Continuous synthesis method of 1-nitroanthraquinone

Abstract

The invention belongs to the field of organic chemical synthesis, and relates to a method for continuously synthesizing 1-nitroanthraquinone. A microreactor continuous flow circulation system is adopted, the raw material anthraquinone is prepared into slurry, and the slurry reacts with concentrated sulfuric acid with a set feeding flow in the continuous flow circulation system to realize continuous nitration of anthraquinone. The process for continuously synthesizing the 1-nitroanthraquinone by using the method is simple, the time is greatly shortened compared with that of a kettle type process, the requirement on equipment temperature control is lower, the solid slurry can continuously flow in the pipeline without blocking the pipeline, the reaction operability is improved, the product selectivity is good, and the raw material conversion rate is high. The microreactor continuous flow circulation system adopted by the invention has better mass and heat transfer efficiency, the reaction temperature control is more accurate, the explosion risk is reduced, and the operation process is safer.

Description

Technical Field

[0001] The present invention relates to the field of organic synthesis, and in particular to a continuous synthesis method of 1-nitroanthraquinone Background Art

[0002] Anthraquinone dyes are the second largest category of dyes after azo dyes in terms of usage, and are usually used in situations that require extreme performance, color fastness, or special colors. Nitroanthraquinone prepared by the anthraquinone nitration reaction is one of the important raw materials for the production of various anthraquinone dyes, but there are many nitration reaction pathways for anthraquinone. During the reaction, mononitration and dinitration reactions occur simultaneously, and two mononitration isomers and six dinitration isomers are generated. The selectivity of a single nitration product is low, so cumbersome separation and purification steps must be performed to obtain a single nitration product. The nitration reaction is one of the oldest reactions in industry, and mature methods for anthraquinone nitration reactions are already available in industry. However, due to its complex reaction pathway and the inherent defects of traditional kettle nitration reactions, research on the laws of the anthraquinone nitration reaction process is still limited.

[0003] The nitration reaction is a process with a fast reaction rate and strong exothermicity. The kettle dripping method is the current conventional operation of the nitration reaction. However, the heat and mass transfer capacity of the kettle reactor is relatively inefficient and the liquid holdup is high, which makes it difficult to effectively control the nitration reaction process. Micro-reaction continuous flow technology has been widely studied in synthetic chemistry, providing a good opportunity for the development of safe and controllable nitration reaction processes and the effective exploration of reaction laws. The micro-reaction technology characterized by microscale effectively utilizes the advantages of the high specific surface area in the reactor, can achieve good heat and mass transfer and precise control of process parameters, and the reaction process is easy to scale up and can be inherently safe. Therefore, it has the potential to solve the problems of high safety risks, high energy consumption, low reaction efficiency, and heavy environmental pollution in the current chemical production process.

[0004] At present, concentrated sulfuric acid and 1,2-dichloroethane are mostly used as solvents in the process of preparing anthraquinone by micro-reaction continuous flow. When concentrated sulfuric acid is used as the solvent, a large amount of concentrated sulfuric acid is used to dissolve the anthraquinone. The advantage of this method is that the raw materials are completely dissolved and there is no solid in the entire reaction process. There will be no pipeline blockage and uneven flow of the metering pump, and the reaction speed is also fast. However, due to the large amount of concentrated sulfuric acid used and the fast reaction speed, the by-products are difficult to control, the selectivity of the reaction is low, and the use of a large amount of concentrated sulfuric acid will produce a large amount of waste acid, which increases the cost of post-processing. When 1,2-dichloroethane is used as the solvent, the kettle process is mainly used. Due to the limited heat exchange of the reactor, concentrated sulfuric acid can only be added slowly. Therefore, although the amount of concentrated sulfuric acid used is low, the reaction speed is slow, and it can only be generated intermittently, and the synthesis efficiency is low. If generated by the tubular method, anthraquinone is difficult to dissolve in dichloroethane, and the formed slurry is difficult to be smoothly transported by the metering pump. It is very easy to cause pipeline blockage, abnormal metering pump flow and metering pump failure to deliver liquid. In addition, the tubular method still cannot solve the problem of slow reaction speed and low anthraquinone conversion rate. If anthraquinone is to be converted more completely, a longer delay pipeline is required, which greatly increases the equipment cost. The existing technology has no effective solution to this problem. Summary of the invention

