A method and device for continuously synthesizing N,N-dicyanoethylaniline in a microchannel

Abstract

The invention discloses a method and device for continuously synthesizing N,N-dicyanoethylaniline in a microchannel. Aniline and acrylonitrile are used as raw materials, acid / Lewis acid is used as a catalyst, and water is used as a solvent. A reaction occurs in a microchannel to continuously produce N,N-dicyanoethylaniline. The method increases the Lewis acid content to make the reaction system in a homogeneous state, thereby increasing the reaction rate; hydrochloric acid and excess acrylonitrile dissolve the solid product in situ, solving the problem of solid product blocking the microchannel; increasing the reaction pressure so that the reaction materials are in a liquid phase to improve the contact efficiency of the reaction materials; increasing the buffer tank to increase the service life of the equipment to improve the economic benefits; the process can achieve an aniline conversion rate of nearly 100% and an N,N-dicyanoethylaniline yield of more than 70% within 10 minutes, the residence time is greatly shortened, the production efficiency is greatly improved, and it is conducive to industrial production; in addition, the process is a continuous production process, which is safe and efficient and has broad application prospects.

Description

Technical Field

[0001] The invention relates to a method and a device for continuously synthesizing N,N-dicyanoethylaniline in a microchannel, belonging to the field of dye intermediate synthesis. Background Art

[0002] The dye industry is a traditional industry in the national economy. my country's dye output accounts for 70% of the world's total, and it has become the world's largest dye producer, consumer and exporter. Disperse dyes are the only dyes that can be used to dye polyester fibers, making them one of the most important varieties of all dyes.

[0003] N,N-Dicyanoethylaniline is an important disperse dye intermediate and can be used to synthesize dyes such as Disperse Yellow 163 and Disperse Orange 44. The disperse dyes produced with it as raw material have stable quality, high color intensity, good dye application performance, large market demand, and rapid market growth in the later period. It is one of the key points in the development of dye chemical industry.

[0004] The traditional synthesis method of N,N-dicyanoethylaniline (for example, patents with publication numbers: CN1166628C, CN1342645A, CN104003905B, etc.) uses aniline and acrylonitrile as raw materials, hydrochloric acid, acetic acid, zinc chloride, aluminum chloride and cupric chloride as catalysts, water as solvent, hydroquinone as inhibitor, and reflux in an intermittent reactor. Due to the strong exothermicity of the process, in order to control the temperature rise of the reaction, the catalyst content in the water phase is usually low (less than 30%), and batch addition or dropwise addition is used to slow down the reaction rate, resulting in a reaction time of up to tens of hours. In addition, the use of a large amount of water not only reduces the effective volume of the reactor and reduces production efficiency, but its separation and circulation also increase production costs. The intermittent operation mode is difficult to realize automation, increases labor intensity and labor costs, and is prone to material leakage and damage to personnel health.

[0005] In view of the above problems, the use of intrinsically safe microchannel reactors is one of the ideal ways to improve the reaction efficiency and safety of the process. Based on the efficient heat exchange capacity of microchannel reactors, the reaction rate can be accelerated and the reaction time can be shortened by increasing the catalyst content or reaction temperature; in addition, microchannel reactors can disperse droplets into micrometer scales, increasing the contact area between the organic phase and the aqueous phase, which helps to further improve the process efficiency; according to the principle of quantitative amplification, the number of parallel channels can be increased, making it easy to achieve process amplification.

[0006] The unique performance of microchannel reactors makes possible an efficient and continuous synthesis process for N,N-dicyanoethylaniline, but it has not been reported yet. Summary of the invention

[0007] The purpose of the present invention is to provide a method and a device for continuously synthesizing N,N-dicyanoethylaniline.

[0008] To achieve the above purpose, the technical solution adopted by the present invention is:

[0009] The Lewis acid in the aqueous phase is both a catalyst and a reaction solvent, so that the reaction system is in a homogeneous state, and its content is controlled at 55 to 70 wt% (preferably 58 to 65 wt%, more preferably 60 to 65 wt%);

[0010] The acid in the aqueous phase is both a catalyst and a solvent for the solid intermediate product (aniline salt). The formation of the intermediate product easily causes pipeline blockage, making it impossible to conduct experiments. Therefore, the acid content is controlled at 2.0 wt% to 4.0 wt% (preferably 2.5 wt% to 3.5 wt%, more preferably 2.5 wt% to 3.0 wt%).

