A continuous production device and method of methyl cyanoacetate

Abstract

The application provides a continuous production device and method of methyl cyanoacetate, which comprises a feeding unit, a reaction unit and a post-treatment unit connected in sequence, the reaction unit comprises a tubular reactor, the lower part of the tubular reactor is provided with a methanol feeding port and a sodium cyanide feeding port, the top of the tubular reactor is provided with a methyl chloroacetate feeding port, and the bottom of the tubular reactor is provided with a methyl cyanoacetate crude product discharging port; the feeding unit comprises a methanol feeding device, a sodium cyanide feeding device and a methyl chloroacetate feeding device, and the methanol feeding device, the sodium cyanide feeding device and the methyl chloroacetate feeding device are connected with the methanol feeding port, the sodium cyanide feeding port and the methyl chloroacetate feeding port respectively. The tubular reactor is used for continuous production, compared with the traditional batch production mode of the reaction kettle, the problem of sodium cyanide solid feeding is solved, the occurrence of the reverse reaction is effectively inhibited, and the yield of methyl cyanoacetate is greatly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of methyl cyanoacetate preparation, and particularly to a continuous production device and method of methyl cyanoacetate. BACKGROUND

[0002] Methyl cyanoacetate is an intermediate product commonly used in the pharmaceutical, pigment, pesticide and other industries. For example, after being condensed with formaldehyde to form poly 2-cyanomethyl acrylate, it is depolymerized to form a-methyl cyanoacrylate, which is commonly known as 501 instant adhesive. It is also an organic synthesis raw material and a pharmaceutical dye intermediate, mainly used for manufacturing adhesives, methyl cyanoacrylate, vitamin B6, etc.

[0003] The traditional production method of methyl cyanoacetate is an intermittent production method, that is, after methyl alcohol and sodium cyanide are put into a reaction kettle, methyl chloroacetate is slowly added dropwise. After the dropwise addition is completed, heat preservation is carried out, and after the heat preservation is completed, the finished product is obtained after filtration and distillation. However, when this intermittent production method is used, it will cause long reaction time period, great process control difficulty, complicated operation, low utilization rate, small production, large factory building area and many other problems. SUMMARY

[0004] The present application discloses a continuous production device and method of methyl cyanoacetate, which solves the problems of long reaction time period, great process control difficulty, complicated operation, low utilization rate, small production and large factory building area caused by the traditional intermittent production method.

[0005] To solve the above technical problems, the present application specifically adopts the following technical solutions:

[0006] In a first aspect, a continuous production device of methyl cyanoacetate is provided, which comprises a feeding unit, a reaction unit and a post-treatment unit connected in sequence. The reaction unit comprises a tubular reactor, the lower part of the tubular reactor is provided with a methyl alcohol feeding port and a sodium cyanide feeding port, the top of the tubular reactor is provided with a methyl chloroacetate feeding port, and the bottom of the tubular reactor is provided with a methyl cyanoacetate crude product discharging port.

[0007] The feeding unit comprises a methyl alcohol feeding device, a sodium cyanide feeding device and a methyl chloroacetate feeding device, which are respectively connected with the methyl alcohol feeding port, the sodium cyanide feeding port and the methyl chloroacetate feeding port.

[0008] The post-treatment unit comprises a continuous flow centrifuge, a molecular still and a receiving tank. The methyl cyanoacetate crude product discharging port is connected with the top of the continuous flow centrifuge through a pipeline, the bottom of the continuous flow centrifuge is connected with the top of the molecular still through a pipeline, and the bottom of the molecular still is connected with the receiving tank through a pipeline.

[0009] Further, the post-processing unit further comprises a cyanide-containing wastewater intermediate tank, and the continuous flow centrifuge is connected to the cyanide-containing wastewater intermediate tank through a pipeline.

[0010] Further, the continuous production device further comprises a cooling system, and cooling water jackets are arranged on the tubular reactor, the continuous flow centrifuge, the molecular distiller and the receiving tank, and the cooling water jackets are connected to the cooling system, so that the reaction temperature of the materials in the tubular reactor, the continuous flow centrifuge and the molecular distiller can be conveniently controlled through the cooling system.

