Production and purification method and device of N-cyanoethyl-N benzyl aniline

Abstract

The invention discloses a method and a device for producing and purifying N-cyanoethyl-N benzyl aniline. The production and purification device comprises a benzylation reaction kettle, a crystallizer, a crystallization kettle and a solid-liquid separation device. The production and purification method comprises the following steps: S1, reacting N-cyanoethyl aniline with benzyl chloride in a benzylation reaction kettle to obtain an N-cyanoethyl-N benzylaniline crude product; s2, acid is added into the benzylation reaction kettle to adjust the benzylation reaction kettle to be acidic, then standing and layering are conducted, and upper-layer oil liquid is put into a crystallizer; s3, cooling and crystallizing in a crystallizer; s4, heat preservation sweating is conducted in the crystallizer, and sweat is led out; and S5, melting the crystals in the crystallizer, discharging into a crystallization kettle, adding water, cooling, crystallizing, and carrying out solid-liquid separation to obtain purified N-cyanoethyl-N-benzylaniline solid. The HPLC (High Performance Liquid Chromatography) purity of the purified N-cyanoethyl-N benzylaniline solid is greater than or equal to 98%, and the HPLC detection result of the N-cyanoethyl aniline is less than or equal to 0.5%.

Description

Technical Field

[0001] The invention relates to the field of dye intermediates, and in particular to a production and purification method and device for N-cyanoethyl-N-benzylaniline. Background Art

[0002] N-Cyanoethyl-N-benzylaniline is an important dye intermediate, commonly used in the synthesis of SE type (medium temperature type) disperse dyes.

[0003] At present, the process of producing N-cyanoethyl-N-benzylaniline by domestic chemical enterprises is mainly as follows: cyanoethylaniline, benzyl chloride, bottom water and soda ash are put into the benzylation reaction kettle, the temperature is raised to 105-110℃ for reaction, it takes 7 hours to reach the temperature, and the temperature is kept for more than 10 hours after the temperature is raised to obtain the semi-finished product of N-cyanoethyl-N-benzylaniline with purity (HPLC) ≥93% and N-cyanoethylaniline ≤3%. After the reaction is completed, a certain amount of water is added for dilution, the temperature is lowered for crystallization, and the finished product of N-cyanoethyl-N-benzylaniline with purity (HPLC) ≥94%, N-cyanoethylaniline ≤3%, and N,N-dicyanoethylaniline ≤2% is obtained after filtering and washing. This method has the following shortcomings:

[0004] (1) The reaction time is long and the energy consumption is high. In the benzylation reaction process, the raw materials benzyl chloride and N-cyanoethylaniline are reacted at a molar ratio of 1 to 1.15:1. When the temperature is raised to 105-110°C for 7 hours, the conversion rate of the raw material N-cyanoethylaniline can reach about 88%. If the temperature is kept at this temperature for 1 hour to 2 hours, the conversion rate can reach about 94%. However, as the raw material concentration decreases, the reaction is continued until the qualified conversion rate of N-cyanoethylaniline reaches 97%. The reaction time needs to be more than 10 hours. If the conversion rate is to reach more than 98%, the ratio of benzyl chloride can only be increased.

[0005] (2) Benzyl chloride, a raw material, is the main substance that affects the environmental protection index of downstream dye products (oeko-tex standard 100 ecological environmental protection standard). Benzyl chloride is not only a substance harmful to the human body, but also when its content in the product is high, it will lead to high levels of other chlorinated aromatic hydrocarbons harmful to the human body, such as dichlorotoluene. The above-mentioned harmful substances are difficult to separate from the product, and the separation and treatment requires high costs. Therefore, enterprises often make a slight excess of benzyl chloride in the raw material ratio to minimize the content of benzyl chloride in the product.

[0006] (3) The raw material N-cyanoethylaniline is a major impurity that affects the application indicators of downstream dye products, such as the dispersibility and fiber dispersion of the dye. In the process of synthesizing the dye, this substance can undergo a coupling reaction with the diazotizing agent to generate a useless black solid substance that exists in the dye mother liquor and the dye. This not only causes a waste of the diazotizing agent and affects the quality of the product application indicators, but also generates excess solid waste in the dye production process. In the current main production process, it is difficult to further reduce the content of the raw material N-cyanoethylaniline while taking into account environmental protection indicators during the benzylation reaction.