[0011] Acrylonitrile in the organic phase is both a reactant and a solvent for the solid products N-cyanoethylaniline and N,N-dicyanoethylaniline, which prevents pipeline blockage. Therefore, the molar ratio of aniline to acrylonitrile is controlled at 1:2.8 to 1:5 (preferably 1:3 to 1:4.5, more preferably 1:3.5 to 1:4.5);

[0012] The reaction temperature is controlled at 115-135° C. (preferably 115-125° C., more preferably 115-120° C.) to increase the solubility of the solid product;

[0013] The reaction is pressurized by nitrogen, and the reaction pressure is controlled by a back pressure valve at the upper end of the buffer tank at 0.4-0.9 MPa (preferably 0.5-0.8 MPa, more preferably 0.5-0.7 MPa) to ensure that acrylonitrile is in a liquid phase at the reaction temperature and improve the contact efficiency between aniline and acrylonitrile;

[0014] The residence time of the organic phase-aqueous phase reaction materials in the microchannel reactor is 5 to 60 min (preferably 10 to 30 min, more preferably 10 to 20 min).

[0015] The organic phase of the invention is a mixture of aniline and acrylonitrile in a certain proportion; the aqueous phase is a mixture of water, a catalyst and an inhibitor in a certain proportion; the aqueous phase and the organic phase are mixed in a microchannel reactor to complete a cyanoethylation reaction, and then enter a buffer tank and are taken out through a sampling valve; the homogeneous product after the reaction is washed with water and then allowed to stand for stratification; the organic phase is subjected to reduced pressure distillation to obtain the product N,N-dicyanoethylaniline; the aqueous phase is supplemented with a catalyst and then used.

[0016] The catalyst is a composite catalyst composed of an acid and a Lewis acid, wherein the acid is one or more inorganic acids or organic acids such as hydrochloric acid, acetic acid, nitric acid, sulfuric acid, phosphoric acid, etc., and the Lewis acid is one or more of aluminum chloride, zinc chloride, cuprous chloride, cupric acetate, etc.; and the inhibitor is hydroquinone.

[0017] The reaction temperature of the present invention is controlled by a temperature control device, and the reaction temperature is set to 115-135°C;

[0018] The reaction pressure described in the present invention refers to the pressure in the buffer tank connected to the outlet of the microchannel reactor. The reaction pressure is controlled by the back pressure valve on the top of the buffer tank, and the reaction pressure is 0.4-0.9 MPa.

[0019] The acid content in the aqueous phase of the present invention is 2.0-4.0 wt %, the Lewis acid content in the aqueous phase solution is 55-70 wt %, and the hydroquinone content in the aqueous phase solution is 0.63 wt %;

[0020] The molar ratio of aniline to acrylonitrile in the organic phase is 1:2.8 to 1:5.

[0021] The residence time of the present invention is controlled by the volume flow of the two phases and the inner diameter and length of the microchannel reactor.

[0022] The volume flow ratio of the organic phase to the aqueous phase of the present invention is 1:2 to 1:32 (preferably 1:2 to 1:16, more preferably 1:2 to 1:4), wherein the volume flow rate of the organic phase is 35 to 560 μL / min, and the volume flow rate of the aqueous phase is 70 to 1120 μL / min.

[0023] The microchannel reactor of the present invention has an equivalent diameter of 250 to 2000 μm and a length of 2000 to 33000 mm.

[0024] Compared with the prior art, the process of continuously synthesizing N,N-dicyanoethylaniline in a microreactor adopted in the present invention has the following advantages:

[0025] (1) The present invention utilizes an intrinsically safe microreactor system for continuous operation. Under the premise that the reaction temperature is controllable, the reaction pressure is increased and the catalyst content is increased, the product selectivity is high, the yield of N,N-dicyanoethylaniline is increased, the reaction rate is accelerated, the residence time is shortened to several minutes, the production efficiency is greatly improved, and it is conducive to industrial production;