[0011] In a second aspect, the present application provides a continuous production method of methyl cyanoacetate, which is produced by using the above-mentioned continuous production device, and the continuous production method comprises the following steps:

[0012] In step one, methanol and a sodium cyanide solution are respectively fed into the tubular reactor from a methanol feeding port and a sodium cyanide feeding port arranged at the lower part of the tubular reactor, and methyl chloroacetate is fed into the tubular reactor from a methyl chloroacetate feeding port arranged at the top of the tubular reactor, and after the mixing reaction of the methanol, the sodium cyanide and the methyl chloroacetate in the tubular reactor, methyl cyanoacetate crude product is generated;

[0013] In step two, the methyl cyanoacetate crude product in step one is discharged from a methyl cyanoacetate crude product discharge port arranged at the bottom of the tubular reactor and enters the continuous flow centrifuge through a pipeline to be centrifuged, so as to obtain light phase liquid and heavy phase liquid after centrifugation;

[0014] In step three, the light phase liquid after centrifugation in step two is discharged from the bottom of the continuous flow centrifuge and enters the molecular distiller through a pipeline to be distilled, and the obtained methyl cyanoacetate product enters the receiving tank, while the heavy phase liquid after centrifugation is discharged from the continuous flow centrifuge and enters the cyanide-containing wastewater intermediate tank through a pipeline to be stored for subsequent wastewater treatment.

[0015] Further, the reaction temperature in the tubular reactor in step one is controlled to be 0-20℃, and the residence time is 0.5-10min.

[0016] Further, the molar ratio of the methyl chloroacetate to the sodium cyanide in step one is 1:1.05-1.3.

[0017] Further, in step one, the flow rate of the methanol is set to be 5-10mL / min, the flow rate of the sodium cyanide solution is set to be 15-25mL / min, and the flow rate of the methyl chloroacetate is set to be 5-10mL / min.

[0018] Further, the diameter of the tubular reactor in step one is 300-600mm, and the length-diameter ratio is 2-5:1.

[0019] Further, the centrifugal speed of the continuous flow centrifuge in step two is 10000-16000 rpm, the feeding flow rate is 1.5-2 L / min, the temperature is 10-20 DEG C, and the centrifugal time is not more than 30 min.

[0020] Further, the distillation temperature of the molecular distiller in step three is 60-80 DEG C, the vacuum degree is 5-10 Pa, the feeding amount is 5-10 kg / h, the material inlet temperature is 10-20 DEG C, and the material residence time is not more than 5 min.

[0021] Compared with the prior art, the present application has the following beneficial effects:

[0022] 1. The present application adopts continuous production, and the cyanacetic acid methyl ester produced after the reaction of the methyl chloroacetate and the sodium cyanide is rapidly separated from the water in the sodium cyanide, thereby avoiding long-time contact and reducing the occurrence of reverse reaction.

[0023] 2. The present application combines the tubular reactor, the continuous flow centrifuge and the molecular distiller, can realize the whole pipeline transfer of the material, effectively avoids the overflow and leakage of the cyan-containing material and the organic solvent, thereby realizing the continuous and automatic operation of the workshop, reducing the on-site operators and improving the overall production efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0024] The drawings accompanying the specification of the present application are used to provide further understanding of the present application, the illustrative embodiments of the present application and the description thereof are used to explain the present application, and do not constitute improper limitation on the present application. In the drawings:

[0025] Figure 1 It is a structure schematic view of the continuous production device of the embodiment of the present application.

[0026] Among them, the above drawings include the following reference signs:

[0027] 1. Feeding unit; 11, methyl alcohol feeding device; 12, sodium cyanide feeding device; 13, methyl chloroacetate feeding device; 2, reaction unit; 21, tubular reactor; 22, methyl alcohol feeding port; 23, sodium cyanide feeding port; 24, methyl chloroacetate feeding port; 25, crude methyl cyanacetic ester outlet; 3, post-treatment unit; 31, continuous flow centrifuge; 32, molecular distiller; 33, receiving tank; 34, cyan-containing wastewater intermediate tank. DETAILED DESCRIPTION

[0028] The specific content of the present application will be described in detail below in combination with the drawings and embodiments.

