitrobenzene, which is simple and safe to operate, high-efficiency, easy to produce on a large scale and free of amplification effect, needs to be found.

The in-situ production means that a manufacturer places equipment to a position close to or at the same position of an end consumer (or a downstream user) for production, so that a plurality of intermediate links such as storage, logistics and the like from the manufacturer to the end consumer (or the downstream user) are reduced to a great extent, and a great amount of cost is saved. The storage and transport of small quantities of product, for example from one plant of a factory to another, from production plants for the synthesis of products and to downstream production plants, is not avoided in the field of production. The on-line manufacturing is used as one of the local manufacturing, which means that the production and the use of the product are performed simultaneously, and the on-line manufacturing is seamlessly connected with the downstream process and synchronously linked, so that the flexible production mode (flexible manufacturing) of the product, namely, the product-to-use and the ready-to-use is realized. The on-line production is realized by means of plug-and-product system. The production and use are carried out simultaneously; the production is carried out at any time, namely, the production is carried out at any time as required, waiting is not needed, and zero stock is produced as required; the plug-and-play production device can obtain products immediately after the production device is started, produce according to needs and stop after the needs are met. The production time of the online production can be shortened to more than ten minutes or even within several minutes, and the seamless butt joint with the production equipment and the production process of a downstream user can be realized, so that the storage and the transportation of products are fundamentally avoided, the cost is saved, the production safety is improved, and the production efficiency is also improved. The production time refers to the time required from the entry of the feedstock into the reactor to the output of the product on the market, including the reaction time and the work-up time, also known as the residence time (residence time) in a continuous flow process. As a highly flexible production mode, the online production can save a large amount of storage, logistics and other costs as other production modes in situ, can effectively meet the requirements of rapid, personalized and customized products, and also meets the development direction of the fourth industrial revolution leading to industrialization 4.0 and intelligent manufacturing.

Disclosure of Invention

The technical problem to be solved by the present invention is to provide a reaction system, which can realize a full continuous flow production process of 3, 4-dichloronitrobenzene in the reaction system, the process is simple, safe and efficient, has no amplification effect, can produce 3, 4-dichloronitrobenzene with high yield and content, has stable quality, is easy for mass production, and can greatly reduce the production cost and improve the production safety of 3, 4-dichloronitrobenzene.

The full continuous flow production process is one kind of continuous process, is a fast and efficient full flow continuous process, has the characteristics of short time consumption, high efficiency, easy operation and the like, continuously adds raw materials in the process, continuously produces and prepares products, continuously flows materials (namely reaction mixture containing the raw materials, intermediates, products, solvents and the like) in the process, does not have interruption and stay waiting, namely the products are continuously produced, and is a 'flow line' type chemical production process. When the process operation reaches a steady state, the state parameters of the material composition, the temperature and the like at any position in the reactor do not change along with the time, and the process is a steady state process, so the production process and the product quality are stable. In a process involving multiple reactions, if some of the steps are continuous or simply connected, the process may be referred to as a semi-continuous process; a full continuous flow process is only possible if all steps are continuous and the material is flowing continuously throughout the process, i.e. the feed is continuously added and the product is continuously obtained.

In order to realize the aim, the invention provides an online full-continuous flow synthesis process for directly preparing 3, 4-dichloronitrobenzene under the action of a catalyst. The full continuous flow synthesis process adopts an integrated full continuous flow reaction system. The full continuous flow synthesis process is a plug-and-play type, namely reaction raw materials are uninterruptedly added into a feed inlet positioned at the foremost end of the integrated full continuous flow reaction system, and a final product 3, 4-dichloronitrobenzene is uninterruptedly obtained from a discharge outlet positioned at the rearmost end of the integrated full continuous flow reaction system. Wherein the reaction raw materials comprise a catalyst, a reaction substrate, sulfuric acid and nitric acid, and the reaction raw materials are simultaneously and uninterruptedly input into the integrated full continuous flow reaction system from the feed inlet.