[0005] In order to solve the problems in the prior art, the applicant has conducted a thorough investigation of the prior art. The applicant has found that in the scheme with 1,2-dichloroethane as the solvent, the form in which sulfuric acid is added to the slurry (including how the sulfuric acid is added, the feeding speed, the mixing method, etc.) is the key to whether the product can be efficiently and continuously synthesized. Based on this, the present invention proposes a continuous synthesis method for 1-nitroanthraquinone. The method utilizes a micromixer to realize the continuous synthesis of anthraquinone nitration reaction, and transforms the kettle synthesis process that originally required a long time and complicated steps into a continuous synthesis process. The process is simple, the reaction time is short, the temperature control of the equipment is more precise, and the risk of explosion in the nitration reaction is avoided.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] (1) mixing raw materials anthraquinone, 1,2-dichloroethane and fuming nitric acid uniformly to form a slurry solution; and using concentrated sulfuric acid as a second feed liquid;

[0008] (2) adding the slurry solution into a stirred reactor with heating and heat preservation functions, starting a peristaltic pump to allow the slurry solution to flow out of the stirred reactor, and continuously flowing and circulating in a circulation system consisting of a micro mixer, a heating delay coil, and a stirred reactor;

[0009] (3) transporting the second feed liquid to a micro mixer by using a horizontal flow pump, and mixing it with the circulating slurry solution to undergo a nitration reaction, thereby obtaining a mixed material;

[0010] The ratio of the feed flow rate of the second liquid to the flow rate of the material in the circulation system is 1:(140-500); the mixed material continues to flow through the heating delay coil and the stirring reactor, and is mixed with the concentrated sulfuric acid again when it flows through the micro mixer next time, and the cycle is repeated until all the required concentrated sulfuric acid is pumped into the mixed material, and then the operation of the advection pump is stopped;

[0011] (4) continuing to circulate the mixed material between the stirred reactor, the micro-mixer and the heating delay coil for a period of time to allow the raw materials to fully react to obtain a reaction solution containing 1-nitroanthraquinone;

[0012] (5) disconnecting the circulation system, placing the feed pipe of the peristaltic pump into 1,2-dichloroethane, and pushing all the reaction liquid containing 1-nitroanthraquinone in the pipe into the reactor through 1,2-dichloroethane;

[0013] (6) adding aqueous ammonia to the reaction solution containing 1-nitroanthraquinone and mixing thoroughly, adjusting the pH value of the reaction solution to 6-7, and controlling the temperature in this process not to exceed 40° C.;

[0014] (7) The reaction solution after pH adjustment is post-treated to obtain a pure product of 1-nitroanthraquinone.

[0015] Compared with the prior art, the beneficial effects of the present invention include:

[0016] (1) The present invention realizes the continuous synthesis of anthraquinone nitration reaction, transforming the original kettle synthesis process that requires a long time and has complicated steps into a continuous synthesis process with a simple process and short reaction time. It also avoids excessive nitration and reduces the generation of dinitroanthraquinone by-products.

[0017] (2) The present invention adopts a peristaltic replacement metering pump to solve the problem of difficult transportation, and reduces the length of the delay pipeline by circulating, and the accuracy requirement of the pump flow is also greatly reduced.

[0018] (3) According to experimental findings, the feed rate of concentrated sulfuric acid in the anthraquinone nitration process has a significant effect on the selectivity of the reaction. The faster the feed rate of concentrated sulfuric acid, the more favorable the formation of the byproduct 2-nitroanthraquinone, thereby reducing the selectivity of the target product. However, the processes currently reported for anthraquinone nitration all add the required amount of concentrated sulfuric acid at one time, which makes the selectivity of the anthraquinone nitration micro-reaction process not high. The present invention adopts the method of mixing the raw materials, nitric acid and solvent and then circulating them, then adding concentrated sulfuric acid to the circulation system through a metering pump, and adjusting the feed rate of concentrated sulfuric acid through the metering pump to achieve the purpose of reducing byproducts and improving selectivity.

[0019] (4) Continuous micro-reaction refers to the process of continuously producing chemicals and drugs in micro-reactor pipes with sizes in the micrometer and millimeter range. Continuous flow micro-reactors have good heat and mass transfer performance and low liquid holdup, and are safe, environmentally friendly, efficient and low in energy consumption. The continuous reaction of the present invention is easy to monitor and control the reaction process. The reaction is carried out in a micro-reactor, and its smaller characteristic size enhances the heat and mass transfer effect of the reaction materials, makes the temperature control of the equipment more accurate, reduces side reactions, improves product selectivity, and avoids the safety risk of explosion in nitration reactions. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the reaction device and process of the present invention. DETAILED DESCRIPTION

[0021] The present invention is further described and illustrated below in conjunction with specific embodiments. The embodiments are merely exemplary of the present disclosure and do not define the scope of limitation. The technical features of each embodiment of the present invention may be combined accordingly without conflicting with each other.