[0029] As Figure 1As shown, the present application provides a continuous production device of methyl cyanoacetate, which comprises a feeding unit 1, a reaction unit 2 and a post-treatment unit 3 connected in sequence, the reaction unit 2 comprises a tubular reactor 21, the lower part of the tubular reactor 21 is provided with a methanol feeding port 22 and a sodium cyanide feeding port 23, the top of the tubular reactor 21 is provided with a methyl chloroacetate feeding port 24, and the bottom of the tubular reactor 21 is provided with a methyl cyanoacetate crude product discharge port 25; the feeding unit 1 comprises a methanol feeding device 11, a sodium cyanide feeding device 12 and a methyl chloroacetate feeding device 13, and the methanol feeding device 11, the sodium cyanide feeding device 12 and the methyl chloroacetate feeding device 13 are respectively connected with the methanol feeding port 22, the sodium cyanide feeding port 23 and the methyl chloroacetate feeding port 24. By arranging the methanol feeding device 11, the sodium cyanide feeding device 12 and the methyl chloroacetate feeding device 13, the methanol, the sodium cyanide and the methyl chloroacetate can be continuously fed into the tubular reactor 21 according to a certain flow rate, so that the continuous production is realized; and the tubular reactor 21 is used for continuous production, compared with the traditional batch production mode of the reaction kettle, the problem of difficult feeding of sodium cyanide solid is solved, the contact time of water in the sodium cyanide solution with the methyl chloroacetate and the methyl cyanoacetate is greatly reduced, the occurrence of reverse reaction is effectively inhibited, and the yield of the methyl cyanoacetate is effectively improved.

[0030] As shown, Figure 1 The post-treatment unit 3 comprises a continuous flow centrifuge 31, a molecular still 32 and a receiving tank 33, the methyl cyanoacetate crude product discharge port 25 is connected with the top of the continuous flow centrifuge 31 through a pipeline, the bottom of the continuous flow centrifuge 31 is connected with the top of the molecular still 32 through a pipeline, and the bottom of the molecular still 32 is connected with the receiving tank 33 through a pipeline. By arranging the continuous flow centrifuge 31, the centrifugal filtration operation can be performed on the methyl cyanoacetate crude product obtained by the reaction of the tubular reactor 21, and the material can be continuously discharged while being centrifuged, so that the purpose of efficient continuous production is realized; by arranging the molecular still 32, the continuous distillation operation can be performed on the light phase liquid after the continuous flow centrifuge 31, so as to remove the methanol and water in the light phase liquid, and the purity of the methyl cyanoacetate is effectively improved.

[0031] As shown, Figure 1As shown, the post-treatment unit 3 further comprises a cyanide-containing wastewater intermediate tank 34, and the continuous flow centrifuge 31 is connected to the cyanide-containing wastewater intermediate tank 34 through a pipeline. The heavy phase liquid after centrifugation is discharged from the continuous flow centrifuge 31 and then enters the cyanide-containing wastewater intermediate tank 34 through the pipeline for centralized storage for subsequent wastewater treatment. In addition, the continuous production device in the present application further comprises a cooling system, and the tubular reactor 21, the continuous flow centrifuge 31, the molecular distiller 32 and the receiving tank 33 are all provided with cooling water jackets, which are connected to the cooling system, so as to facilitate the control of the reaction temperature of the materials in the tubular reactor 21, the continuous flow centrifuge 31 and the molecular distiller 32.