[0007] (4) In the existing process, water is directly added to dilute the crystals during post-treatment, which will produce a large amount of high-salt wastewater that is difficult to treat.

[0008] With the development of society, the country and the people pay more and more attention to environmental protection and health. Improving product quality, producing green and healthy products to improve product competitiveness, and saving energy, reducing emissions and reducing energy consumption costs have gradually become a consensus among chemical companies; N-cyanoethyl-N-benzylaniline, as an important dye intermediate product, has a large production capacity, but the existing process methods have many shortcomings. Therefore, it is particularly necessary to develop a production and purification method for N-cyanoethyl-N-benzylaniline to achieve the purpose of improving quality, energy saving and environmental protection. Summary of the invention

[0009] In view of the above technical problems and the shortcomings in the art, the present invention provides a production and purification method and device for N-cyanoethyl-N-benzylaniline. The present invention not only reduces the generation of wastewater and solid waste, reduces production energy consumption, but also improves the quality of the intermediate itself and downstream dye products. The HPLC purity of the N-cyanoethyl-N-benzylaniline produced and purified by the present invention is ≥98%, and the HPLC test result of the raw material N-cyanoethylaniline is ≤0.5%. The downstream dye product synthesized by the N-cyanoethyl-N-benzylaniline produced and purified by the present invention has excellent application quality indicators, and the environmental protection indicators meet the oeko-texstandard 100 ecological environmental protection standards.

[0010] [1] A production and purification device for N-cyanoethyl-N-benzylaniline, comprising a benzylation reaction kettle, a crystallizer, a crystallization kettle and a solid-liquid separation device;

[0011] The benzylation reaction kettle is at least used for the reaction of N-cyanoethylaniline and benzyl chloride to obtain a crude N-cyanoethyl-N-benzylaniline product, and after the reaction is completed, acid is added to adjust the acidity and then allowed to stand for stratification to form a lower layer of mother liquor and an upper layer of oil liquid;

[0012] The crystallizer is at least used to receive the upper oil liquid from the benzylation reaction kettle, and after receiving the upper oil liquid, sequentially performs cooling crystallization, heat preservation and sweating, and conducts out sweat and molten crystals;

[0013] The crystallization kettle is at least used to receive the molten crystals from the crystallizer and add water to dilute and cool the crystals;

[0014] The solid-liquid separation device is at least used for solid-liquid separation of the mixture obtained by cooling and crystallizing the crystallization kettle to obtain the purified N-cyanoethyl-N-benzylaniline solid.

[0015] In some embodiments, the production and purification device described above, the crystallizer may be provided with a jacket, and a first heat exchange medium is provided in the jacket, and the first heat exchange medium is used at least for cooling crystallization and heat preservation and sweating. The present invention does not specifically limit the first heat exchange medium, for example, the first heat exchange medium may be water, steam, etc.

[0016] In some embodiments, the production and purification device may include a heating tube in the crystallizer, and a second heat exchange medium may be provided in the heating tube, and the second heat exchange medium may be used at least for heat preservation and sweating. The second heat exchange medium may not be particularly limited in the present invention, for example, the second heat exchange medium may be water, steam, etc.

[0017] Furthermore, the heating tubes can be vertically distributed in the crystallizer, and the vertical distribution is beneficial to reducing the resistance to the upward flow of the fluid.

[0018] In some embodiments, the production and purification device may also include a guide tube and a stratification kettle; the bottom of the crystallizer is connected to the stratification kettle; the stratification kettle is at least used to introduce circulating water into the crystallizer through the bottom of the crystallizer to drain sweat; an overflow port is provided at the top of the crystallizer, and the overflow port is connected to the guide tube; the guide tube is at least used to receive the circulating water and sweat flowing out of the crystallizer through the overflow port, and guide the circulating water and sweat to the middle and lower part of the stratification kettle.

[0019] The lower layer in the layered kettle is sweat, and the upper layer is circulating water. The lower layer sweat in the layered kettle can be recycled for benzylation reaction. In some embodiments, in the production and purification device, a water pipe can be set in the layered kettle corresponding to the circulating water layer, and the water pipe is connected to the bottom of the crystallizer. The layered kettle passes circulating water into the crystallizer through the water pipe to drain the sweat.

[0020] [2] Use of the production and purification device described in [1] for producing and purifying N-cyanoethyl-N-benzylaniline.

