Continuous production system and process of n-cyanoethyl-n-acetoxyaniline

Abstract

The application discloses a kind of N-cyanoethyl-N-acetoxyethyl aniline continuous production system and process, liquid N-cyanoethyl aniline with water content not more than 1wt% is mixed with catalyst, ethylene oxide is continuously fed to hydroxylation reaction unit and is generated N-cyanoethyl-N-hydroxyethyl aniline finished product after hydroxylation reaction, and ethylene oxide can be selectively supplemented in hydroxylation reaction unit;N-cyanoethyl-N-hydroxyethyl aniline finished product is continuously fed with acetic anhydride to esterification reaction unit and is obtained N-cyanoethyl-N-acetoxyethyl aniline solution after esterification reaction;N-cyanoethyl-N-acetoxyethyl aniline finished product is separated from N-cyanoethyl-N-acetoxyethyl aniline solution and acetic acid is recovered using acetic acid recovery unit.The application is successfully integrated by pre-dehydration of N-cyanoethyl aniline Hydroxylation, esterification two processes are continuous, and then production efficiency is improved, and raw material cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of N-cyanoethyl-N-acetoxyethyl aniline production technology, specifically to a continuous production system and process for N-cyanoethyl-N-acetoxyethyl aniline. Background Technology

[0002] N-Cyanoethyl-N-acetoxyethylaniline is a commonly used dye intermediate in the synthesis of disperse dyes. As a coupling component, it can be used to synthesize CI Disperse Orange 30, CI Disperse Orange 31, CI Disperse Red 35, CI Disperse Red 72, CI Disperse Red 136, CI Disperse Red 177 and CI Disperse Brown 9, etc., and has a wide range of applications.

[0003] Currently, there are many publicly disclosed methods for synthesizing N-cyanoethyl-N-acetoxyethyl aniline. Chinese patent application CN106117073A discloses a synthesis method that uses a hydroxyl group to react with acetic acid at a temperature of 110–140°C. Furthermore, a molecular sieve is added in the later stages of the reaction to ensure complete reaction and allow for resource reuse. However, this method increases the synthesis cost due to the use of a molecular sieve, and the sieve requires activation after use, complicating the synthesis process.

[0004] In their paper "Synthesis of Dye Intermediate N-Cyanoethyl-N-acetoxyethylaniline," Zheng Jing et al. used glacial acetic acid as an acylating agent. The product N-cyanoethyl-N-acetoxyethylaniline was obtained by reacting it with the raw material N-hydroxyethyl-N-cyanoethylaniline at a molar ratio of 3:1 via atmospheric distillation at 140°C for 8 hours. This method has a relatively long reaction time.

[0005] To address the issues of cumbersome synthesis steps and long reaction times mentioned above, patent application CN113444019A provides a method for preparing N-cyanoethyl-N-acetoxyethyl aniline, comprising the following steps: Step 1), reacting N-cyanoethyl aniline with ethylene oxide via hydroxylation to obtain the hydroxylated product N-hydroxyethyl-N-cyanoethyl aniline; Step 2), reacting the hydroxylated product N-hydroxyethyl-N-cyanoethyl aniline with acetic anhydride and / or acetic acid via esterification to obtain the esterified product. However, this method is a batch production process, with the epoxide introduced intermittently. Furthermore, before acetic anhydride esterification, the temperature needs to be raised to 100–140°C for dehydration of the hydroxylated product and the addition of acetic acid. Because the hydroxylated product contains a hydrophilic -OH group, the dehydration process often requires high temperatures and long times; otherwise, the hydroxylated product will contain a lot of water, leading to the consumption of more acetic anhydride during subsequent acetic anhydride esterification due to hydrolysis. In the above-mentioned patented technical solution, the mass ratio of hydroxylated N-cyanoethyl-N-hydroxyethyl aniline to acetic anhydride is 1.1 to 1.5:1, which is equivalent to a molar ratio of N-cyanoethyl-N-hydroxyethyl aniline to acetic anhydride of approximately 1:1.25 to 1.7.