[0032] The method for producing methyl cyanoacetate by using the above continuous production device comprises the following steps:

[0033] In step one, methanol and sodium cyanide solution are respectively fed into the tubular reactor 21 from the methanol feeding port 22 and the sodium cyanide feeding port 23 located at the lower part of the tubular reactor 21, and methyl chloroacetate is fed into the tubular reactor 21 from the methyl chloroacetate feeding port 24 located at the top of the tubular reactor 21, so that the methanol, sodium cyanide and methyl chloroacetate are continuously fed into the tubular reactor 21 at a certain flow rate, and the methanol, sodium cyanide and methyl chloroacetate are mixed and reacted in the tubular reactor 21 to generate crude methyl cyanoacetate;

[0034] In step two, the crude methyl cyanoacetate in step one is discharged from the crude methyl cyanoacetate discharging port 25 located at the bottom of the tubular reactor 21 and then enters the continuous flow centrifuge 31 through a pipeline to be centrifuged, so as to obtain light phase liquid and heavy phase liquid after centrifugation;

[0035] In step three, the light phase liquid after centrifugation is discharged from the bottom of the continuous flow centrifuge 31 and then enters the molecular distiller 32 through a pipeline to be distilled, and the obtained methyl cyanoacetate product enters the receiving tank 33; and the heavy phase liquid after centrifugation is discharged from the continuous flow centrifuge 31 and then enters the cyanide-containing wastewater intermediate tank 34 through a pipeline for centralized storage for subsequent wastewater treatment. The product methyl cyanoacetate in the receiving tank 33 is quantitatively fed into the next process for use.

[0036] In order to maximize the yield of methyl cyanoacetate, in the continuous production process, the reaction temperature in the tubular reactor 21 is preferably controlled at 0-20℃, the residence time is 0.5-10min; the diameter of the tubular reactor 21 is 300-600mm, the length-diameter ratio is 2-5:1; the centrifugal speed of the continuous flow centrifuge 31 is preferably 10000-16000rpm, the sample flow rate is 1.5-2L / min, the temperature is 10-20℃, and the centrifugation time is not more than 30min; the distillation temperature of the molecular distiller 32 is preferably 60-80℃, the vacuum degree is 5-10Pa, the feed amount is 5-10kg / h, the material inlet temperature is 10-20℃, and the material residence time is not more than 5min; the molar ratio of methyl chloroacetate to sodium cyanide is 1:1.05-1.3, so that the sodium cyanide is slightly excessive, which is beneficial to improve the reaction yield and inhibit the occurrence of reverse reaction; the flow rate of methyl alcohol is set to 5-10mL / min, the flow rate of sodium cyanide solution is set to 15-25mL / min, and the flow rate of methyl chloroacetate is set to 5-10mL / min.

[0037] Overall, the continuous production device and production method of the present application have the following advantages:

[0038] The present application adopts continuous production, and the methyl cyanoacetate produced after the reaction of methyl chloroacetate and sodium cyanide is quickly separated from water in sodium cyanide, avoiding long-time contact and reducing the occurrence of reverse reaction. Compared with the traditional batch production mode of reaction kettle, the yield can reach more than 98%, effectively reducing the production cost; the present application combines the tubular reactor, continuous flow centrifuge and molecular distiller, which can realize the whole pipeline transfer of materials, effectively avoiding the overflow and leakage of cyanide-containing materials and organic solvents, so as to realize the continuous and automatic operation of the workshop, reduce the on-site operators, and improve the overall production efficiency.

[0039] Finally, it should be pointed out that the above examples are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced equivalently without departing from the purpose and scope of the present application, which should be covered in the scope of the claims of the present application.