[0022] like Figure 1 As shown, the embodiment of the present invention provides a continuous synthesis method of 1-nitroanthraquinone and a corresponding continuous synthesis device. The device mainly includes a circulation system consisting of a peristaltic pump, a micro mixer, a heating delay coil, and a reactor, and a sulfuric acid delivery pipeline consisting of a horizontal flow pump and a preheating tube; the mixer adopts a T-type micro mixer, and the dispersion scale of the micro mixer is 250-750μm; the volume ratio of the circulating material in the delay coil and the reactor is 8:2; the sulfuric acid delivery pipeline is connected to the micro mixer.

[0023] Based on the above device, the continuous synthesis method of 1-nitroanthraquinone proposed by the present invention mainly includes the following steps:

[0024] (1) mixing raw materials anthraquinone, 1,2-dichloroethane and fuming nitric acid uniformly to form a slurry solution; the mass ratio of anthraquinone to fuming nitric acid is 1:(0.3-0.4), and the mass ratio of anthraquinone to 1,2-dichloroethane is 1:(1-3); and concentrated sulfuric acid is used as the second feed liquid;

[0025] (2) adding the slurry solution into a stirred reactor with heating and heat preservation functions, starting a peristaltic pump to allow the slurry solution to flow out of the stirred reactor, and continuously flowing and circulating in a circulation system consisting of a micro mixer, a heating delay coil, and a stirred reactor; the flow rate of the slurry solution is 20-50 mL / min;

[0026] (3) transporting the second feed liquid to a micro mixer by using a horizontal flow pump, and mixing it with the circulating slurry solution to undergo a nitration reaction, thereby obtaining a mixed material;

[0027] The temperature of the mixer, the heating delay coil and the reactor is kept consistent, and the temperature range is 25-45°C; the flow rate of the second liquid is 0.1-5mL / min; the feed flow rate of the second liquid and the flow rate of the material in the circulation system are 1:(140-500); the mixed material continues to flow through the heating delay coil and the stirring reactor, and is mixed with concentrated sulfuric acid again when it flows through the micro mixer next time, and the cycle is repeated until all the required concentrated sulfuric acid is pumped into the mixed material, and then the operation of the advection pump is stopped;

[0028] (4) continuing to circulate the mixed material between the stirred reactor, the micro-mixer and the heating delay coil for 1-4 hours to allow the raw materials to fully react to obtain a reaction solution containing 1-nitroanthraquinone;

[0029] (5) disconnecting the circulation system, placing the feed pipe of the peristaltic pump into 1,2-dichloroethane, and pushing all the reaction liquid containing 1-nitroanthraquinone in the pipe into the reactor through 1,2-dichloroethane;

[0030] (6) adding aqueous ammonia to the reaction solution containing 1-nitroanthraquinone and mixing thoroughly, adjusting the pH value of the reaction solution to 6-7, and controlling the temperature in this process not to exceed 40° C.;

[0031] 7.1) filtering the reaction solution containing 1-nitroanthraquinone, retaining the filter cake, and rinsing the filter cake with clean water to obtain a first crude product containing 1-nitroanthraquinone;

[0032] 7.2) The first crude product of 1-nitroanthraquinone is fully mixed with 1-3 times the mass of DMF, the temperature of the mixed solution is raised to 130° C. to dissolve all the solids, and then the temperature is slowly lowered to 30° C., and the cooling rate of the cooling process is 0.3-0.8° C. / min, so that 1-nitroanthraquinone is fully precipitated; and a first slurry containing 1-nitroanthraquinone is obtained;

[0033] 7.3) filtering the slurry containing 1-nitroanthraquinone by suction, retaining the filter cake, and rinsing the filter cake with DMF to obtain a second crude product of 1-nitroanthraquinone;

[0034] 7.4) adding 1-3 times the mass of DMF to the second crude product containing 1-nitroanthraquinone and mixing them thoroughly, stirring at room temperature for 3-8 hours to obtain a second slurry containing 1-nitroanthraquinone;

[0035] 7.5) The second slurry containing 1-nitroanthraquinone is filtered and the filter cake is retained. The filter cake is rinsed with DMF and then with clean water. The rinsed filter cake is then vacuum dried at 0-70° C. to obtain pure 1-nitroanthraquinone.

[0036] Example 1: Reference Figure 1 , a continuous synthesis method of 1-nitroanthraquinone, comprising the following steps:

[0037] (1) 24 g of anthraquinone, 48 g of dichloroethane and 9 g of fuming nitric acid are added sequentially into a stirred reactor with heating and heat preservation functions, and stirred evenly to prepare a feed liquid 1 (the feed liquid 1 is in the form of a slurry). The peristaltic pump is started and the flow rate is set to 35 mL / min, so that the feed liquid 1 flows out of the stirred reactor and continuously flows and circulates in a circulation system consisting of a micro mixer, a heating delay coil and a reactor, and the temperature in the micro mixer, the coil and the reactor is set to 35° C. The dispersion scale of the micro mixer is 500 μm.