[0026] (2) The present invention uses acid and excess acrylonitrile as solvents, wherein the acid dissolves the solid intermediate product aniline salt generated by the reaction, and the acrylonitrile dissolves the solid intermediate product N-cyanoethylaniline and the solid product N,N-dicyanoethylaniline. Without introducing other solvents, the problem of microchannel blockage is solved, and the products are easier to separate;

[0027] (3) The present invention increases the Lewis acid content to make the reaction in a homogeneous state, thereby increasing the reaction rate and allowing aniline to reach a conversion rate of nearly 100% within a few minutes;

[0028] (4) The present invention uses nitrogen to pass into the buffer tank to give the reaction system back pressure, which solves the problem of equipment damage caused by the product directly entering the back pressure valve, increases the life of the equipment, reduces production costs, and increases economic benefits.

[0029] The method increases the Lewis acid content so that the reaction system is in a homogeneous state, thereby increasing the reaction rate; hydrochloric acid and excess acrylonitrile dissolve the solid product in situ, thereby solving the problem of solid product blocking the microchannel; increasing the reaction pressure so that the reaction materials are in a liquid phase, thereby improving the contact efficiency of the reaction materials; adding a buffer tank, thereby increasing the service life of the equipment, thereby improving the economic benefits; the process can achieve a nearly 100% aniline conversion rate and a more than 70% N, N-dicyanoethylaniline yield within 10 minutes, the residence time is greatly shortened, the production efficiency is greatly improved, and it is conducive to industrial production; in addition, the process is a continuous production process, which is safe and efficient and has broad application prospects.

[0030] The technical solution of the present invention is further described in detail below based on the accompanying drawings and specific implementation methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The figure shows a schematic diagram of the process of continuous synthesis of N,N-dicyanoethylaniline in a microchannel according to the present invention. In the figure: 1—organic phase injection pump; 2—aqueous phase injection pump; 3—organic phase one-way valve; 4—aqueous phase one-way valve; 5—micro mixer; 6—microchannel reactor; 7—temperature control device; 8—buffer tank; 9—sampling valve; 10—gas cylinder; 11—pressure reducing valve; 12—mass flow meter; 13—pressure gauge; 14—back pressure valve; 15—water tank;

[0032] The microchannel reaction system provided by the present invention mainly comprises: an injection pump, a one-way valve, a micro mixer, a microchannel reactor, a temperature control device, a buffer tank, a gas cylinder, and a water tank.

[0033] The organic phase is pumped into the pipeline through the organic phase injection pump 1, flows through the organic phase one-way valve 3 and then enters the micromixer 5; the aqueous phase is pumped into the pipeline through the aqueous phase injection pump 2, flows through the aqueous phase one-way valve 4 and then also enters the micromixer 5; the organic phase and the aqueous phase are mixed in the micromixer 5 and then enter the microchannel reactor 6; after the reaction is completed, the reaction product flows out of the microchannel reactor 6, enters the buffer tank 8, and is finally discharged through the sampling valve 9 installed at the lower part of the buffer tank 8.

[0034] In order to control the reaction temperature, the micro mixer 5 and the microchannel reactor 6 are placed in a temperature control device 7 (DF-101S heat-collecting constant temperature heating magnetic stirrer (Shanghai Lichen Bangxi Instrument Technology Co., Ltd.); heat transfer oil: dimethyl silicone oil (Dow Corning)). The gas outlet of the gas cylinder 10 is connected to the upper part of the buffer tank 8; the upper part of the buffer tank 8 extends through the back pressure valve 14 through a pipeline to below the water surface of the water tank 15 filled with water.

[0035] The micromixer is composed of two inlets, one outlet and a micromixing channel (inner diameter 500 μm, length 0.3 m) between them, and the microchannel reactor is composed of an FEP tube (microreaction channel) with one inlet and one outlet. DETAILED DESCRIPTION

[0036] The reaction route for synthesizing N,N-dicyanoethylaniline of the present invention is as follows:

[0037]

[0038] With aniline and acrylonitrile as starting materials, hydrochloric acid and zinc chloride as catalysts, and water as solvent, the two raw materials first generate N-cyanoethylaniline under the combined action of hydrochloric acid and zinc chloride as dual catalysts, and then N-cyanoethylaniline continues to react with acrylonitrile, and the hydrochloric acid and zinc chloride as dual catalysts continue to play a catalytic role, and finally generate N,N-dicyanoethylaniline.