[0006] The above processes are all intermittent production processes. Therefore, researching a continuous production system and process for N-cyanoethyl-N-acetoxyethyl aniline that improves production efficiency, reduces raw material consumption, and shortens production time has become an urgent technical problem to be solved. Summary of the Invention

[0007] To address the aforementioned technical problems and shortcomings in the field, this invention provides a continuous production system and process for N-cyanoethyl-N-acetoxyethyl aniline, which is easy to operate. By pre-dehydrating N-cyanoethyl aniline, the hydroxylation and esterification processes can be integrated continuously, thereby improving production efficiency and reducing raw material costs. Ethylene oxide can be continuously and stably fed through a pump, which improves the safety and stability of production compared to intermittent feeding methods.

[0008] This invention allows for the dehydration of N-cyanoethyl aniline before its use, reducing the amount of acetic anhydride used in the esterification reaction by 9%–10% compared to existing processes. The hydroxylation reaction can utilize a combination of jet reactors and spray circulation to enhance mass transfer between reactants and shorten reaction time. This invention also employs a series tubular reactor, ensuring sufficient residence time while reducing backmixing. Furthermore, this invention introduces a thin-film evaporator into the esterification process, which, compared to traditional batch distillation, offers higher heat transfer efficiency and faster evaporation rates, not only improving the efficiency of acetic acid recovery and reducing energy consumption but also facilitating continuous production.

[0009] A continuous production system for N-cyanoethyl-N-acetoxyethyl aniline includes a dehydration unit, a hydroxylation reaction unit, an esterification reaction unit, and an acetic acid recovery unit connected in sequence.

[0010] The dehydration unit is used for the dehydration of N-cyanoethyl aniline;

[0011] The hydroxylation reaction unit is used to react ethylene oxide with dehydrated N-cyanoethyl aniline to produce the N-cyanoethyl-N-hydroxyethyl aniline product.

[0012] The esterification reaction unit is used to esterify N-cyanoethyl-N-hydroxyethyl aniline product with acetic anhydride to generate N-cyanoethyl-N-acetoxyethyl aniline solution;

[0013] The acetic acid recovery unit is used to separate the N-cyanoethyl-N-acetoxyethyl aniline product from the N-cyanoethyl-N-acetoxyethyl aniline solution and recover the acetic acid.

[0014] In one embodiment, the dehydration unit may include a vacuum pump, a water recovery tank, a first cooler, and a dehydration vessel connected in sequence, with the dehydration vessel connected to the hydroxylation reaction unit.

[0015] A jet reactor can be installed between the dehydration unit and the hydroxylation reaction unit. The jet reactor is used to continuously receive the mixed ethylene oxide and the dehydrated N-cyanoethyl aniline and continuously jet out the ethylene oxide / N-cyanoethyl aniline mixture.

[0016] The hydroxylation reaction unit may include a receiving vessel with a circulation pipeline, which may be connected to a spray pipe at the top of the receiving vessel. The spray pipe may be a coil structure, with 2-3 mm holes.

[0017] The jet outlet of the jet reactor can be connected to an insertion tube, and the other end of the insertion tube can be connected to a distributor located near the bottom inside the receiving vessel. The height of the other end of the insertion tube from the bottom of the receiving vessel can be 1 / 4 to 1 / 3 of the total height of the receiving vessel.

[0018] The hydroxylation reaction unit may also include a multi-stage tubular reactor with circulation lines, located between the receiving vessel and the esterification reaction unit. The first-stage tubular reactor connected to the receiving vessel may be equipped with an ethylene oxide replenishment port. The tubular reactor can be temperature-controlled via a jacket. In a multi-stage tubular reactor, overflow can be transferred from one stage to the next via an overflow line. A total of 2 to 4 stages of tubular reactors can be configured.

[0019] An N-hydroxyethyl-N-cyanoethyl aniline product reactor can be set up between the hydroxylation reaction unit and the esterification reaction unit. The N-hydroxyethyl-N-cyanoethyl aniline product reactor is used to buffer the N-hydroxyethyl-N-cyanoethyl aniline product generated in the hydroxylation reaction unit and to transport the N-hydroxyethyl-N-cyanoethyl aniline product to the esterification reaction unit.