[0038] (2) After the temperature of the feed liquid 1 reaches the specified temperature, start the horizontal flow pump to pass 18.4g of concentrated sulfuric acid into the mixer at a flow rate of 0.25mL / min to mix with the feed liquid 1 to cause nitration reaction. The reaction equation is as follows:

[0039]

[0040] (3) After all 18.4 g of concentrated sulfuric acid was added to the circulation system, the reaction solution was allowed to circulate in the reaction system for 2 h, and then the yield was calculated by liquid phase analysis. The yield of 1-nitroanthraquinone was 92.35% and the conversion rate of anthraquinone was 98.89%.

[0041] (4) disconnecting the circulation system, placing the feed pipe of the peristaltic pump into 1,2-dichloroethane, and pushing all the reaction solution 4 containing 1-nitroanthraquinone in the pipe into the reactor through 1,2-dichloroethane;

[0042] (5) Slowly add ammonia water into the reactor and mix thoroughly, and adjust the pH value of the reaction solution to 6.5. During this process, the temperature is controlled not to exceed 40°C;

[0043] (6) The reaction solution was then filtered, and the filter cake was retained. The filter cake was rinsed three times with clean water to obtain a crude product 1 containing 1-nitroanthraquinone, a total of 38 g;

[0044] (7) The crude product 1 of 1-nitroanthraquinone and 60 g of DMF were added to a recrystallization kettle, stirred and mixed thoroughly, and the temperature of the reactor was raised to 130° C. to dissolve all the solids, and then the temperature of the reactor was slowly lowered to 30° C. at a cooling rate of 0.55° C. / min to allow 1-nitroanthraquinone to be fully precipitated. A slurry 1 containing 1-nitroanthraquinone was obtained.

[0045] (8) The slurry 1 containing 1-nitroanthraquinone was filtered by suction, and the filter cake was retained. The filter cake was rinsed three times with DMF to obtain a crude product 2 of 1-nitroanthraquinone, totaling 34 g.

[0046] (9) The crude product 2 containing 1-nitroanthraquinone and 50 g of DMF were added into a pulping kettle and stirred to mix thoroughly. The mixture was stirred at room temperature for a certain period of time to obtain a slurry 2 containing 1-nitroanthraquinone.

[0047] (10) The slurry 2 containing 1-nitroanthraquinone was filtered and the filter cake was retained. The filter cake was rinsed three times with DMF and then rinsed three times with clean water. The rinsed filter cake was then vacuum dried to obtain 19.9 g of pure 1-nitroanthraquinone with a purity of 97.6%.

[0048] Example 2: Reference Figure 1 , a continuous synthesis method of 1-nitroanthraquinone, comprising the following steps:

[0049] (1) 24 g of anthraquinone, 24 g of dichloroethane and 7.5 g of fuming nitric acid were added sequentially into a stirred reactor with heating and heat preservation functions, and stirred evenly to prepare liquid 1. The peristaltic pump was started and the flow rate was set to 20 mL / min, so that liquid 1 flowed out of the stirred reactor and continuously circulated in the circulation system consisting of a micro mixer, a heating delay coil and a reactor, and the temperature in the micro mixer, the coil and the reactor was set to 25° C. The dispersion scale of the micro mixer was 250 μm.

[0050] (2) After the temperature of the feed liquid 1 reaches the specified temperature, the horizontal flow pump is started to pass 12 g of concentrated sulfuric acid into the mixer at a flow rate of 0.1 mL / min to mix with the feed liquid 1 to cause nitration reaction.

[0051] (3) After all 18.4 g of concentrated sulfuric acid was added to the circulation system, the reaction solution was allowed to circulate in the reaction system for 3 h, and then the yield was calculated by liquid phase analysis. The yield of 1-nitroanthraquinone was 92.8% and the conversion rate of anthraquinone was 98.30%.