The integrated full-continuous flow reaction system is formed by connecting a nitration unit and a post-treatment unit in series, wherein the nitration unit completes the mixing of mixed acid and reaction substrate and the nitration reaction process, and the post-treatment unit completes the cleaning and liquid separation process. The nitration reaction unit is formed by connecting a plurality of reactors in series, and is at least divided into a temperature zone 1 and a temperature zone 2 according to process control, wherein each temperature zone at least comprises one reactor; the post-treatment unit is at least divided into two temperature zones, namely a temperature zone 3 and a temperature zone 4, each temperature zone is formed by alternately connecting a plurality of wire mesh separators and reactors in series, the reactors are used for mixing and cleaning materials, the oil-water separators are used for online separation, and the two are mutually cooperated to finish the cleaning and liquid separation process of post-treatment.

The full continuous flow synthesis process comprises the following steps:

(a) inputting a reaction substrate mixed with a catalyst, sulfuric acid and nitric acid into a nitration reaction unit of the integrated full continuous flow reaction system through a feed inlet respectively, sequentially flowing through a temperature zone 1 and a temperature zone 2, and stirring and mixing processes are carried out in the temperature zone 1;

(b) and (3) allowing the nitration liquid to flow out of the temperature zone 2, enter a post-treatment unit, sequentially flow through the temperature zone 3 and the temperature zone 4 for post-treatment, and output from a discharge hole to obtain a final product, namely the 3, 4-dichloronitrobenzene.

The catalyst is selected from [ bNEt₃SO₃H][H₂PO₄]、[bNEt₃SO₃H][HSO₄]And [ bNEt₃SO₃H][Cl]One kind of (1). Further preferably [ bNEt ]₃SO₃H][HSO₄](ii) a The reaction substrate was o-dichlorobenzene (abbreviated as: ODCB).

Further, the mass ratio of the catalyst to the reaction substrate is preferably 0.5 to 2%, and more preferably 1%. The flow rate of the reaction substrate mixed with the catalyst in the step a) flowing into the reaction system from the feeding hole is 10-40 g/min, preferably 15-40 g/min, and more preferably 18-38 g/min.

Further, the molar ratio of the sulfuric acid to the reaction substrate is 1.3:1 to 2.5:1, preferably 1.4:1 to 2:1, and more preferably 1.5:1 to 1.8: 1. The flow rate of the sulfuric acid flowing into the reaction system from the feeding hole in the step a) is 10-50 g/min, preferably 12-48 g/min, and more preferably 14-45 g/min.

Further, the molar ratio of the nitric acid to the reaction substrate is 0.8:1 to 1.2:1, preferably 0.85:1 to 1.1:1, and more preferably 0.95:1 to 0.98: 1. The flow rate of the nitric acid flowing into the reaction system from the feeding hole in the step a) is 5-20 g/min, preferably 5-18 g/min, and more preferably 5-15 g/min.

Further, the mass concentration of the sulfuric acid is 90% to 98%, preferably 93% to 98%, more preferably 95% to 98%.

Further, the mass concentration of the nitric acid is 90-98%, preferably 93-98%, more preferably 95-98%.

The time of the full continuous flow synthesis process is less than or equal to 120s, and preferably, the production time is 10-110 s; more preferably, the production time is 20-100 s; more preferably, the production time is 30-90 s. The total continuous flow synthesis process time is the time of the whole process that reaction raw materials are input from the feed inlet, the nitration reaction and the post-treatment process are completed through the integrated total continuous flow reaction system, and the reaction raw materials are output from the discharge outlet. Wherein the time ratio of the respective temperature zones is preferably: temperature zone 1: temperature zone 2: temperature zone 3: the temperature zone 4 is 5:8:5: 5.

Further, the temperature of the temperature zone 1 is 5-60 ℃, preferably 5-50 ℃, more preferably 5-40 ℃, more preferably 5-30 ℃, and more preferably 5-20 ℃.

Further, the temperature of the temperature zone 2 is 40-100 ℃, preferably 50-100 ℃, more preferably 60-90 ℃, and more preferably 70-80 ℃.