[0020] The esterification reaction unit may include interconnected pipe mixers and esterification reactors.

[0021] The pipeline mixer is used to continuously receive and mix N-cyanoethyl-N-hydroxyethyl aniline product and acetic anhydride and then transport the N-cyanoethyl-N-hydroxyethyl aniline product / acetic anhydride mixture to the esterification reactor.

[0022] The esterification reactor can be designed as a horizontal vessel, divided into four chambers by partitions, each equipped with a stirring and temperature control device.

[0023] The acetic acid recovery unit includes a heat exchanger, an evaporator, a vapor-liquid separator, a secondary cooler, an acetic acid collection tank, and an N-cyanoethyl-N-acetoxyethyl aniline finished product tank.

[0024] The first inlet of the heat exchanger is connected to the esterification reaction unit. The first outlet of the heat exchanger, which is connected to the first inlet, is connected to the inlet of the evaporator. The finished product outlet of the evaporator is connected to the N-cyanoethyl-N-acetoxyethyl aniline finished product tank. The steam outlet of the evaporator is connected to the second inlet of the heat exchanger. The second outlet of the heat exchanger, which is connected to the second inlet, is connected to the gas-liquid separator. The gas outlet of the gas-liquid separator is connected to the acetic acid collection tank through the second cooler. The liquid outlet of the gas-liquid separator is connected to the acetic acid collection tank. The acetic acid collection tank is connected to the vacuum equipment.

[0025] A continuous production process for N-cyanoethyl-N-acetoxyethyl aniline includes:

[0026] Liquid N-cyanoethyl aniline with a water content of no more than 1 wt% is mixed with a catalyst and ethylene oxide and continuously fed into a hydroxylation reaction unit to produce N-cyanoethyl-N-hydroxyethyl aniline product. Ethyl oxide can be selectively added to the hydroxylation reaction unit.

[0027] N-cyanoethyl-N-hydroxyethyl aniline product and acetic anhydride are continuously fed into the esterification reaction unit to carry out the esterification reaction to obtain N-cyanoethyl-N-acetoxyethyl aniline solution;

[0028] The N-cyanoethyl-N-acetoxyethyl aniline product was separated from the N-cyanoethyl-N-acetoxyethyl aniline solution and the acetic acid was recovered using an acetic acid recovery unit.

[0029] In one embodiment, the continuous production process of N-cyanoethyl-N-acetoxyethyl aniline uses the aforementioned continuous production system for N-cyanoethyl-N-acetoxyethyl aniline, which can utilize a dehydration unit to dehydrate liquid N-cyanoethyl aniline to a water content of no more than 1 wt%.

[0030] In one embodiment, the liquid N-cyanoethyl aniline with a water content of no more than 1 wt% can also be liquid N-cyanoethyl aniline that has been dehydrated during the N-cyanoethyl aniline production process.

[0031] Furthermore, the water content of the liquid N-cyanoethyl aniline does not exceed 0.5 wt%.

[0032] The catalyst can be acetic acid, and the amount used can be 2% to 5% of the mass of N-cyanoethyl aniline.

[0033] The molar ratio of ethylene oxide to N-cyanoethyl aniline can be 0.65 to 1.45:1, preferably 1.05:1. If ethylene oxide is added in stages, the molar ratio of ethylene oxide to N-cyanoethyl aniline added in the first stage (e.g., at the inlet of the jet reactor) can be 0.5 to 0.9:1, and the molar ratio of ethylene oxide to N-cyanoethyl aniline added in the second stage (e.g., at the ethylene oxide replenishment port of the first-stage tubular reactor connected to the receiving vessel) can be 0.15 to 0.55:1.

[0034] The temperature of the hydroxylation reaction unit can be controlled between 50 and 90°C. Furthermore, the temperature of the jet reactor and receiving vessel can be controlled between 50 and 80°C, and the temperature of the tubular reactor can be controlled between 80 and 90°C.