[0052] (4) disconnecting the circulation system, placing the feed pipe of the peristaltic pump into 1,2-dichloroethane, and pushing all the reaction solution 4 containing 1-nitroanthraquinone in the pipe into the reactor through 1,2-dichloroethane;

[0053] (5) Slowly add ammonia water into the reactor and mix thoroughly, and adjust the pH value of the reaction solution to 6. During this process, the temperature is controlled not to exceed 40°C;

[0054] (6) The reaction solution was then filtered and the filter cake was retained. The filter cake was rinsed three times with clean water to obtain a crude product 1 containing 1-nitroanthraquinone, totaling 37.3 g;

[0055] (7) The crude product 1 of 1-nitroanthraquinone and 60 g of DMF were added to a recrystallization kettle and stirred to mix thoroughly. The temperature of the reactor was raised to 130° C. to dissolve all the solids. The temperature of the reactor was then slowly lowered to 30° C. at a cooling rate of 0.3° C. / min to allow 1-nitroanthraquinone to be fully precipitated. A slurry 1 containing 1-nitroanthraquinone was obtained.

[0056] (8) The slurry 1 containing 1-nitroanthraquinone was filtered by suction, and the filter cake was retained. The filter cake was rinsed three times with DMF to obtain a crude product 2 of 1-nitroanthraquinone, totaling 35.5 g.

[0057] (9) The crude product 2 containing 1-nitroanthraquinone and 50 g of DMF were added into a pulping kettle and stirred to mix thoroughly. The mixture was stirred at room temperature for a certain period of time to obtain a slurry 2 containing 1-nitroanthraquinone.

[0058] (10) The slurry 2 containing 1-nitroanthraquinone was filtered and the filter cake was retained. The filter cake was rinsed three times with DMF and then rinsed three times with clean water. The rinsed filter cake was then vacuum dried to obtain 18.3 g of pure 1-nitroanthraquinone with a purity of 97.9%.

[0059] Example 3: Reference Figure 1 , a continuous synthesis method of 1-nitroanthraquinone, comprising the following steps:

[0060] (1) 24 g of anthraquinone, 72 g of dichloroethane and 9.8 g of fuming nitric acid were added sequentially into a stirred reactor with heating and heat preservation functions, and stirred evenly to prepare feed liquid 1. The peristaltic pump was started and the flow rate was set to 50 mL / min, so that the feed liquid 1 flowed out of the stirred reactor and continuously flowed and circulated in the circulation system consisting of a micro mixer, a heating delay coil and a reactor, and the temperature in the micro mixer, the coil and the reactor was set to 45° C. The dispersion scale of the micro mixer was 700 μm.

[0061] (2) After the temperature of the feed liquid 1 reaches the specified temperature, the horizontal flow pump is started to pass 24 g of concentrated sulfuric acid into the mixer at a flow rate of 0.1 mL / min to mix with the feed liquid 1 to cause nitration reaction.

[0062] (3) After all the concentrated sulfuric acid was added to the circulation system, the reaction solution was allowed to circulate in the reaction system for 1 hour, and then the yield was calculated by liquid phase analysis. The yield of 1-nitroanthraquinone was 94.35% and the raw material conversion rate was 98.96%.

[0063] (4) disconnecting the circulation system, placing the feed pipe of the peristaltic pump into 1,2-dichloroethane, and pushing all the reaction solution 4 containing 1-nitroanthraquinone in the pipe into the reactor through 1,2-dichloroethane;

[0064] (5) Slowly add ammonia water into the reactor and mix thoroughly, and adjust the pH value of the reaction solution to 7. During this process, the temperature is controlled not to exceed 40°C;

[0065] (6) The reaction solution was then filtered, and the filter cake was retained. The filter cake was rinsed three times with clean water to obtain a crude product 1 containing 1-nitroanthraquinone, a total of 42 g;

[0066] (7) The crude product 1 of 1-nitroanthraquinone and 60 g of DMF were added to a recrystallization kettle and stirred to mix thoroughly. The temperature of the reactor was raised to 130° C. to dissolve all the solids. The temperature of the reactor was then slowly lowered to 30° C. for 5 h to allow 1-nitroanthraquinone to be fully precipitated. A slurry 1 containing 1-nitroanthraquinone was obtained.

[0067] (8) The slurry 1 containing 1-nitroanthraquinone was filtered by suction, and the filter cake was retained. The filter cake was rinsed three times with DMF to obtain a crude product 2 of 1-nitroanthraquinone, totaling 36 g.

[0068] (9) The crude product 2 containing 1-nitroanthraquinone and 50 g of DMF were added into a pulping kettle and stirred to mix thoroughly. The mixture was stirred at room temperature for a certain period of time to obtain a slurry 2 containing 1-nitroanthraquinone.

[0069] (10) The slurry 2 containing 1-nitroanthraquinone was filtered and the filter cake was retained. The filter cake was rinsed three times with DMF and then rinsed three times with clean water. The rinsed filter cake was then vacuum dried to obtain 18.2 g of pure 1-nitroanthraquinone with a purity of 97.9%.