Further, the temperature of the temperature zone 3 is 50-100 ℃, preferably 50-90 ℃, more preferably 50-80 ℃, more preferably 50-70 ℃, and more preferably 50-60 ℃.

Further, the temperature of the temperature zone 4 is 50-100 ℃, preferably 50-90 ℃, more preferably 50-80 ℃, more preferably 50-70 ℃, and more preferably 50-60 ℃.

Further, the full continuous flow synthesis process further comprises the following steps of: adding the catalyst into the reaction substrate and mixing uniformly.

Further, the reaction raw material preparation step further comprises a catalyst preparation step comprising:

first step, synthesis of ylide: 0.05mol of triethylamine was added to the flask, and equimolar 1, 4-butane sultone was added, and stirred at room temperature (25 ℃ C.) for one week to obtain a white solid salt, which was then suction-filtered, washed with ethyl acetate several times until the solid became white or pale yellow in color, and dried under vacuum at 60 ℃ to obtain a ylide [ bNEt3SO3H ].

Second, acidification of the ylide: weighing a certain amount of ylide [ bNEt ]₃SO₃H]Adding equal molar concentrated sulfuric acid or concentrated phosphoric acid or hydrochloric acid respectively, heating and stirring at 80 deg.C for 6 hr until solid salt is completely dissolved, and rotary steaming at 80 deg.C for 1 hr to remove water to obtain ionic liquid [ bNEt₃SO₃H][HSO₄]Or [ bNEt₃SO₃H][H₂PO₄]Or [ bNEt₃SO₃H][Cl]。

Further, the yield of the 3, 4-dichloronitrobenzene is more than or equal to 90 percent; preferably, the yield of the 3, 4-dichloronitrobenzene is more than or equal to 93 percent; more preferably, the yield of the 3, 4-dichloronitrobenzene is more than or equal to 95 percent.

Further, the content of the 3, 4-dichloronitrobenzene is more than or equal to 93 percent; preferably, the content of the 3, 4-dichloronitrobenzene is more than or equal to 95 percent; the content of the 3, 4-dichloronitrobenzene is more than or equal to 97 percent.

The invention also provides an integrated full-continuous flow reaction system of the 3, 4-dichloronitrobenzene, which adopts a unitized structure and comprises a nitration unit and a post-treatment unit, wherein the units are connected in series. Wherein: the nitration unit is used for realizing the reaction of a reaction substrate, sulfuric acid and nitric acid to generate 3, 4-dichloronitrobenzene, and the post-treatment unit is used for neutralizing and cleaning the 3, 4-dichloronitrobenzene.

Each unit comprises at least one temperature zone, and the temperature zones are mutually connected in series; each temperature zone comprises at least one reactor module or reactor module group, wherein the reactor module group is formed by connecting a plurality of reactor modules in series or in parallel; each reactor module comprises at least one reactor.

The material flow in the full continuous flow reaction system completes the front-to-back conveying of the material by means of the pressure drop of the reactor.

Each temperature zone of the post-treatment unit further comprises a wire mesh separator, the wire mesh separators and the reactor modules are alternately connected in series, the wire mesh separators are used for continuous online oil-water separation, the reactor modules connected in series complete mixed cleaning of materials, and the wire mesh separators and the reactor modules complete cleaning and liquid separation processes of post-treatment in a mutual cooperation mode.

The integrated full-continuous flow reaction system also comprises at least one feeding hole and at least one discharging hole, and the feeding hole and the discharging hole are positioned at the foremost end and the rearmost end of the integrated full-continuous flow reaction system.

Further, the reactor is any reaction device capable of realizing a continuous flow process, and is selected from any one or more of a Microreactor (micro reactor), a Tandem loop reactor (Tandem loop reactor) and a Tubular reactor (Tubular reactor). The microreactor, also known as a microstructured reactor or microchannel reactor, is a device in which chemical reactions take place in a confined region having a prevalent lateral dimension of 1mm or less, most typically in the form of a microscale channel. The coil reactors are connected in series, namely the coil reactors are connected in series by pipelines, wherein the coil reactors are in the form of coils made of tubular reactors. The tubular reactor is a tubular continuous operation reactor with a large length-diameter ratio, and the reactor can be long; the device can be a single tube or a plurality of tubes connected in parallel, can be an empty tube or a filling tube.