[0035] The residence time of materials in the hydroxylation reaction unit can be 60–120 min. Furthermore, the residence time of materials in the receiving vessel can be 30–60 min, and the residence time of materials in the tubular reactor can be 30–60 min.

[0036] The material circulation rate of the hydroxylation reaction unit (e.g., receiving vessel, tubular reactor) can be 10 to 20 times the feed flow rate.

[0037] The molar ratio of N-cyanoethyl-N-hydroxyethyl aniline to acetic anhydride can be 1:1.05 to 1.15.

[0038] The reaction temperature of the esterification reaction unit can be controlled between 80 and 100°C. The residence time of the materials in the esterification reaction unit can be between 60 and 120 minutes.

[0039] In one embodiment, the acetic acid recovery unit recovers acetic acid to an N-cyanoethyl-N-acetoxyethyl aniline solution with a solid content of 75% to 92%, and further to a solid content of 85% to 90%.

[0040] The acetic acid recovered by this invention can be used in the synthesis of m-aminoacetanilide, 167 esterification solution, etc.

[0041] The evaporator may be a thin-film evaporator.

[0042] Compared with the prior art, the beneficial effects of this invention are as follows:

[0043] 1. This invention successfully integrates the hydroxylation and esterification processes into a continuous whole by first pre-treating N-cyanoethyl aniline with dehydration or by using N-cyanoethyl aniline liquid with low water content, which greatly improves production efficiency and reduces raw material costs; ethylene oxide is continuously and stably fed through a pump, which improves the safety and stability of production compared to intermittent feeding methods.

[0044] 2. Through this invention, N-cyanoethyl aniline is first dehydrated or a liquid N-cyanoethyl aniline with low water content is used. Since there is no intermolecular force between N-cyanoethyl aniline and water (no hydroxyl group), the dehydration temperature is lower and the time is shorter, thus saving the time and energy required for high-temperature and long-term dehydration of N-hydroxyethyl-N-cyanoethyl aniline. The resulting N-hydroxyethyl-N-cyanoethyl aniline can be directly used for esterification, while avoiding the problem of increased acetic anhydride usage and reduced reaction rate in the esterification process due to incomplete dehydration of N-hydroxyethyl-N-cyanoethyl aniline. The amount of acetic anhydride used can be reduced by 9% to 10% compared with the existing process.

[0045] 3. Through this invention, the hydroxylation reaction adopts a combination of jet reactor and spray circulation, which enhances the mass transfer between reactants and shortens the reaction time; through the series tubular reactor, the residence time is guaranteed while reducing the backmixing of materials.

[0046] 4. The esterification process incorporates a thin-film evaporator, which, compared to traditional batch distillation, offers higher heat transfer efficiency and faster evaporation speed. This not only improves the efficiency of acetic acid recovery and reduces energy consumption but also facilitates continuous operation. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the continuous production system for N-cyanoethyl-N-acetoxyethyl aniline, as shown in the example. Detailed Implementation

[0048] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0049] Unless otherwise specified, the operating methods in the following examples are generally performed under conventional conditions or as recommended by the manufacturer.

[0050] like Figure 1As shown, this embodiment of a continuous production system for N-cyanoethyl-N-acetoxyethyl aniline includes, in sequence, a vacuum pump (not shown), a recovery water tank V1, a first cooler E1, a dehydration vessel R1, a first feed pump P1, a jet reactor R2, a receiving vessel R3, a third feed pump P3, a first-stage tubular reactor R4, a fourth feed pump P4, a second-stage tubular reactor R5, a fifth feed pump P5, and an N-hydroxyethyl-N-cyanoethyl aniline finished product vessel R6. The sixth feed pump P5, the pipeline mixer d, the esterification reactor R7, the eighth feed pump P8, and the heat exchanger E2 are connected. The heat exchanger E2 is connected to the thin film evaporator A and the gas-liquid separator V3. The thin film evaporator A is connected to the N-cyanoethyl-N-acetoxyethyl aniline finished product tank V2. The gas outlet of the gas-liquid separator V3 is connected to the acetic acid collection tank V4 through the second cooler E3. The liquid outlet of the gas-liquid separator V3 is connected to the acetic acid collection tank V4. The acetic acid collection tank V4 is connected to the vacuum equipment (not shown).