[0021] [3] A method for producing and purifying N-cyanoethyl-N-benzylaniline, comprising the steps of:

[0022] S1, in a benzylation reaction kettle, N-cyanoethylaniline and benzyl chloride react to obtain a crude N-cyanoethyl-N-benzylaniline product;

[0023] S2, adding acid to the benzylation reaction kettle to adjust to acidity and then letting it stand to separate into layers, and putting the upper layer of oil into a crystallizer;

[0024] S3, cooling and crystallization in the crystallizer;

[0025] S4, keeping warm in the crystallizer to sweat and drain out the sweat;

[0026] S5, melting the crystals in the crystallizer, discharging them into a crystallization kettle, adding water, cooling and crystallizing, and performing solid-liquid separation to obtain the purified N-cyanoethyl-N-benzylaniline solid.

[0027] In some embodiments, in step S1, the molar ratio of N-cyanoethylaniline and benzyl chloride may be 1:0.93-1. Further, the molar ratio of N-cyanoethylaniline and benzyl chloride may be 1:x, 0.93≤x<1. For example, x may be 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, etc.

[0028] In some embodiments, in step S1, the insulation temperature for the reaction of N-cyanoethylaniline and benzyl chloride may be 105-110°C.

[0029] In some embodiments, in step S1, the reaction time of N-cyanoethylaniline and benzyl chloride at the insulation temperature can be 2 to 10 hours. Further, using the production and purification method of the present invention, in step S1, the reaction time of N-cyanoethylaniline and benzyl chloride at the insulation temperature does not need to be as long as 10 hours in the prior art, for example, it can be as long as 2 hours.

[0030] In some embodiments, in step S1, the HPLC test results show that in the crude N-cyanoethyl-N-benzylaniline: N-cyanoethylaniline ≤6%, N,N-dicyanoethylaniline ≤2%, N-cyanoethyl-N-benzylaniline ≥90%, and other impurities ≤2%.

[0031] In some embodiments, in step S2, the acid added to the benzylation reaction kettle may include one or more of sulfuric acid, hydrochloric acid, and acetic acid, preferably hydrochloric acid.

[0032] In some embodiments, in step S2, the acidity refers to a hydrogen ion concentration of 10 -5 ~1mol / L, preferably refers to a hydrogen ion concentration of 10 -4 ~10 -3 mol / L.

[0033] The melting point of the pure N-cyanoethyl-N-benzylaniline product is about 102°C, the melting point of N-cyanoethylaniline is about 52°C, and the melting point of N,N-dicyanoethylaniline is about 83°C. Accordingly, in step S3, the crystallization temperature should be lower than 52°C, preferably not more than 50°C, and further can be 45-50°C. In step S4, the temperature of heat preservation and sweating should be higher than 52°C and lower than 102°C, preferably 60-75°C, such as 70°C, 75°C, etc.

[0034] In some embodiments, in step S4, circulating water may be used to guide the sweat; the temperature of the circulating water is consistent with the temperature of the sweating insulation. Further, the hourly flow rate of the circulating water may be 0.5 to 3 times the mass of the crystals in the crystallizer, for example, 2 times.

[0035] In some embodiments, in step S5, the crystal water obtained by solid-liquid separation can be used as the bottom water jacket in step S1.

[0036] In some embodiments, in step S5, the purified N-cyanoethyl-N-benzylaniline solid is a powder and / or needle-shaped product.

[0037] In step S5, the HPLC purity of the purified N-cyanoethyl-N-benzylaniline solid is ≥98%, and the HPLC detection result of N-cyanoethylaniline is ≤0.5%.

[0038] In some embodiments, the production purification method may use the production purification device described in [1].

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] 1. The reaction time of the benzylation process in the prior art at a heat preservation temperature is as long as more than 10 hours, while the reaction time of the benzylation process in the present invention at a heat preservation temperature is greatly shortened to about 2 hours, and the production energy consumption is low.

[0041] 2. Due to the alkalinity, stratification is impossible. The post-treatment of the prior art products is to directly add water for dilution and crystallization, which produces a large amount of difficult-to-treat high-salt wastewater. The acidic stratification process in the present invention has a good stratification effect and reduces the output of high-salt wastewater by more than 2 times.