[0039] Method and device for realizing continuous synthesis of N,N-dicyanoethylaniline in microchannel Figure 1 As shown,

[0040] First prepare the reaction solution:

[0041] (1) mixing aniline and acrylonitrile into one phase, preparing them in a suitable molar ratio to obtain an organic phase reaction solution, and placing it at the inlet of an organic phase injection pump;

[0042] (2) Mix water, 30% hydrochloric acid, zinc chloride and hydroquinone into one phase, prepare them in a suitable proportion to obtain an aqueous catalytic reaction solution, and place it at the inlet of an aqueous injection pump.

[0043] Before the reaction begins, first build the experimental device, then check the device for leaks, adjust the temperature control device 7 (oil bath) to the required temperature, and after the temperature stabilizes, adjust the pressure reducing valve 11, open the sampling valve 9, adjust the flow rate of the mass flow meter 12 to the maximum to empty the air in the buffer tank 8, and close the sampling valve 9. Adjust the flow rate of the mass flow meter 12 and the back pressure valve 14 until the pressure gauge 13 shows the pressure required for the experiment. At this time, bubbles will emerge at a uniform speed in the water tank filled with water. After the pressure stabilizes, close the mass flow meter 12, adjust the organic phase injection pump 1 and the aqueous phase injection pump 2 to the required flow rate, and start the organic phase injection pump and the aqueous phase injection pump at the same time. The two-phase materials are mixed through the micro mixer 5 and enter the microchannel reactor 6 for reaction. The product enters the buffer tank 8 and is taken out through the sampling valve 9.

[0044] The products were analyzed by high performance liquid chromatography (HPLC) to calculate the raw material conversion rate and product yield.

[0045] The content of the present invention is described above. The following are specific examples to demonstrate the experimental effects of the present invention. All percentages in the examples are by mass percentage.

[0046] Example 1

[0047] Before the experiment, an aqueous phase solution and an organic phase solution were first prepared, wherein the contents of each substance in the aqueous phase solution were: 60wt% zinc chloride, 2.5wt% HCl, and 0.63wt% hydroquinone; the molar ratio of aniline to acrylonitrile in the organic phase (oil phase) was 1:4, and an aqueous phase mixed solution and an organic phase mixed solution were obtained respectively.

[0048] During the experiment, the experimental temperature was set to 120°C, the reaction pressure was controlled at 0.5MPa, the microchannel reactor had an inner diameter of 500μm and a length of 6m, and the flow rates of the oil and water phases were set to 35μL / min and 70μL / min respectively, so that the residence time of the reactants in the microchannel was 11.21min.

[0049] The obtained product was quantitatively analyzed by HPLC, and it was calculated that under the conditions, the conversion rate of aniline was 99%, the yield of N,N-dicyanoethylaniline was 76%, of which by-products and N-cyanoethylaniline accounted for 23%.

[0050] Example 2

[0051] The zinc chloride content in the aqueous phase was changed to 70 wt % and the other conditions were the same as those in Example 1. The results showed that the aniline conversion rate was 92.98% and the yield of N,N-dicyanoethylaniline was 66.88%.

[0052] Example 3

[0053] The zinc chloride content in the aqueous phase was changed to 65 wt % and the other conditions were the same as those in Example 1. The results showed that the aniline conversion rate was 97.43% and the yield of N,N-dicyanoethylaniline was 72.34%.

[0054] Example 4

[0055] The zinc chloride content in the aqueous phase was changed to 58 wt % and the other conditions were the same as those in Example 1. The results showed that the aniline conversion rate was 98.31% and the yield of N,N-dicyanoethylaniline was 74.33%.

[0056] Comparative Example 1

[0057] The zinc chloride content in the aqueous phase was changed to 50 wt % and the other conditions were the same as those in Example 1. The results showed that the aniline conversion rate was 84.38% and the yield of N,N-dicyanoethylaniline was 56.37%.

[0058] Comparative Example 2

[0059] The zinc chloride content in the aqueous phase was changed to 36.6 wt % and the other conditions were the same as those in Example 1. The results showed that the aniline conversion rate was 83.10% and the yield of N,N-dicyanoethylaniline was 27.85%.