[0051] Under vacuum, N-cyanoethyl aniline in dehydration vessel R1 undergoes reduced-pressure dehydration. The dehydrated water is cooled by the first cooler E1 and collected in the recovery water tank V1. The dehydrated N-cyanoethyl aniline, under the action of the first feed pump P1, is mixed with the catalyst acetic acid and then enters the jet reactor R2. The jet reactor R2 is also connected to a second feed pump P2, which continuously feeds ethylene oxide into the jet reactor R2. After the dehydrated N-cyanoethyl aniline, acetic acid, and ethylene oxide are mixed evenly in the jet reactor R2, the mixture is jetted out. The jet outlet of the jet reactor R2 is connected to the insertion pipe a, and the other end of the insertion pipe a is connected to a distributor located near the bottom of the receiving vessel R3. The distance between the other end of the insertion pipe a and the bottom of the receiving vessel R3 can be 1 / 4 to 1 / 3 of the total height of the receiving vessel R3.

[0052] The receiving vessel R3 has a first circulation pipeline, and the third feeding pump P3 is installed on the first circulation pipeline. One end of the circulation pipeline is connected to the top spray pipe b inside the receiving vessel R3. The spray pipe b can be a coil structure, and 2-3 mm holes can be opened on the coil.

[0053] The first-stage tubular reactor R4 is equipped with a second circulation line, and the fourth feed pump P4 is located on the second circulation line. An ethylene oxide replenishment port may also be provided at the inlet of the first-stage tubular reactor R4.

[0054] The second-stage tubular reactor R5 is equipped with a third circulation pipeline, and the fifth feed pump P5 is located on the third circulation pipeline.

[0055] In receiving reactor R3, first-stage tubular reactor R4, and second-stage tubular reactor R5, the dehydrated N-cyanoethyl aniline undergoes a hydroxylation reaction with acetic acid and ethylene oxide to produce N-cyanoethyl-N-hydroxyethyl aniline product, which is then fed into N-cyanoethyl-N-hydroxyethyl aniline product reactor R6 by the action of the corresponding feed pump.

[0056] Under the action of the sixth feed pump P6, the N-cyanoethyl-N-hydroxyethyl aniline product in the N-cyanoethyl-N-hydroxyethyl aniline product reactor R6 is conveyed to the pipeline mixer d. The pipeline mixer d is also connected to the seventh feed pump P7, which is used to continuously feed acid anhydride to the pipeline mixer d. After the N-cyanoethyl-N-hydroxyethyl aniline product and acid anhydride are mixed in the pipeline mixer d, they enter the esterification reactor R7. The esterification reactor R7 can be designed as a horizontal reactor, divided into 4 chambers by partitions, each chamber is equipped with a stirring and temperature control device. The N-cyanoethyl-N-hydroxyethyl aniline product and acid anhydride undergo an esterification reaction in the esterification reactor R7 to generate an N-cyanoethyl-N-acetoxyethyl aniline solution, which is discharged through the eighth feed pump P8.

[0057] The N-cyanoethyl-N-acetoxyethyl aniline solution from the eighth feed pump P8 enters the heat exchanger E2 through the first inlet. After preheating, it leaves the heat exchanger E2 through the first outlet and enters the thin-film evaporator A for evaporation and concentration. The concentrated N-cyanoethyl-N-acetoxyethyl aniline leaves the thin-film evaporator A through the finished product outlet and enters the N-cyanoethyl-N-acetoxyethyl aniline finished product tank V2. The generated steam leaves the thin-film evaporator A through the steam outlet and enters the heat exchanger E2 through the second inlet to preheat the N-cyanoethyl-N-acetoxyethyl aniline solution from the eighth feed pump P8. After cooling down, it leaves the heat exchanger E2 through the second outlet and enters the gas-liquid separator V3.