[0042] 3. The prior art products have either high N-cyanoethylaniline or high benzyl chloride content, and it is impossible to reduce the content of both in the product at the same time. The present invention utilizes a crystallization sweating process to reduce the molar ratio of benzyl chloride to N-cyanoethylaniline to 0.93-1:1, so that N-cyanoethylaniline is excessive, and the excess raw material N-cyanoethylaniline is separated and recovered by sweating, and trace residual benzyl chloride in the product can also be removed by sweat extraction. The product has high purity and low content of N-cyanoethylaniline and benzyl chloride. The downstream dye product synthesized by using N-cyanoethyl-N-benzylaniline produced by the present invention has excellent application index quality, and the environmental protection index meets the oeko-texstandard100 ecological environmental protection standard, and no solid waste is generated.

[0043] 4. The crystallizer of the present invention has a simple structure, and reasonably combines the characteristics that the density of sweat is lower than the density of the product, but slightly higher than the density of water, and is insoluble in water. Hot water is used to carry the sweat from bottom to top in the crystallizer, and a small amount of molten product always sinks to the bottom of the crystallizer due to its high density. At the same time, the sweat can extract the liquid benzyl chloride, sweating quickly, and the separation efficiency is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 The present invention is a schematic diagram of the structure of a production and purification device for N-cyanoethyl-N-benzylaniline. DETAILED DESCRIPTION

[0045] The present invention will be further described below in conjunction with the accompanying drawings and specific examples. It should be understood that these examples are only intended to illustrate the present invention and are not intended to limit the scope of the present invention. The operating methods in the following examples without specifying specific conditions are usually carried out under conventional conditions or under conditions recommended by the manufacturer.

[0046] See also Figure 1 A production and purification device for N-cyanoethyl-N-benzylaniline includes a benzylation reaction kettle 1, a crystallizer 2, a crystallization kettle (not shown), a solid-liquid separation device (not shown), a draft tube 4 and a layering kettle 3.

[0047] The benzylation reaction kettle 1 is provided with a stirring mechanism, which is at least used for the reaction of N-cyanoethylaniline and benzyl chloride to obtain a crude N-cyanoethyl-N-benzylaniline product, and for adding acid to adjust the reaction to acidity after the reaction is completed and then standing to separate into a lower layer of mother liquor and an upper layer of oil liquid.

[0048] The crystallizer 2 is a conical structure, which is at least used to receive the upper oil from the benzylation reactor 1, and after receiving the upper oil, it is cooled and crystallized, heat-insulated and sweated, and sweat and molten crystals are discharged in sequence. The crystallizer 2 is provided with a jacket 9, and the jacket 9 contains a first heat exchange medium (water, steam, etc.), and the first heat exchange medium is at least used for cooling and crystallization and heat-insulating and sweating. The crystallizer 2 is provided with a heating tube 7, and the heating tube 7 contains a second heat exchange medium (water, steam, etc.), and the second heat exchange medium is at least used for heat-insulating and sweating. The heating tube 7 is vertically distributed in the crystallizer 2, and the vertical distribution is conducive to reducing the resistance of the fluid flowing upward. The top of the crystallizer 2 is provided with a feed port connected to the discharge pipe of the benzylation reactor 1, the bottom is provided with a discharge port, and the upper part is provided with an overflow port 8, and the overflow port 8 is connected to the guide tube 4. The guide tube 4 is at least used to receive the circulating hot water and sweat flowing out of the crystallizer 2 through the overflow port 8, and guide the circulating hot water and sweat to the middle and lower part of the stratification reactor 3. When in use, the bottom of the overflow port 8 can be 0-5 cm lower than the material layer in the crystallizer 2, and the top can be more than 5 cm higher than the material layer.

[0049] The crystallization kettle is at least used to receive the molten crystals from the crystallizer 2 and add water to dilute and cool the crystals.

[0050] The solid-liquid separation device is a filtering device, which is at least used for solid-liquid separation of the mixture obtained by cooling and crystallizing the crystallization kettle to obtain the purified N-cyanoethyl-N-benzylaniline solid.

[0051] The layered kettle 3 is a conical structure with a jacket, and the guide tube 4 is arranged in the layered kettle 3. The layered kettle 3 is provided with a feed port at the top, a discharge port at the bottom, and a water guide pipe at the top. The layered kettle 3 is at least used to pass circulating hot water into the crystallizer 2 through the bottom of the crystallizer 2 to guide out sweat. The lower layer in the layered kettle 3 is sweat, and the upper layer is circulating hot water. The water guide pipe 10 is arranged in the layered kettle 3 at a position corresponding to the circulating hot water layer, and the water guide pipe 10 is connected to the siphon tank 5, and the siphon tank 5 is connected to the bottom of the crystallizer 2 through the hot water pump 6. The layered kettle 3 passes circulating water into the crystallizer 2 through the water guide pipe 10, the siphon tank 5 and the hot water pump 6 to guide out sweat.