[0070] Comparative Example 1: 1-nitroanthraquinone is produced intermittently using a conventional reactor, and the synthesis method thereof comprises the following steps:

[0071] (1) 24 g of anthraquinone, 72 g of 1,2-dichloroethane and 9.8 g of fuming nitric acid were added to a 250 mL reactor in sequence, and the stirring was turned on to mix the materials evenly. The temperature in the reactor was controlled at 45° C. Then, 24 g of concentrated sulfuric acid was slowly added dropwise for 5 h. After the addition of concentrated sulfuric acid was completed, the reaction was continued for 4 h. After the reaction was completed, the reaction liquid was subjected to liquid phase analysis to calculate the yield. The yield of 1-nitroanthraquinone was 85.9% and the raw material conversion rate was 94.3%.

[0072] (2) Slowly add ammonia water into the reactor and mix thoroughly, and adjust the pH value of the reaction solution to 7. During this process, the temperature is controlled not to exceed 40°C;

[0073] (3) The reaction solution was then filtered, and the filter cake was retained. The filter cake was rinsed three times with clean water to obtain a crude product 1 containing 1-nitroanthraquinone, a total of 44 g;

[0074] (4) The crude product 1 of 1-nitroanthraquinone and 60 g of DMF were added to a recrystallization kettle, stirred and mixed thoroughly, and the temperature of the reactor was raised to 130° C. to dissolve all the solids, and then the temperature of the reactor was slowly lowered to 30° C. for 5 h to allow 1-nitroanthraquinone to be fully precipitated. A slurry 1 containing 1-nitroanthraquinone was obtained.

[0075] (5) The slurry 1 containing 1-nitroanthraquinone was filtered by suction, and the filter cake was retained. The filter cake was rinsed three times with DMF to obtain a crude product 2 of 1-nitroanthraquinone, totaling 36 g.

[0076] (6) The crude product 2 containing 1-nitroanthraquinone and 50 g of DMF were added into a pulping kettle, stirred and mixed thoroughly, and stirred at room temperature for a certain period of time to obtain a slurry 2 containing 1-nitroanthraquinone.

[0077] (7) The slurry 2 containing 1-nitroanthraquinone was filtered and the filter cake was retained. The filter cake was rinsed three times with DMF and then rinsed three times with clean water. The rinsed filter cake was then vacuum dried to obtain 18.42 g of pure 1-nitroanthraquinone with a purity of 96.9%.

[0078] Comparative Example 1 adopts a kettle process for nitration reaction. Due to the poor heat exchange effect of the reactor, concentrated sulfuric acid needs to be slowly added dropwise, the reaction time is slow, the addition and reaction time exceed 9 hours in total, and the liquid phase yield of 1-nitroanthraquinone does not exceed 90%. By adopting the micro-reaction continuous synthesis process, not only the reaction time can be shortened to less than 3 hours, the product yield can reach more than 90%, and the selectivity of the synthesis of the target product is better.

[0079] Comparative Example 2: 1-nitroanthraquinone is produced using sulfuric acid as a reaction solvent, and the synthesis method thereof comprises the following steps:

[0080] (1) 24 g of anthraquinone was dissolved in 92 g of concentrated sulfuric acid to prepare feed solution 1 (anthraquinone was completely dissolved, feed solution 1 was a solution), and 9.0 g of fuming nitric acid and 92 g of concentrated sulfuric acid were mixed to prepare feed solution 2.

[0081] (1) Start pump 1 and pump 2, so that both feed liquid 1 and feed liquid 2 are passed into the T-shaped mixer at a flow rate of 2 mL / min, mixed evenly and nitration reaction occurs, and the mixed materials are passed into the heating delay coil to continue the reaction so that the raw material conversion is complete. The temperature of the micro mixer and the heating delay coil is 35°C, and the retention time of the reaction liquid in the delay coil is 10 minutes. The reaction liquid is collected in the reactor and the liquid phase analysis of the reaction liquid is performed. The yield of 1-nitroanthraquinone is 55% and the raw material conversion rate is 98%.

[0082] (2) After the collection is completed, slowly add ammonia water into the reactor and mix thoroughly, and adjust the pH value of the reaction solution to 7. During this process, the temperature is controlled not to exceed 40° C.;

[0083] (3) The reaction solution was then filtered, and the filter cake was retained. The filter cake was rinsed three times with clean water to obtain a crude product 1 containing 1-nitroanthraquinone, a total of 41 g;

[0084] (4) The crude product 1 of 1-nitroanthraquinone and 60 g of DMF were added to a recrystallization kettle, stirred and mixed thoroughly, and the temperature of the reactor was raised to 130° C. to dissolve all the solids, and then the temperature of the reactor was slowly lowered to 30° C. for 5 h to allow 1-nitroanthraquinone to be fully precipitated. A slurry 1 containing 1-nitroanthraquinone was obtained.