Claims

1. A method for the continuous production of methyl cyanoacetate, characterized in that: The continuous production method comprises the following steps: Step one, methanol and sodium cyanide solution are respectively fed into the tubular reactor (21) from the methanol feeding port (22) and the sodium cyanide feeding port (23) located at the lower part of the tubular reactor (21), methyl chloroacetate is fed into the tubular reactor (21) from the methyl chloroacetate feeding port (24) located at the top of the tubular reactor (21), and the methanol, sodium cyanide and methyl chloroacetate are continuously fed into the tubular reactor (21) at a certain flow rate, after the mixing reaction of the methanol, sodium cyanide and methyl chloroacetate in the tubular reactor (21), methyl cyanoacetate crude product is generated; Step two, the methyl cyanoacetate crude product in step one is discharged from the methyl cyanoacetate crude product discharge port (25) located at the bottom of the tubular reactor (21) and enters the continuous flow centrifuge (31) through a pipeline to be centrifuged, and light phase liquid and heavy phase liquid after centrifugation are obtained; Step three, the light phase liquid after centrifugation in step two is discharged from the bottom of the continuous flow centrifuge (31) and enters the molecular still (32) through a pipeline to be distilled, and the obtained methyl cyanoacetate product enters the receiving tank (33); and the heavy phase liquid after centrifugation is discharged from the continuous flow centrifuge (31) and enters the cyanide-containing wastewater intermediate tank (34) through a pipeline to be stored for subsequent wastewater treatment; The device for the continuous production of methyl cyanoacetate comprises a feeding unit (1), a reaction unit (2) and a post-treatment unit (3) connected in sequence, wherein the reaction unit (2) comprises a tubular reactor (21), the lower part of the tubular reactor (21) is provided with a methanol feeding port (22) and a sodium cyanide feeding port (23), the top of the tubular reactor (21) is provided with a methyl chloroacetate feeding port (24), and the bottom of the tubular reactor (21) is provided with a methyl cyanoacetate crude product discharge port (25); The feeding unit (1) comprises a methanol feeding device (11), a sodium cyanide feeding device (12) and a methyl chloroacetate feeding device (13), and the methanol feeding device (11), the sodium cyanide feeding device (12) and the methyl chloroacetate feeding device (13) are respectively connected with the methanol feeding port (22), the sodium cyanide feeding port (23) and the methyl chloroacetate feeding port (24); The post-treatment unit (3) comprises a continuous flow centrifuge (31), a molecular still (32) and a receiving tank (33), the methyl cyanoacetate crude product discharge port (25) is connected with the top of the continuous flow centrifuge (31) through a pipeline, the bottom of the continuous flow centrifuge (31) is connected with the top of the molecular still (32) through a pipeline, and the bottom of the molecular still (32) is connected with the receiving tank (33) through a pipeline; The device further comprises a cooling system, and the tubular reactor (21), the continuous flow centrifuge (31), the molecular still (32) and the receiving tank (33) are all provided with cooling water jackets, the cooling water jackets are connected with the cooling system, and the reaction temperature of the materials in the tubular reactor (21), the continuous flow centrifuge (31) and the molecular still (32) can be conveniently controlled through the cooling system. ​ 2. The continuous production process of methyl cyanoacetate according to claim 1, characterized by: The reaction temperature in the pipe reactor (21) in step one is controlled at 0-20℃, and the residence time is 0.5-10 min.

3. The continuous production process of methyl cyanoacetate according to claim 1, characterized by: The molar ratio of methyl chloroacetate to sodium cyanide in step one is 1:1.05-1.

3.

4. The continuous production process of methyl cyanoacetate according to claim 1, characterized by: The flow rate of methyl alcohol in step one is set at 5-10 mL / min, the flow rate of sodium cyanide solution is set at 15-25 mL / min, and the flow rate of methyl chloroacetate is set at 5-10 mL / min.

5. The continuous production process of methyl cyanoacetate according to claim 1, characterized by: The diameter of the pipe reactor (21) in step one is 300-600 mm, and the length-diameter ratio is 2-5:

1.

6. The continuous production process of methyl cyanoacetate according to claim 1, characterized by: The centrifugal rotation speed of the continuous flow centrifuge (31) in step two is 10,000-16,000 rpm, the sample flow rate is 1.5-2 L / min, the temperature is 10-20℃, and the centrifugation time is not more than 30 min.

7. The continuous production process of methyl cyanoacetate according to claim 1, characterized by: The distillation temperature of the molecular distiller (32) in step three is 60-80℃, the vacuum degree is 5-10 Pa, the feed amount is 5-10 kg / h, the material inlet temperature is 10-20℃, and the material residence time is not more than 5 min.

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