[0058] The above-mentioned continuous production system for N-cyanoethyl-N-acetoxyethyl aniline is used to carry out the continuous production process of N-cyanoethyl-N-acetoxyethyl aniline:

[0059] Liquid N-cyanoethyl aniline with a water content of 9 wt% was dehydrated under reduced pressure to a water content of 0.5 wt%. The dehydrated N-cyanoethyl aniline was continuously discharged and mixed with acetic acid at a mass ratio of 5% N-cyanoethyl aniline. This mixture was then continuously fed with ethylene oxide at a molar ratio of ethylene oxide to N-cyanoethyl aniline of 0.9:1 into jet reactor R2 for hydroxylation. The temperature of jet reactor R2 was controlled at 65–70°C. The discharge from jet reactor R2 was transferred to receiving vessel R3. The hydroxylated N-cyanoethyl-N-hydroxyethyl aniline in receiving vessel R3 was recycled at a rate of 10 times the total feed volume. Simultaneously, the hydroxylated N-cyanoethyl-N-hydroxyethyl aniline was continuously discharged from receiving vessel R3 and mixed with ethylene oxide at a molar ratio of ethylene oxide to N-cyanoethyl aniline of 0.15:1, and fed into the first-stage tubular reactor R4. The reaction temperature in receiving vessel R3 was 75–70°C. The temperature is 80℃, and the residence time is controlled at 30 min. The first-stage tubular reactor R4 circulates at 10 times the total feed volume, while simultaneously discharging the same amount of raw material continuously to the second-stage tubular reactor R5. The temperature of the first-stage tubular reactor R4 is controlled at 80-85℃. The second-stage tubular reactor circulates at 10 times the total feed volume, while simultaneously discharging the same amount of raw material continuously to the N-cyanoethyl-N-hydroxyethylaniline product reactor R6 to obtain the N-cyanoethyl-N-hydroxyethylaniline product. The temperature of the second-stage tubular reactor is controlled at 80-85℃. The total residence time of the material in the first-stage tubular reactor R4 and the second-stage tubular reactor R5 is 60 min.

[0060] The N-cyanoethyl-N-hydroxyethyl aniline product and acetic anhydride are continuously fed into the pipeline mixer d at a molar ratio of 1:1.15. The mixture is then discharged into the horizontal esterification reactor R7 for further esterification to obtain an N-cyanoethyl-N-acetoxyethyl aniline solution. The reaction temperature in the horizontal esterification reactor R7 is controlled at 95-100℃, and the residence time is controlled at 80 min.

[0061] The N-cyanoethyl-N-acetoxyethylaniline solution produced by the horizontal esterification reactor R7 is preheated by heat exchanger E2 and then discharged to scraped film evaporator A. Under vacuum, the acetic acid vapor from scraped film evaporator A is heated by heat exchanger E2, and a small amount of condensate is discharged to gas-liquid separator V3. The gas from gas-liquid separator V3 is cooled by cooler E3 to recover acetic acid. The bottom discharge from film evaporator A is the finished N-cyanoethyl-N-acetoxyethylaniline product, with a solid content of 90% and an HPLC purity of 94.5%.

[0062] Comparative Example 1

[0063] The N-cyanoethyl-N-acetoxyethyl aniline continuous production system described in the above embodiment is used to perform a similar continuous production process for N-cyanoethyl-N-acetoxyethyl aniline. The difference is that the liquid N-cyanoethyl aniline with a water content of 9 wt% is not dehydrated. The finished N-cyanoethyl-N-hydroxyethyl aniline and acetic anhydride are continuously fed into the pipeline mixer d at a molar ratio of 1:1.5. All other aspects remain the same. The N-cyanoethyl-N-acetoxyethyl aniline finished product, with a solid content of 90% and an HPLC purity of 88.2%, is discharged from the bottom of the thin-film evaporator A.

[0064] Comparative Example 2

[0065] Intermittent production process is adopted.