[0085] (5) The slurry 1 containing 1-nitroanthraquinone was filtered by suction, and the filter cake was retained. The filter cake was rinsed three times with DMF to obtain a crude product 2 of 1-nitroanthraquinone, totaling 33 g.

[0086] (6) The crude product 2 containing 1-nitroanthraquinone and 50 g of DMF were added into a pulping kettle, stirred and mixed thoroughly, and stirred at room temperature for a certain period of time to obtain a slurry 2 containing 1-nitroanthraquinone.

[0087] (7) The slurry 2 containing 1-nitroanthraquinone was filtered and the filter cake was retained. The filter cake was rinsed three times with DMF and then rinsed three times with clean water. The rinsed filter cake was then vacuum dried to obtain 19.4 g of pure 1-nitroanthraquinone with a purity of 66.9%.

[0088] Comparative Example 3: Reference Figure 1 , a continuous synthesis method of 1-nitroanthraquinone, greatly increasing the feed rate of sulfuric acid, comprising the following steps:

[0089] (1) 24 g of anthraquinone, 48 g of dichloroethane and 9 g of fuming nitric acid were added to a stirred reactor with heating and heat preservation functions in sequence and stirred to prepare liquid 1. The peristaltic pump was started and the flow rate was set to 35 mL / min, so that liquid 1 flowed out of the stirred reactor and continuously circulated in the circulation system consisting of a micro mixer, a heating delay coil and a reactor, and the temperature in the micro mixer, the coil and the reactor was set to 35° C. The dispersion scale of the micro mixer was 500 μm.

[0090] (2) After the temperature of the feed liquid 1 reaches the specified temperature, the horizontal flow pump is started to pass 18.4 g of concentrated sulfuric acid into the mixer at a flow rate of 10 mL / min to mix with the feed liquid 1 to cause nitration reaction.

[0091] (3) After all 18.4 g of concentrated sulfuric acid was added to the circulation system, the reaction solution was allowed to circulate in the reaction system for 2 h, and then the yield was calculated by liquid phase analysis. The yield of 1-nitroanthraquinone was 69.3% and the conversion rate of anthraquinone was 98.3%.

[0092] (4) disconnecting the circulation system, placing the feed pipe of the peristaltic pump into 1,2-dichloroethane, and pushing all the reaction solution 4 containing 1-nitroanthraquinone in the pipe into the reactor through 1,2-dichloroethane;

[0093] (5) Slowly add ammonia water into the reactor and mix thoroughly, and adjust the pH value of the reaction solution to 6.5. During this process, the temperature is controlled not to exceed 40°C;

[0094] (6) The reaction solution was then filtered, and the filter cake was retained. The filter cake was rinsed three times with clean water to obtain a crude product 1 containing 1-nitroanthraquinone, a total of 39.6 g;

[0095] (7) The crude product 1 of 1-nitroanthraquinone and 60 g of DMF were added to a reactor and stirred to mix thoroughly. The temperature of the reactor was raised to 130° C. to dissolve all the solids. The temperature of the reactor was then slowly lowered to 30° C. at a cooling rate of 0.3° C. / min to allow 1-nitroanthraquinone to be fully precipitated. A slurry 1 containing 1-nitroanthraquinone was obtained.

[0096] (8) The slurry 1 containing 1-nitroanthraquinone was filtered and the filter cake was retained. The filter cake was rinsed three times with DMF to obtain a crude product 2 of 1-nitroanthraquinone, totaling 34.9 g.

[0097] (9) The crude product 2 containing 1-nitroanthraquinone and 50 g of DMF were added into a reaction kettle and stirred to mix thoroughly. The mixture was stirred at room temperature for a certain period of time to obtain a slurry 2 containing 1-nitroanthraquinone.

[0098] (10) The slurry 2 containing 1-nitroanthraquinone was filtered and the filter cake was retained. The filter cake was rinsed three times with DMF and then rinsed three times with clean water. The rinsed filter cake was then vacuum dried to obtain 14.86 g of pure 1-nitroanthraquinone with a purity of 93.9%.