[0060] Example 5

[0061] The HCl content in the aqueous phase was changed to 3.0 wt % and the other conditions were the same as those in Example 1. The results showed that the aniline conversion rate was 94.18% and the yield of N,N-dicyanoethylaniline was 65.06%.

[0062] Comparative Example 3

[0063] The HCl content in the aqueous phase was changed to 4.7 wt % and the other conditions were the same as those in Example 1. The results showed that the aniline conversion rate was 78.46% and the yield of N,N-dicyanoethylaniline was 19.42%.

[0064] Comparative Example 4

[0065] The HCl content in the aqueous phase was changed to 6 wt % and the other conditions were the same as those in Example 1. The results showed that the aniline conversion rate was 35.03% and the yield of N,N-dicyanoethylaniline was 10.42%.

[0066] Comparative Example 5

[0067] The zinc chloride content in the aqueous phase was changed to 53.6 wt %, the HCl content was changed to 4.5 wt %, and the other conditions were the same as those in Example 1. The aniline conversion rate was 83.68%, and the yield of N,N-dicyanoethylaniline was 41.66%.

[0068] Comparative Example 6

[0069] The molar ratio of aniline to acrylonitrile was changed to 1:7, and the other conditions were the same as those in Example 1. The conversion rate of aniline was 40.26%, and the yield of N,N-dicyanoethylaniline was 6.09%.

[0070] Comparative Example 7

[0071] The HCl content in the aqueous phase was changed to 1.5wt%, the zinc chloride content was changed to 70wt%, and the other conditions were the same as in Example 1. The results showed that the aniline conversion rate was 74.03%, and the yield of N,N-dicyanoethylaniline was 57.76%.

[0072] Example 6

[0073] The reaction temperature was changed to 115° C., and the other conditions were the same as those in Example 1. The results showed that the conversion rate of aniline was 97.21%, and the yield of N,N-dicyanoethylaniline was 73.24%.

[0074] Example 7

[0075] The reaction temperature was changed to 125° C., and the other conditions were the same as those in Example 1. The results showed that the conversion rate of aniline was 94.33%, and the yield of N,N-dicyanoethylaniline was 70.09%.

[0076] Example 8

[0077] The reaction temperature was changed to 135° C., and the other conditions were the same as those in Example 1. The results showed that the conversion rate of aniline was 90.30%, and the yield of N,N-dicyanoethylaniline was 62.18%.

[0078] Example 9

[0079] The zinc chloride content in the aqueous phase was changed to 55 wt % and the other conditions were the same as those in Example 4. The results showed that the aniline conversion rate was 90.73% and the yield of N,N-dicyanoethylaniline was 61.77%.

[0080] Example 10

[0081] The pressure was changed to 0.4 MPa, and the other conditions were the same as those in Example 1. The results showed that the conversion rate of aniline was 97.83%, and the yield of N,N-dicyanoethylaniline was 73.28%.

[0082] Embodiment 11

[0083] The pressure was changed to 0.7 MPa, and the other conditions were the same as those in Example 1. The results showed that the conversion rate of aniline was 98.52%, and the yield of N,N-dicyanoethylaniline was 75.23%.

[0084] Example 12

[0085] The pressure was changed to 0.9 MPa, and the other conditions were the same as those in Example 1. The results showed that the conversion rate of aniline was 97.62%, and the yield of N,N-dicyanoethylaniline was 74.15%.

[0086] Embodiment 13

[0087] The tube length was changed to 3 m, the residence time was 5.61 min, and the other conditions were the same as those in Example 1. The results showed that the aniline conversion rate was 91.96%, and the yield of N,N-dicyanoethylaniline was 63.59%.

[0088] Embodiment 14

[0089] The tube length was changed to 32 m, the residence time was 59.81 min, and the other conditions were the same as those in Example 1. The results showed that the aniline conversion rate was 90.63%, and the yield of N,N-dicyanoethylaniline was 67.23%.

[0090] Embodiment 15

[0091] The tube length was changed to 16 m, the residence time was 29.90 min, and the other conditions were the same as those in Example 1. The results showed that the aniline conversion rate was 94.67%, and the yield of N,N-dicyanoethylaniline was 68.72%.