Furthermore, the material channel in the reactor is made of monocrystalline silicon, special glass, ceramics, stainless steel or metal alloy coated with a corrosion-resistant coating, and polytetrafluoroethylene.

Further, the nitration unit of the full continuous flow reaction system comprises 2 temperature zones, namely a temperature zone 1 and a temperature zone 2; the post-treatment unit comprises 2 temperature zones, namely a temperature zone 3 and a temperature zone 4.

Further, the temperature zone 1 comprises 1 reactor module, the temperature zone 2 comprises 2 reactor modules, the temperature zone 3 is formed by connecting a wire mesh separator and a reactor module in series, and the temperature zone 4 is formed by alternately connecting two wire mesh separators and a reactor module in series. Each reactor module comprises at least one reactor, and the number of reactors forming each reactor module is determined by the length of a material channel of the reactor and the process time of reaction materials in the module (namely the time of the materials passing through the module).

Further, the reactor in the temperature zone 1 has a stirring function for stirring and mixing the reaction raw materials.

Further, the reactors in the full continuous flow reaction system can realize temperature control. Further, the temperature of the reactor in the temperature zone 1 can be controlled at least at 5-60 ℃.

Further, the temperature of the reactor in the temperature zone 2 can be controlled at least at 40-100 ℃.

Further, the temperature control of 50-100 ℃ can be realized at least by the reactors of the temperature zone 3 and the temperature zone 4.

The invention provides a technical scheme for directly and fully continuously producing 3, 4-dichloronitrobenzene from a reaction substrate, wherein a plurality of reactants are continuously input into a reaction system, and reaction products are continuously collected. The yield of the reaction product is improved by selecting and using a proper catalyst; meanwhile, by means of the temperature zone division and temperature setting of the functional units, configuration optimization of residence time of each temperature zone and the synergistic effect of the functional units, the full reaction can be realized in a short time, so that the total reaction time is shortened to 120s, and the efficiency of the process is greatly improved.

The full continuous flow synthesis process adopts continuous processes in the nitration stage and the post-treatment stage, and has good stability and reliability, so that the product quality is stable and the reproducibility is good; the process has no amplification effect, solves the problem of the amplification effect in the industrialization of the 3, 4-dichloronitrobenzene continuous flow process, and greatly reduces the difficulty of industrial application; when the method is industrially amplified, the required production scale can be amplified at one time without complicated multiple step-by-step amplification and adjustment and optimization of process conditions and parameters, so that manpower, material resources and project development time are greatly saved; in industrial production, the production scale of the product can be flexibly changed, the process conditions and parameters do not need to be readjusted and optimized, and the flexibility of the production process is good; the production process is stable and reliable due to no amplification effect, the product quality is not influenced by the fluctuation of process conditions and parameters, and the product quality is easy to control; this also greatly improves the safety of the production process.

In order to meet the conditions of the full-continuous flow process, the integrated full-continuous fluidization reaction system provided by the invention adopts a modular structure, and the full-continuous flow process is realized by designing the organization mode and the number of modules, the modules contained in each temperature zone, and developing targeted process conditions and parameters, including the division and the temperature setting of each temperature zone, and the synergistic action of various factors such as multi-stage oil-water separation and the like. The integrated full-continuous fluidized reaction system can further combine the temperatures with the material concentration, the material proportion and the material flow rate to match with the reaction process, thereby obtaining better process effect.

Meanwhile, the integrated full-continuous flow reaction system greatly saves the land for a factory building due to small volume and small occupied area.

In conclusion, compared with the prior art, the invention has the following beneficial effects:

1. the production process of the invention is completely different from the prior art, only one-step reaction is carried out, the reaction process and the post-treatment process are integrated into a set of complete production process, the product is directly prepared in a short time (within 120 s), and the high-quality and high-efficiency production is realized.