[0066] Step 1: In the pulping kettle, liquid N-cyanoethyl aniline with a water content of 9wt% is mixed with 10% acetic acid by its mass and pulped at 80-85℃. Then, ethylene oxide is introduced over 4 hours at a molar ratio of ethylene oxide to N-cyanoethyl aniline of 1.08:1. After the introduction is completed, the temperature is maintained for another 4 hours.

[0067] Step Two: The N-cyanoethyl-N-hydroxyethylaniline produced in Step One is subjected to vacuum dehydration at a temperature controlled between 110 and 130°C for 5 hours. After dehydration, the water content of the N-cyanoethyl-N-hydroxyethylaniline is measured to be 3.75%. Subsequently, acetic anhydride is added dropwise to the esterification reactor at a molar ratio of N-cyanoethyl-N-hydroxyethylaniline to acetic anhydride of 1:1.35 over 4 hours, with the reaction temperature controlled between 90 and 105°C. After the addition is complete, the reaction is maintained at this temperature for another 4 hours.

[0068] Step 3: After the reaction in Step 2 is completed, the esterification solution is heated to 140℃ under vacuum to recover acetic acid. After 6 hours of recovery, N-cyanoethyl-N-acetoxyethyl aniline product with a solid content of 90% and an HPLC purity of 90.25% is obtained.

[0069] Furthermore, it should be understood that after reading the above description of the present invention, those skilled in the art can make various alterations or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A continuous production system for N-cyanoethyl-N-acetoxyethyl aniline, characterized in that, It includes a dehydration unit, a hydroxylation reaction unit, an esterification reaction unit, and an acetic acid recovery unit connected in sequence; The dehydration unit is used for the dehydration of N-cyanoethyl aniline; The hydroxylation reaction unit is used to react ethylene oxide with dehydrated N-cyanoethyl aniline to produce the N-cyanoethyl-N-hydroxyethyl aniline product. The esterification reaction unit is used to esterify N-cyanoethyl-N-hydroxyethyl aniline product with acetic anhydride to generate N-cyanoethyl-N-acetoxyethyl aniline solution; The acetic acid recovery unit is used to separate the N-cyanoethyl-N-acetoxyethyl aniline product from the N-cyanoethyl-N-acetoxyethyl aniline solution and recover the acetic acid.

2. The continuous production system for N-cyanoethyl-N-acetoxyethyl aniline according to claim 1, characterized in that, The dehydration unit includes a vacuum pump, a water recovery tank, a first cooler, and a dehydration kettle connected in sequence. The dehydration kettle is connected to the hydroxylation reaction unit.

3. The continuous production system for N-cyanoethyl-N-acetoxyethyl aniline according to claim 1, characterized in that, A jet reactor is installed between the dehydration unit and the hydroxylation reaction unit; The hydroxylation reaction unit includes a receiving vessel with a circulation pipeline connected to a top spray pipe inside the receiving vessel; The jet reactor is used to continuously receive mixed ethylene oxide and dehydrated N-cyanoethyl aniline and continuously jet out the ethylene oxide / N-cyanoethyl aniline mixture; the jet outlet of the jet reactor is connected to an insertion tube, and the other end of the insertion tube is connected to a distributor located near the bottom of the receiving vessel.

4. The continuous production system for N-cyanoethyl-N-acetoxyethyl aniline according to claim 3, characterized in that, The hydroxylation reaction unit also includes a multi-stage tubular reactor with circulation pipelines located between the receiving vessel and the esterification reaction unit; The first-stage tubular reactor connected to the receiving vessel is equipped with an ethylene oxide replenishment port.

5. The continuous production system for N-cyanoethyl-N-acetoxyethyl aniline according to claim 1, characterized in that, An N-hydroxyethyl-N-cyanoethyl aniline product reactor is set between the hydroxylation reaction unit and the esterification reaction unit. The N-hydroxyethyl-N-cyanoethyl aniline product reactor is used to buffer the N-hydroxyethyl-N-cyanoethyl aniline product generated in the hydroxylation reaction unit and to transport the N-hydroxyethyl-N-cyanoethyl aniline product to the esterification reaction unit.