[0092] Example 16

[0093] The tube length was changed to 8 m, the residence time was 14.95 min, and the other conditions were the same as those in Example 1. The results showed that the aniline conversion rate was 96.33%, and the yield of N,N-dicyanoethylaniline was 70.68%.

[0094] Embodiment 17

[0095] The tube length was changed to 5.5 m, the residence time was 10.28 min, and the other conditions were the same as those in Example 1. The results showed that the aniline conversion rate was 95.27% and the yield of N,N-dicyanoethylaniline was 69.71%.

[0096] Comparative Example 8

[0097] The zinc chloride content in the aqueous phase was changed to 36.6 wt % and the other conditions were the same as those in Example 4. The results showed that the aniline conversion rate was 75.63% and the yield of N,N-dicyanoethylaniline was 20.21%.

[0098] Comparative Example 9

[0099] The zinc chloride content in the aqueous phase was changed to 30 wt % and the other conditions were the same as those in Example 4. The results showed that the aniline conversion rate was 63.26% and the yield of N,N-dicyanoethylaniline was 10.54%.

[0100] Comparative Example 10

[0101] The pressure was changed to 0.2 MPa, and the other conditions were the same as those in Example 4. The results showed that the conversion rate of aniline was 78.78%, and the yield of N,N-dicyanoethylaniline was 36.69%.

[0102] Comparative Example 11

[0103] The molar ratio of acrylonitrile to aniline was changed to 2.5:1, and the other conditions were the same as those in Example 4. The results showed that the solid intermediate product (N-cyanoethylaniline) generated by the reaction was not enough to be dissolved by acrylonitrile, resulting in microchannel blockage and the reaction could not proceed normally.

[0104] Comparative Example 12

[0105] The HCl content in the aqueous phase was changed to 1.0 wt %, and the other conditions were the same as those in Example 4. The results showed that the solid intermediate product (aniline salt) generated by the reaction was not sufficiently dissolved by the acid, resulting in clogging of the microchannel and failure of the reaction to proceed normally.

[0106] Comparative Example 13

[0107] The temperature was changed to 100° C., and the other conditions were the same as in Example 4. The results showed that the solubility of the solid intermediates (aniline salt and N-cyanoethylaniline) and the solid products (N,N-cyanoethylaniline) generated by the reaction in acid and acrylonitrile decreased, causing the microchannel to be blocked and the reaction could not proceed normally.

[0108] Comparative Example 14

[0109] The molar ratio of aniline to acrylonitrile was changed to 1:7, and the other conditions were the same as those in Example 4. The results showed that the conversion rate of aniline was 39.35%, and the yield of N,N-dicyanoethylaniline was 5.04%.

[0110] Comparative Example 15

[0111] The tube length was changed to 1 m, the residence time was 3.74 min, and the other conditions were the same as those in Example 1. The results showed that the aniline conversion rate was 84.38%, and the yield of N,N-dicyanoethylaniline was 56.43%.

[0112] Comparative Example 16

[0113] The molar ratio of acrylonitrile to aniline was changed to 2.5:1, the pressure was 0.3 MPa, the temperature was 110°C, the tube length was 18 m, the residence time was 33.64 min, the zinc chloride content in the aqueous phase was 36.6 wt%, and the HCl content was 4.7 wt%. The results showed that the aniline conversion rate was 68.67% and the yield of N,N-dicyanoethylaniline was 22.42%.

[0114] Comparative Example 17

[0115] The temperature was changed to 160° C. and the pressure was changed to 1 MPa. The other conditions were the same as those in Example 4. The results showed that the conversion rate of aniline was 70.52% and the yield of N,N-dicyanoethylaniline was 18.56%.

[0116] Comparative Example 18

[0117] The Lewis acid was changed to AlCl3, the content of which in the aqueous phase was 50 wt %, and the other conditions were the same as those in Example 1. The results showed that the conversion rate of aniline was 85.28%, and the yield of N,N-dicyanoethylaniline was 53.54%.

[0118] Embodiment 18

[0119] The inner diameter of the channel was changed to 2000 μm, the channel length was changed to 2000 mm, the volume flow rate of the organic phase was changed to 140 μL / min, the volume flow rate of the aqueous phase was changed to 280 μL / min, the residence time was 14.95 min, and the other conditions were the same as in Example 1. The results showed that the conversion rate of aniline was 98.35%, and the yield of N,N-dicyanoethylaniline was 74.26%.