2. The production process is safe and efficient, the yield and the content of the prepared 3, 4-dichloronitrobenzene are high, the production cost is greatly reduced, the production safety of the product is improved, and the high-efficiency, high-quality and large-scale production of the 3, 4-dichloronitrobenzene is realized.

3. The method solves the problem of industrial amplification of the 3, 4-dichloronitrobenzene continuous flow process, has no amplification effect in the production process, greatly reduces the difficulty of industrial application, can be amplified to the required production scale once without complicated multiple step-by-step amplification and adjustment and optimization of process conditions and parameters when being amplified to the industrialization, and greatly saves manpower, material resources and project development time.

4. The safety of the production process is greatly improved, and the relatively small liquid holdup and excellent heat transfer characteristic of the continuous flow reactor and the relatively short reaction time (within 120 s) ensure that the process is safer.

5. Compared with the prior art, the method has the advantages that the reaction time is greatly shortened, the reaction time is shortened by 95 percent, and the reaction efficiency is greatly improved.

6. In the integrated continuous flow reactor, the product quality is stable and the reproducibility is good because the flow rate is stable and the production process is stable.

7. The integrated continuous flow reactor has small volume and small occupied area, and greatly saves the land for a factory building.

Drawings

Fig. 1 is a schematic diagram of the integrated full continuous flow reaction system of the present invention.

FIG. 2 is a schematic view of a full continuous flow process for synthesizing 3, 4-dichloronitrobenzene according to an embodiment of the present invention.

Detailed Description

The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.

The concentrations in the examples of the invention are mass concentrations, and the products are detected by Gas Chromatography (GC). As can be seen from the following examples of the present invention, when the process parameters are controlled within the appropriate ranges in the tables of the following examples, the target product, 3, 4-dichloronitrobenzene, is obtained with a 3, 4-dichloronitrobenzene content of 93% or more, a 2, 3-dichloronitrobenzene content of less than 7%, and other dinitrobenzene contents of less than 0.1%, and the dinitrobenzene impurities are 2, 3-dichloro-1, 4-dinitrobenzene, 1, 2-dichloro-3, 5-dinitrobenzene, 1, 2-dichloro-4, 5-dinitrobenzene, and 1, 2-dichloro-3, 4-dinitrobenzene. As shown in FIG. 1, a schematic diagram of the full continuous flow reaction system of the present invention is shown, the full continuous flow reaction system is of a plug-and-play type, a plurality of reaction raw materials are continuously fed into the reaction system, and reaction products are continuously collected. FIG. 2 is a schematic diagram of the full continuous flow process for synthesizing 3, 4-dichloronitrobenzene in the following examples, and it can be seen that the full continuous flow reaction system used in the examples is composed of a nitration unit and a post-treatment unit which are connected in series. The nitration unit comprises 2 temperature zones which are respectively a temperature zone 1 and a temperature zone 2; the post-treatment unit comprises 2 temperature zones, namely a temperature zone 3 and a temperature zone 4. The temperature zone 1 comprises 1 reactor module, i.e. the module 1 shown in fig. 2, the temperature zone 2 comprises 2 reactor modules, i.e. the module 2 and the module 3 in fig. 2, the temperature zone 3 is formed by connecting a wire mesh separator and a reactor module, i.e. the module 4 in fig. 2 in series, and the temperature zone 4 is formed by connecting two wire mesh separators and a reactor module, i.e. the module 5 in fig. 2 in series alternately.