[0052] The exemplary sweat purification process is described as follows: the hot water pump 6 draws hot water from the upper part of the stratification kettle 3 and pumps it into the crystallizer 2 from the bottom of the crystallizer 2. The hot water carries the sweat from the overflow port 8 of the crystallizer 2 through the upper feed port of the stratification kettle 3 into the stratification kettle 3, flows downward along the guide tube 4 in the stratification kettle 3 and stratifies. The sweat flows into the conical bottom of the stratification kettle 3, and the hot water floats up and circulates back to the hot water pump 6 through the water guide pipe 10.

[0053] Embodiment 1:

[0054] A method for producing and purifying N-cyanoethyl-N-benzylaniline, using the above-mentioned Figure 1 The production and purification device of N-cyanoethyl-N-benzylaniline shown comprises the steps of:

[0055] 1) Add 160 kg of bottom water into the benzylation reactor, start stirring, add 120 kg of N-cyanoethylaniline, 96.7 kg of benzyl chloride, and 41 kg of soda ash. After adding, heat to 80°C and then reduce the heating rate. According to the temperature of the reaction, heat to 105-110°C evenly within 7 hours. After heating, keep the temperature for 2 hours and take samples. The purity of the samples (HPLC): N-cyanoethyl-N-benzylaniline 90.5%, N-ethylaniline 5.8%, N,N-dicyanoethylaniline 1.8%.

[0056] 2) Add 550g of 31wt% hydrochloric acid to the benzylation reactor and adjust the pH to 3-4. After adjustment, turn off the stirring, let it stand for 0.5 hour to separate the layers, separate 181kg of the lower high-salt mother liquor to the mother liquor tank, and put the remaining oil layer into the crystallizer. After the discharge, the upper end surface of the material layer is at the same level as the bottom of the crystallizer overflow port, and the top of the overflow port is about 5cm higher than the overflow port.

[0057] 3) 45°C hot water is passed through the jacket of the crystallizer to crystallize the product (the melting point of the pure product is about 102°C, the melting point of N-cyanoethylaniline is about 52°C, and the melting point of N,N-dicyanoethylaniline is about 83°C).

[0058] 4) 70°C hot water is passed through the jacket and heating tube of the crystallizer to start sweating. When sweat is visibly produced, the hot water pump is turned on to pass the 70°C hot water preheated in the stratification kettle into the crystallizer from the bottom of the crystallizer, and the hot water flow rate is controlled at 420kg / h.

[0059] 5) Oily sweat can be seen on the surface of the solid material layer in the crystallizer. The upper layer of the sweat is hot water. The hot water and sweat flow into the stratification kettle from the overflow port of the crystallizer through the upper feed port of the stratification kettle. The fluid flows along the guide tube to the middle and lower end of the stratification kettle. After passing through the lower end of the guide tube, the sweat sinks to the cone bottom of the stratification kettle and gathers. The hot water floats up and covers the water guide pipe of the stratification kettle.

[0060] 6) After sweating for 0.5 h, when no sweat is produced on the surface of the crystallizer material layer, sweating is stopped, and the crystals in the crystallizer and the sweat at the bottom of the layered kettle are taken to test the purity. The crystal purity (HPLC): N-cyanoethyl-N-benzylaniline 97.8%, N-ethylaniline 0.6%, N,N-dicyanoethylaniline 0.8%; the sweat purity (HPLC): N-cyanoethyl-N-benzylaniline 15.8%, N-ethylaniline 67.4%, N,N-dicyanoethylaniline 12.7%; the dry weight of sweat is 15.35 kg.

[0061] 7) Steam is introduced into the jacket and heating tube of the crystallizer, and the temperature is raised to 105° C. After the crystals are melted, they are placed in a crystallization kettle, 300 kg of water is added, the temperature is lowered for crystallization, and the product is filtered to obtain a needle-shaped N-cyanoethyl-N-benzylaniline solid product with a purity (HPLC): N-cyanoethyl-N-benzylaniline 98.4%, N-ethylaniline 0.3%, and N,N-dicyanoethylaniline 0.4%; the crystallization water jacket is used for reaction bottom water.