[0120] Embodiment 19

[0121] The molar ratio of aniline to acrylonitrile was changed to 1:3, and the other conditions were the same as those in Example 4. The results showed that the conversion rate of aniline was 93.20%, and the yield of N,N-dicyanoethylaniline was 68.53%.

[0122] Embodiment 20

[0123] The molar ratio of aniline to acrylonitrile was changed to 1:3.5, and the other conditions were the same as those in Example 4. The results showed that the conversion rate of aniline was 95.27%, and the yield of N,N-dicyanoethylaniline was 69.66%.

[0124] Embodiment 21

[0125] The molar ratio of aniline to acrylonitrile was changed to 1:4.5, and the other conditions were the same as those in Example 4. The results showed that the conversion rate of aniline was 96.37%, and the yield of N,N-dicyanoethylaniline was 72.64%.

[0126] Embodiment 22

[0127] The molar ratio of aniline to acrylonitrile was changed to 1:5, and the other conditions were the same as those in Example 4. The results showed that the conversion rate of aniline was 94.28%, and the yield of N,N-dicyanoethylaniline was 62.17%.

[0128] Comparative Example 19

[0129] The micromixer was not placed in the temperature control device, and the other conditions were the same as in Example 4. The results showed that the solid intermediate product (aniline salt) generated by the reaction was not sufficiently dissolved by the acid at room temperature, causing the micromixer to be blocked and the reaction could not proceed normally.

[0130] Embodiment 23

[0131] The hydroquinone content in the aqueous phase was changed to 0.4 wt % and the other conditions were the same as those in Example 4. The results showed that the aniline conversion rate was 89.32% and the yield of N,N-dicyanoethylaniline was 64.83%.

[0132] Embodiment 24

[0133] The hydroquinone content in the aqueous phase was changed to 0.5 wt % and the other conditions were the same as those in Example 4. The results showed that the aniline conversion rate was 94.63% and the yield of N,N-dicyanoethylaniline was 70.33%.

[0134] Embodiment 25

[0135] The hydroquinone content in the aqueous phase was changed to 0.6 wt % and the other conditions were the same as those in Example 4. The results showed that the aniline conversion rate was 98.55% and the yield of N,N-dicyanoethylaniline was 75.93%.

[0136] Embodiment 26

[0137] The hydroquinone content in the aqueous phase was changed to 0.8 wt % and the other conditions were the same as those in Example 4. The results showed that the aniline conversion rate was 98.68% and the yield of N,N-dicyanoethylaniline was 75.96%.

[0138] Comparative Example 20

[0139] The hydroquinone content in the aqueous phase was changed to 0%, and the other conditions were the same as those in Example 4. The results showed that the aniline conversion rate was 79.64%, and the yield of N,N-dicyanoethylaniline was 53.24%.

[0140] Comparative Example 21

[0141] The hydroquinone content in the aqueous phase was changed to 0.2 wt % and the other conditions were the same as those in Example 4. The results showed that the aniline conversion rate was 89.47% and the yield of N,N-dicyanoethylaniline was 57.35%.

[0142] Embodiment 27

[0143] The volume flow rate of the aqueous phase was changed to 1120 μL / min, and the other conditions were the same as those in Example 1. The results showed that the conversion rate of aniline was 90.15%, and the yield of N,N-dicyanoethylaniline was 60.27%.

[0144] Embodiment 28

[0145] The volume flow rate of the aqueous phase was changed to 560 μL / min, and the other conditions were the same as those in Example 1. The results showed that the conversion rate of aniline was 93.64%, and the yield of N,N-dicyanoethylaniline was 64.67%.

[0146] Embodiment 29

[0147] The volume flow rate of the aqueous phase was changed to 140 μL / min, and the other conditions were the same as those in Example 1. The results showed that the conversion rate of aniline was 94.37%, and the yield of N,N-dicyanoethylaniline was 70.60%.

[0148] Comparative Example 22

[0149] The volume flow rate of the aqueous phase was changed to 35 μL / min, and the other conditions were the same as in Example 29. The results showed that the solid intermediate product (aniline salt) generated by the reaction was not sufficiently dissolved, causing the micromixer to be blocked and the reaction could not proceed normally.