[0099] The above-mentioned embodiments only express several implementation methods of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. For ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A method for continuously synthesizing 1-nitroanthraquinone, characterized in that: The steps include: (1) mixing raw materials anthraquinone, 1,2-dichloroethane and fuming nitric acid uniformly to form a slurry solution; and using concentrated sulfuric acid as a second feed liquid; (2) adding the slurry solution into a stirred reactor with heating and heat preservation functions, starting a peristaltic pump to allow the slurry solution to flow out of the stirred reactor, and continuously flowing and circulating in a circulation system consisting of a micro mixer, a heating delay coil, and a stirred reactor; (3) The second liquid feed is transported to the micro mixer by a horizontal flow pump, and mixed with the circulating slurry solution to undergo a nitration reaction to obtain a mixed material; wherein the feed flow rate ratio of the second liquid feed to the flow rate of the material in the circulation system is 1:(140-500); the mixed material continues to flow through the heating delay coil and the stirred reactor, and is mixed with concentrated sulfuric acid again when it flows through the micro mixer next time, and this cycle is repeated until all the required concentrated sulfuric acid is pumped into the mixed material, and then the operation of the horizontal flow pump is stopped; (4) continuing to circulate the mixed material between the stirred reactor, the micro-mixer and the heating delay coil for a period of time to allow the raw materials to fully react to obtain a reaction solution containing 1-nitroanthraquinone; (5) disconnecting the circulation system, placing the feed pipe of the peristaltic pump into 1,2-dichloroethane, and pushing all the reaction liquid containing 1-nitroanthraquinone in the pipe into the reactor through 1,2-dichloroethane; (6) adding aqueous ammonia to the reaction solution containing 1-nitroanthraquinone and mixing thoroughly, adjusting the pH value of the reaction solution to 6-7, and controlling the temperature in this process not to exceed 40° C.; (7) The reaction solution after pH adjustment is post-treated to obtain a pure product of 1-nitroanthraquinone.

2. The continuous synthesis method of 1-nitroanthraquinone according to claim 1, characterized in that: In step (1), the mass ratio of anthraquinone to fuming nitric acid is 1:(0.3-0.4), and the mass ratio of anthraquinone to 1,2-dichloroethane is 1:(1-3).

3. The continuous synthesis method of 1-nitroanthraquinone according to claim 1, characterized in that: In step (2), the flow rate of the slurry solution is 20-50 mL / min; in step (3), the flow rate of the second liquid is 0.1-5 mL / min.

4. The continuous synthesis method of 1-nitroanthraquinone according to claim 1, characterized in that: In step (2), the micro mixer is a T-type micro mixer, and the dispersion scale of the micro mixer is 250-750 μm; the temperature of the mixer, the heating delay coil and the reactor is kept consistent, and the temperature range is 25-45°C.

5. The method for continuous synthesis of 1-nitroanthraquinone according to claim 1, characterized in that: In step (2), the volume ratio of the circulating material in the delay coil and the reactor is (5-3):

1.

6. The method for continuous synthesis of 1-nitroanthraquinone according to claim 1, characterized in that: In step (4), the cycle time of continuing to circulate for a period of time is 1-4 hours.

7. The method for continuous synthesis of 1-nitroanthraquinone according to claim 1, characterized in that: The step (7) comprises: 7.1) filtering the reaction solution containing 1-nitroanthraquinone, retaining the filter cake, and rinsing the filter cake with clean water to obtain a first crude product containing 1-nitroanthraquinone; 7.2) The first crude product of 1-nitroanthraquinone is fully mixed with DMF, and the temperature of the mixed solution is raised to 130° C. to dissolve all the solids, and then the temperature is slowly lowered to 30° C. to allow 1-nitroanthraquinone to be fully precipitated; thereby obtaining a first slurry containing 1-nitroanthraquinone; 7.3) filtering the slurry containing 1-nitroanthraquinone by suction, retaining the filter cake, and rinsing the filter cake with DMF to obtain a second crude product of 1-nitroanthraquinone; 7.4) adding the second crude product containing 1-nitroanthraquinone and DMF, mixing them thoroughly, and stirring at room temperature to obtain a second slurry containing 1-nitroanthraquinone; 7.5) The second slurry containing 1-nitroanthraquinone is filtered, and the filter cake is retained. The filter cake is rinsed with DMF and then with clean water, and the rinsed filter cake is vacuum dried to obtain pure 1-nitroanthraquinone.

8. The method for continuous synthesis of 1-nitroanthraquinone according to claim 1, characterized in that: In step 7.2) and step 7.4), the amount of DMF used is 1-3 times the quality of the corresponding crude product.

9. The method for continuous synthesis of 1-nitroanthraquinone according to claim 1, characterized in that: In step 7.2), the cooling rate of the cooling process is 0.3-0.8°C / min.

10. The method for continuous synthesis of 1-nitroanthraquinone according to claim 1, characterized in that: In step 7.4), the stirring time is 3-8 hours; in step 7.5), the vacuum drying temperature is 50-70°C.

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