[0062] The N-cyanoethyl-N-benzylaniline product obtained in this example was used to synthesize a dye. The dye detection environmental protection indicators showed that the benzyl chloride content was 1.22 ppm and the dichlorotoluene content was 0.69 ppm, which met the oeko-texstandard 100 ecological and environmental protection standard; the dye detection application indicators were qualified.

[0063] Embodiment 2:

[0064] A method for producing and purifying N-cyanoethyl-N-benzylaniline, using the above-mentioned Figure 1 The production and purification device of N-cyanoethyl-N-benzylaniline shown comprises the steps of:

[0065] 1) Add 160 kg of bottom water into the benzylation reactor, start stirring, add 120 kg of N-cyanoethylaniline, 96.7 kg of benzyl chloride, and 41 kg of soda ash. After adding, heat to 80°C and then reduce the heating rate. According to the temperature of the reaction, heat to 105-110°C evenly within 7 hours. After heating, keep the temperature for 10 hours and take samples. The purity of the samples (HPLC): N-cyanoethyl-N-benzylaniline 92.5%, N-ethylaniline 4.2%, N,N-dicyanoethylaniline 1.5%.

[0066] 2) Add 500g of 31wt% hydrochloric acid to the benzylation reactor and adjust the pH to 3-4. After adjustment, turn off the stirring, let it stand for 0.5 hour to separate the layers, separate 181kg of the lower high-salt mother liquor to the mother liquor tank, and put the remaining oil layer into the crystallizer. After the discharge, the upper surface of the material layer is at the same level as the bottom of the crystallizer overflow port, and the top of the overflow port is about 5cm higher than the overflow port.

[0067] 3) 45°C hot water is passed through the jacket of the crystallizer to crystallize the product (the melting point of the pure product is about 102°C, the melting point of N-cyanoethylaniline is about 52°C, and the melting point of N,N-dicyanoethylaniline is about 83°C).

[0068] 4) 75°C hot water is passed through the jacket and heating tube of the crystallizer to start sweating. When sweat is visibly produced, the hot water pump is turned on to pass the 75°C hot water preheated in the stratification kettle into the crystallizer from the bottom of the crystallizer, and the hot water flow rate is controlled at 420kg / h.

[0069] 5) Oily sweat can be seen on the surface of the solid material layer in the crystallizer. The upper layer of the sweat is hot water. The hot water and sweat flow into the stratification kettle from the overflow port of the crystallizer through the upper feed port of the stratification kettle. The fluid flows along the guide tube to the middle and lower end of the stratification kettle. After passing the lower end of the guide tube, the sweat sinks to the bottom of the cone of the stratification kettle and gathers. The hot water floats up and covers the water guide pipe of the stratification kettle.

[0070] 6) After sweating for 0.5 h, when no sweat is produced on the surface of the crystallizer material layer, sweating is stopped, and the crystals in the crystallizer and the sweat at the bottom of the layered kettle are taken to test the purity. The crystal purity (HPLC): N-cyanoethyl-N-benzylaniline 98.1%, N-ethylaniline 0.5%, N,N-dicyanoethylaniline 0.7%; the sweat purity (HPLC): N-cyanoethyl-N-benzylaniline 13.7%, N-ethylaniline 68.1%, N,N-dicyanoethylaniline 13.6%; the dry weight of sweat is 11.75 kg.

[0071] 7) Steam is introduced into the jacket and heating tube of the crystallizer, and the temperature is raised to 105° C. After the crystals are melted, they are placed in a crystallization kettle, 300 kg of water is added, the temperature is lowered for crystallization, and the product is filtered to obtain a needle-shaped N-cyanoethyl-N-benzylaniline solid product with a purity (HPLC): N-cyanoethyl-N-benzylaniline 98.6%, N-ethylaniline 0.2%, and N,N-dicyanoethylaniline 0.4%; the crystallization water jacket is used for reaction bottom water.

[0072] The N-cyanoethyl-N-benzylaniline product obtained in this example was used to synthesize a dye. The dye detection environmental protection indicators showed that the benzyl chloride content was 1.05 ppm and the dichlorotoluene content was 0.53 ppm, which met the oeko-texstandard 100 ecological and environmental protection standard; the dye detection application indicators were qualified.