[0150] Embodiment 30

[0151] The zinc chloride content in the aqueous phase was changed to 65wt%, the HCl content was changed to 3.5wt%, the hydroquinone content was changed to 3.5wt%, and the other conditions were the same as those in Example 1. The results showed that the aniline conversion rate was 93.27% and the yield of N,N-dicyanoethylaniline was 65.48%.

Claims

1. A method for continuously synthesizing N,N-dicyanoethylaniline in a microchannel, characterized in that: Mixing aniline and acrylonitrile to obtain an organic phase; mixing water, a catalyst and a polymerization inhibitor to obtain an aqueous phase; The aqueous phase and the organic phase are mixed in a microchannel reactor for cyanoethylation reaction, or the aqueous phase and the organic phase are mixed in a micromixer and then enter the microchannel reactor for cyanoethylation reaction. After the reaction, the material enters a sealed tank body, the upper part of the tank body is connected to an air source providing air pressure in the tank body through a pipeline, and a material outlet is provided at the lower part of the tank body; The catalyst is a composite catalyst composed of an acid and a Lewis acid, the acid is one or more of hydrochloric acid, acetic acid, nitric acid, sulfuric acid, and phosphoric acid, and the Lewis acid is one or more of aluminum chloride, zinc chloride, cuprous chloride, and cupric acetate; The Lewis acid content of the catalyst in the water phase is 55-70 wt%; The catalyst acid content in the aqueous phase is 2.0~4.0 wt%; The molar ratio of aniline to acrylonitrile in the organic phase is controlled at 1:2.8 to 1:5; The reaction temperature at the microchannel in the microchannel reactor is controlled at 115~135℃; The pressure inside the tank is 0.4~0.9 MPa; The residence time of the organic phase-aqueous phase reaction materials in the microchannel reactor is 5 to 60 min, and the volume flow ratio of the organic phase to the aqueous phase is 1:2 to 1:

32.

2. The method according to claim 1, characterized in that: The Lewis acid content of the catalyst in the aqueous phase is 58-65 wt%; The catalyst acid content in the aqueous phase is 2.5-3.5 wt%; The molar ratio of aniline to acrylonitrile in the organic phase is controlled at 1:3 to 1:4.5; The reaction temperature at the microchannel in the microchannel reactor is controlled at 115~125℃; The pressure inside the tank is 0.5~0.8 MPa; The residence time of the organic phase-aqueous phase reaction materials in the microchannel reactor is 10~30 min.

3. The method according to claim 1, characterized in that: The Lewis acid content of the catalyst in the water phase is 60-65 wt%; The catalyst acid content in the aqueous phase is 2.5-3.0 wt%; The molar ratio of aniline to acrylonitrile in the organic phase is controlled at 1:3.5 to 1:4.5; The reaction temperature at the microchannel in the microchannel reactor is controlled at 115-120 °C; The pressure inside the tank is 0.5~0.7 MPa; The residence time of the organic phase-aqueous phase reaction materials in the microchannel reactor is 10~20 min.

4. The method according to claim 1, characterized in that: The polymerization inhibitor is hydroquinone.

5. The method according to claim 4, characterized in that: The content of the inhibitor in the aqueous phase solution is 0.4-0.8wt%.

6. The method according to claim 4, characterized in that: The content of the inhibitor in the aqueous phase solution is 0.5-0.8 wt %.

7. The method according to claim 4, characterized in that: The content of the inhibitor in the aqueous phase solution is 0.6-0.65wt%.

8. The method according to claim 1, characterized in that: The volume flow ratio of the organic phase to the aqueous phase is 1:2 to 1:

16.

9. The method according to claim 1, characterized in that: The volume flow ratio of the organic phase to the aqueous phase is 1:2 to 1:

4.

10. The method according to claim 1, characterized in that: The residence time is controlled by the volume flow of the two phases and the inner diameter and length of the microchannel reactor; The volume flow rate of the organic phase is 35~560 µL / min, and the volume flow rate of the aqueous phase is 70~1120 µL / min; The microchannel reactor has an equivalent diameter of 250-2000 μm and a length of 2000-33000 mm.

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