6. The continuous production system for N-cyanoethyl-N-acetoxyethyl aniline according to claim 1, characterized in that, The esterification reaction unit includes an interconnected pipe mixer and an esterification reactor; The pipeline mixer is used to continuously receive and mix N-cyanoethyl-N-hydroxyethyl aniline product and acetic anhydride and then transport the N-cyanoethyl-N-hydroxyethyl aniline product / acetic anhydride mixture to the esterification reactor.

7. The continuous production system for N-cyanoethyl-N-acetoxyethyl aniline according to claim 1, characterized in that, The acetic acid recovery unit includes a heat exchanger, an evaporator, a vapor-liquid separator, a secondary cooler, an acetic acid collection tank, and an N-cyanoethyl-N-acetoxyethyl aniline finished product tank. The first inlet of the heat exchanger is connected to the esterification reaction unit. The first outlet of the heat exchanger, which is connected to the first inlet, is connected to the inlet of the evaporator. The finished product outlet of the evaporator is connected to the N-cyanoethyl-N-acetoxyethyl aniline finished product tank. The steam outlet of the evaporator is connected to the second inlet of the heat exchanger. The second outlet of the heat exchanger, which is connected to the second inlet, is connected to the gas-liquid separator. The gas outlet of the gas-liquid separator is connected to the acetic acid collection tank through the second cooler. The liquid outlet of the gas-liquid separator is connected to the acetic acid collection tank. The acetic acid collection tank is connected to the vacuum equipment.

8. A continuous production process for N-cyanoethyl-N-acetoxyethyl aniline, characterized in that, include: The continuous production system for N-cyanoethyl-N-acetoxyethyl aniline according to any one of claims 1 to 7 utilizes a dehydration unit to dehydrate liquid N-cyanoethyl aniline to a water content of no more than 1 wt%. The liquid N-cyanoethyl aniline with a water content of no more than 1 wt% is mixed with a catalyst and ethylene oxide and then continuously fed into a hydroxylation reaction unit to produce the finished N-cyanoethyl-N-hydroxyethyl aniline product. N-cyanoethyl-N-hydroxyethyl aniline product and acetic anhydride are continuously fed into the esterification reaction unit to carry out the esterification reaction to obtain N-cyanoethyl-N-acetoxyethyl aniline solution; The N-cyanoethyl-N-acetoxyethyl aniline product was separated from the N-cyanoethyl-N-acetoxyethyl aniline solution and the acetic acid was recovered using an acetic acid recovery unit.

9. The continuous production process for N-cyanoethyl-N-acetoxyethyl aniline according to claim 8, characterized in that, Ethylene oxide was added to the hydroxylation reaction unit.

10. The continuous production process for N-cyanoethyl-N-acetoxyethyl aniline according to claim 8 or 9, characterized in that, The water content of the liquid N-cyanoethyl aniline does not exceed 0.5 wt%; The catalyst is acetic acid, and the amount used is 2% to 5% of the mass of N-cyanoethyl aniline; The molar ratio of ethylene oxide to N-cyanoethyl aniline is 0.65~1.45:1; The temperature of the hydroxylation reaction unit is controlled at 50~90℃; the material residence time in the hydroxylation reaction unit is 60~120 min, and the material circulation rate is 10~20 times the feed flow rate; The molar ratio of N-cyanoethyl-N-hydroxyethyl aniline to acetic anhydride is 1:1.05~1.15; The reaction temperature of the esterification reaction unit is controlled at 80~100℃; the material residence time of the esterification reaction unit is 60~120min. The acetic acid recovery unit recovers acetic acid to an N-cyanoethyl-N-acetoxyethyl aniline solution with a solid content of 75%~92%.

11. The continuous production process for N-cyanoethyl-N-acetoxyethyl aniline according to claim 10, characterized in that, The molar ratio of ethylene oxide to N-cyanoethyl aniline is 1.05:1; The acetic acid recovery unit recovers acetic acid to an N-cyanoethyl-N-acetoxyethyl aniline solution with a solid content of 85%~90%.

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