[0073] Comparative Example 1:

[0074] 1) 160 kg of bottom water was added to the benzylation reactor, stirring was started, 120 kg of N-cyanoethylaniline, 96.7 kg of benzyl chloride and 41 kg of soda ash were added, the temperature was raised to 80°C and then the heating rate was reduced. According to the temperature runaway of the reaction, the temperature was evenly raised to 105-110°C within 7 hours. After the temperature was raised, the temperature was kept warm for 10 hours and samples were taken. The sample purity (HPLC) was: N-cyanoethyl-N-benzylaniline 92.5%, N-ethylaniline 4.2%, N,N-dicyanoethylaniline 1.5%, which was unqualified and not suitable for the next step 2). 3 kg of benzyl chloride and 0.5 kg of soda ash were added, and the temperature was kept warm for 2 hours and samples were taken. The N-cyanoethyl-N-benzylaniline was 93.5%, N-ethylaniline was 2.8%, and N,N-dicyanoethylaniline was 1.8%, which was qualified and the next step 2) was carried out.

[0075] 2) Add 300 kg of water to the benzylation reaction kettle, cool and crystallize, emulsify and filter, 493 kg of high-salt mother liquor enters the mother liquor tank, and the powdered product is sampled and tested for purity (HPLC): N-cyanoethyl-N-benzylaniline 94.0%, N-ethylaniline 2.4%, N,N-dicyanoethylaniline 1.6%.

[0076] 3) The product was washed with 350 kg of water, and the washing water jacket was used for reaction bottom water. After washing, samples were taken for purity testing (HPLC): N-cyanoethyl-N-benzylaniline 94.6%, N-ethylaniline 1.8%, N,N-dicyanoethylaniline 1.9%.

[0077] The N-cyanoethyl-N-benzylaniline product obtained in this comparative example 3) was used to synthesize dyes. The environmental protection indicators of the dye detection were 56.6 ppm for benzyl chloride and 15.4 ppm for dichlorotoluene, which did not meet the ecological and environmental protection standards of oeko-texstandard 100; the dye detection application indicators were unqualified.

[0078] Comparative Example 2:

[0079] 1) Add 160 kg of bottom water into the benzylation reactor, start stirring, add 120 kg of N-cyanoethylaniline, 118 kg of benzyl chloride, and 50 kg of soda ash. After adding, heat to 80 ° C and then reduce the heating rate. According to the temperature of the reaction, heat to 105-110 ° C evenly within 7 hours. After heating, keep the temperature for 10 hours and take samples. The purity of the samples (HPLC): N-cyanoethyl-N-benzylaniline 94.4%, N-ethylaniline 1.8%, N, N-dicyanoethylaniline 1.9%, qualified.

[0080] 2) Add 300 kg of water to the benzylation reaction kettle, cool and crystallize, emulsify and filter, 508 kg of high-salt mother liquor enters the mother liquor tank, and the powdered product is sampled and tested for purity (HPLC): N-cyanoethyl-N-benzylaniline 94.8%, N-ethylaniline 1.6%, N,N-dicyanoethylaniline 1.8%.

[0081] 3) The product was washed with 350 kg of water, and the washing water jacket was used for reaction bottom water. After washing, samples were taken for purity testing (HPLC): N-cyanoethyl-N-benzylaniline 95.0%, N-ethylaniline 1.4%, N,N-dicyanoethylaniline 1.9%.

[0082] The N-cyanoethyl-N-benzylaniline product obtained in this comparative example 3) was used to synthesize dyes. The environmental protection indicators of the dye detection were 1120 ppm for benzyl chloride content and 36.5 ppm for dichlorotoluene content, which did not meet the oeko-texstandard 100 ecological and environmental protection standards; the dye detection application indicators were unqualified.

[0083] In addition, it should be understood that after reading the above description of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. A production and purification device for N-cyanoethyl-N-benzylaniline, characterized in that: It includes a benzylation reaction kettle, a crystallizer, a crystallization kettle and a solid-liquid separation device; The benzylation reaction kettle is at least used for the reaction of N-cyanoethylaniline and benzyl chloride to obtain a crude N-cyanoethyl-N-benzylaniline product, and after the reaction is completed, acid is added to adjust the acidity and then allowed to stand for stratification to form a lower layer of mother liquor and an upper layer of oil liquid; The crystallizer is at least used to receive the upper oil liquid from the benzylation reaction kettle, and after receiving the upper oil liquid, sequentially performs cooling crystallization, heat preservation and sweating, and conducts out sweat and molten crystals; The crystallization kettle is at least used to receive the molten crystals from the crystallizer and add water to dilute and cool the crystals; The solid-liquid separation device is at least used for solid-liquid separation of the mixture obtained by cooling and crystallizing the crystallization kettle to obtain the purified N-cyanoethyl-N-benzylaniline solid.