In operation, feedstock 1 (ODCB mixed with catalyst), feedstock 2 (concentrated sulfuric acid) and feedstock 3 (concentrated nitric acid) were fed sequentially through a constant flow pump into a full continuous flow reaction system at feed rates detailed in the tables below, where feed rate 1 represents the feed rate of feedstock 1, feed rate 2 represents the feed rate of feedstock 2, and feed rate 3 represents the feed rate of feedstock 3. Entering a temperature zone 1, stirring and mixing, and then carrying out nitration reaction in a temperature zone 2 until the reaction is complete; and (3) allowing the reaction liquid flowing out of the temperature zone 2 to enter a temperature zone 3 and a temperature zone 4 for post-treatment to obtain a product. The process temperature is controlled by taking a temperature zone as a unit, the reaction time is controlled by controlling the flow time proportion of each module and the total full continuous flow synthesis process time, wherein the time ratio of each module is as follows: module 1: and (3) module 2: and a module 3: and (4) module: module 5 was 5:4:4:5:5 and the full continuous flow synthesis process times for each example are shown in the tables below. The various process parameters for specific examples are shown in the tables below, wherein catalyst usage refers to the mass percent of catalyst to reaction substrate.

Table 1: examples 1-6 temperature zones 1 were screened.

Table 2: examples 7-12 temperature screening of zone 2.

Table 3: examples 13-18 temperature screening zone 3.

Table 4: examples 19-24 temperature zones 4 were screened.

Table 5: examples 25-28 screening concentrated sulfuric acid concentrations.

Table 6: examples 29-32 screening concentrated nitric acid concentrations.

Table 7: examples 33-38 screening of the molar ratio of concentrated sulfuric acid.

Table 8: examples 39-44 the molar ratios of concentrated nitric acid were selected.

Table 9: examples 45-48 the catalyst species were screened.

Table 10: examples 49-52 the catalyst amounts were screened.

Table 11: examples 53-56 flow rates were screened.

Claims

1. An integrated full-continuous-flow reaction system of 3, 4-dichloronitrobenzene, which is characterized in that:

the integrated full-continuous flow reaction system adopts a unitized structure and comprises a nitrification unit and a post-treatment unit, wherein the units are connected in series; wherein: the nitration unit is used for realizing the reaction of a reaction substrate, sulfuric acid and nitric acid to generate the 3, 4-dichloronitrobenzene, and the post-treatment unit is used for neutralizing and cleaning the 3, 4-dichloronitrobenzene;

each unit comprises at least one temperature zone, and the temperature zones are mutually connected in series;

each temperature zone comprises at least one reactor module or reactor module group, wherein the reactor module group is formed by connecting a plurality of reactor modules in series or in parallel;

the reactor module comprises at least one reactor;

2. The integrated full continuous flow reaction system of 3, 4-dichloronitrobenzene according to claim 1, wherein: each temperature zone of the post-treatment unit further comprises a wire mesh separator, the wire mesh separators and the reactor modules are alternately connected in series, the wire mesh separators are used for continuous online oil-water separation, the reactor modules connected in series complete mixed cleaning of materials, and the wire mesh separators and the reactor modules complete cleaning and liquid separation processes of post-treatment in a mutual cooperation mode.

3. The integrated full continuous flow reaction system of 3, 4-dichloronitrobenzene according to claim 1, wherein: the nitration unit of the full continuous flow reaction system comprises 2 temperature zones which are respectively a temperature zone 1 and a temperature zone 2; the post-treatment unit comprises 2 temperature zones, namely a temperature zone 3 and a temperature zone 4.

4. The integrated full continuous flow reaction system of 3, 4-dichloronitrobenzene according to claim 3, wherein: the reactor in the temperature zone 1 has a stirring function and is used for stirring and mixing reaction raw materials.

5. The integrated full continuous flow reaction system of 3, 4-dichloronitrobenzene according to claim 3, wherein: the temperature zone 1 comprises 1 reactor module, the temperature zone 2 comprises 2 reactor modules, the temperature zone 3 is formed by connecting a wire mesh separator and a reactor module in series, and the temperature zone 4 is formed by alternately connecting two wire mesh separators and a reactor module in series.

6. The integrated full continuous flow reaction system of 3, 4-dichloronitrobenzene according to claim 1, wherein: the reactor is any reaction device capable of realizing a continuous flow process, and is selected from one or more of a microreactor, a serial-connection coil reactor and a tubular reactor.