2. The production and purification device according to claim 1, characterized in that: The crystallizer has a jacket, and a first heat exchange medium is contained in the jacket, and the first heat exchange medium is used at least for cooling crystallization and heat preservation and sweating; A heating tube is arranged in the crystallizer, and a second heat exchange medium is arranged in the heating tube, and the second heat exchange medium is used at least for heat preservation and sweating; The heating tubes are vertically distributed in the crystallizer.

3. The production and purification device according to claim 1, characterized in that: The production and purification device also includes a draft tube and a layered kettle; The bottom of the crystallizer is connected to a layering kettle; the layering kettle is at least used to introduce circulating water into the crystallizer through the bottom of the crystallizer to drain sweat; An overflow port is provided at the top of the crystallizer, and the overflow port is connected to a guide tube; the guide tube is at least used to receive the circulating water and sweat flowing out of the crystallizer through the overflow port, and guide the circulating water and sweat to the middle and lower part of the stratification kettle; The lower layer in the stratified kettle is sweat, and the upper layer is circulating water; A water guide pipe is arranged in the layered kettle corresponding to the circulating water layer, and the water guide pipe is connected to the bottom of the crystallizer. The layered kettle introduces circulating water into the crystallizer through the water guide pipe to guide out sweat.

4. A method for producing and purifying N-cyanoethyl-N-benzylaniline, characterized in that: Includes steps: S1, in a benzylation reaction kettle, N-cyanoethylaniline and benzyl chloride react to obtain a crude N-cyanoethyl-N-benzylaniline product; S2, adding acid to the benzylation reaction kettle to adjust to acidity and then letting it stand to separate into layers, and putting the upper layer of oil into a crystallizer; S3, cooling and crystallization in the crystallizer; S4, keeping warm in the crystallizer to sweat and drain out the sweat; S5, melting the crystals in the crystallizer, discharging them into a crystallization kettle, adding water, cooling and crystallizing, and performing solid-liquid separation to obtain the purified N-cyanoethyl-N-benzylaniline solid.

5. The production and purification method according to claim 4, characterized in that: In step S1: The molar ratio of N-cyanoethylaniline to benzyl chloride is 1:0.93-1. Further, the molar ratio of N-cyanoethylaniline to benzyl chloride is 1:x, 0.93≤x<1; The holding temperature of the reaction between N-cyanoethylaniline and benzyl chloride is 105-110°C; The reaction time of N-cyanoethylaniline and benzyl chloride at the insulation temperature is 2 to 10 hours; According to the HPLC test results, in the crude N-cyanoethyl-N-benzylaniline product, N-cyanoethylaniline ≤6%, N,N-dicyanoethylaniline ≤2%, N-cyanoethyl-N-benzylaniline ≥90%, and other impurities ≤2%.

6. The production and purification method according to claim 4, characterized in that: In step S2: The acid added to the benzylation reaction kettle includes one or more of sulfuric acid, hydrochloric acid, and acetic acid; The acidity is when the hydrogen ion concentration is 10 -5 ~1mol / L, preferably refers to a hydrogen ion concentration of 10 -4 ~10 -3 mol / L.

7. The production and purification method according to claim 4, characterized in that: In step S3, the crystallization temperature is lower than 52°C, preferably not higher than 50°C, and may further be 45-50°C.

8. The production and purification method according to claim 4, characterized in that: In step S4: The temperature for sweating is higher than 52°C and lower than 102°C, preferably 60-75°C; Using circulating water to drain sweat; the temperature of the circulating water is consistent with the temperature of the heat preservation sweating; The hourly flow rate of the circulating water is 0.5 to 3 times the mass of the crystals in the crystallizer.

9. The production and purification method according to claim 4, characterized in that: In step S5: The crystal water obtained by solid-liquid separation is used as the bottom water jacket in step S1; The purified N-cyanoethyl-N-benzylaniline solid is a powdery and / or needle-shaped product; The HPLC purity of the purified N-cyanoethyl-N-benzylaniline solid is ≥98%, and the HPLC detection result of N-cyanoethylaniline is ≤0.5%.

10. The production and purification method according to any one of claims 4 to 9, characterized in that: The production purification method uses the production purification device according to any one of claims 1 to 3.

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