A method and apparatus for preparing 4-chloro-3-hydroxybutyric acid ethyl ester

Abstract

The application discloses a preparation method and a preparation device of 4-chloro-3-hydroxybutyric acid ethyl ester. The preparation method comprises the following steps: preparing hydrogen chloride ethanol solution in a water bath reactor; adding 4-chloro-3-hydroxybutyric acid nitrile and carrying out acidolysis reaction; continuously injecting hydrogen chloride gas at a predetermined temperature, and reacting for a predetermined time; reducing pressure and removing hydrogen chloride and ethanol; adding ethanol for cooling, filtering out salt, and obtaining 4-chloro-3-hydroxybutyric acid ethyl ester ethanol solution; and then reducing pressure, distilling ethanol, and obtaining 4-chloro-3-hydroxybutyric acid ethyl ester product. The preparation device comprises a water bath kettle and a water bath reactor, an annular reaction cavity is formed between an inner cylinder and an outer cylinder of the water bath reactor, a lower part of a slow flow refiner extends into the annular reaction cavity and is in the inner cylinder, and a gas pumping system and a material feeding and discharging system are installed on a fixing frame. The application has the advantages of simple purification treatment steps, accurate control of reaction temperature, reduced safety risk, and no waste water generated. The application is suitable for the preparation of 4-chloro-3-hydroxybutyric acid ethyl ester.

Description

Technical Field

[0001] This invention belongs to the field of pharmaceutical intermediate preparation, specifically, it relates to a method and apparatus for preparing ethyl 4-chloro-3-hydroxybutyrate. Background Technology

[0002] Ethyl 4-chloro-3-hydroxybutyrate is an important intermediate, a key intermediate in the preparation of piracetam, and also used in the production of atorvastatin, L-carnitine, and other drug intermediates, possessing a very broad market. Currently, there are two main methods for preparing ethyl 4-chloro-3-hydroxybutyrate. The first method uses 4-chloro-3-hydroxybutyronitrile as a raw material, adds ethanol and sulfuric acid, and after acidolysis, neutralizes with an alkaline solution, centrifuges to remove salt, distills off the ethanol, extracts with an organic solvent and water, concentrates the organic phase to obtain crude ethyl 4-chloro-3-hydroxybutyrate, and then distills to obtain the final product, ethyl 4-chloro-3-hydroxybutyrate. This method is cumbersome, involves a large system, generates a large amount of wastewater containing salt and organic matter, and has a low yield. The second method involves using ethyl 4-chloroacetoacetate as a raw material, adding ethanol as a solvent, and sodium borohydride as a reducing agent to carry out the reaction. After the reaction is completed, the mixture is filtered, washed with water, and concentrated to obtain ethyl 4-chloro-3-hydroxybutyrate. This method uses expensive raw materials, has high costs, and generates wastewater and hazardous solid waste. Summary of the Invention

[0003] This invention provides a method and apparatus for preparing ethyl 4-chloro-3-hydroxybutyrate, which simplifies the purification process, effectively and accurately controls the reaction temperature, avoids the use of multiple organic solvents, reduces safety risks, simplifies subsequent processing, and is low in investment, low in cost, easy to operate, does not generate wastewater, and is environmentally friendly.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for preparing ethyl 4-chloro-3-hydroxybutyrate includes the following steps: S1. Add ethanol and catalyst to the water bath reactor, raise the temperature of the water bath reactor to 25-35℃, and introduce a predetermined amount of hydrogen chloride gas into the lower part of the water bath reactor through a slow flow refiner. Both the slow flow refiner and the water bath reactor are immersed in the water bath. S2. Control the gas extraction system to connect the gas extraction system to the upper and lower parts of the water bath reactor, so that the hydrogen chloride gas that is not dissolved in ethanol is extracted and forced to enter the water bath reactor from the lower part until the desired hydrogen chloride ethanol solution is prepared. S3. Then, a predetermined amount of 4-chloro-3-hydroxybutyronitrile is added to a water bath reactor through a slow-flow refiner, so that 4-chloro-3-hydroxybutyronitrile undergoes acid hydrolysis in a hydrogen chloride ethanol solution. S4. By heating the water bath, the temperature inside the water bath reactor is raised to 40-45℃. Hydrogen chloride is then continuously introduced into the water bath reactor through the slow-flow refiner, and the temperature is maintained at 40-45℃ for 3-4 hours. S5. When the residual raw material is less than 0.1%, the reaction is stopped, and the gas extraction system connects the upper part of the water bath reactor to the outside to depressurize the water bath reactor and carry out dehydrochlorination and deethanolification operations. First, hydrogen chloride is distilled out, and the gas extraction system connects the upper part of the water bath reactor to the first collection tank, where hydrogen chloride gas is collected. Then, ethanol is distilled out, and the gas extraction system connects the upper part of the water bath reactor to the second collection tank, where ethanol gas is collected. S6. Then, add ethanol to cool down, and then perform filtration to remove the by-product salt, to obtain an ethanol solution of ethyl 4-chloro-3-hydroxybutyrate. S7. Reduce the pressure in the water bath reactor to distill off the ethanol, ultimately yielding ethyl 4-chloro-3-hydroxybutyrate.

[0005] Further, the catalyst is pure water, and in step S1, the mass ratio of 4-chloro-3-hydroxybutyronitrile, hydrogen chloride and ethanol is 4-chloro-3-hydroxybutyronitrile:hydrogen chloride:ethanol = 1:1:2.

[0006] The present invention also discloses a preparation apparatus based on the above-mentioned preparation method of ethyl 4-chloro-3-hydroxybutyrate, comprising a water bath reactor assembled in a water bath and immersed in water, the water bath reactor having an inner cylinder and an outer cylinder with coincident axes, the lower ends of the inner cylinder and the outer cylinder being closed, the upper ends of the two being closed by annular end caps, and forming an annular reaction chamber between the inner cylinder and the outer cylinder, a slow-flow refiner extending from top to bottom along the axis of the inner cylinder, and the lower part of the slow-flow refiner extending into the annular reaction chamber, and the lower part of the slow-flow refiner being rotatably connected to the inner cylinder, a gas extraction system and a material supply and discharge system being installed on a fixed frame on the water bath, and the gas extraction system being connected to the annular reaction chamber, and the material supply and discharge system being connected to the slow-flow refiner.

[0007] Furthermore, the slow-flow refiner includes a guide tube that coincides with the axis of the inner cylinder. One end of the guide tube extends from the upper part of the inner cylinder to the lower part of the inner cylinder. Multiple slow-flow units are spaced apart on the guide tube along its extension direction. A distributor is constructed at the lower end of the guide tube. The distributor is fixedly connected to an annular refinement disk. The annular refinement disk is disposed at the lower part of the annular reaction chamber and rotatably connected to the inner cylinder. An upper flow channel and a lower flow channel are formed at the upper and lower ends of the guide tube, respectively. Adjacent slow-flow units are interconnected, and two slow-flow units located at the upper and lower ends of the guide tube are connected to the upper flow channel and the lower flow channel, respectively.

[0008] Furthermore, multiple arc-shaped slow-flow channels are uniformly constructed along the circumference of each of the slow-flow units. A direct current channel is formed at the slow-flow unit of the guide pipe, and a converging channel is formed between two adjacent slow-flow units in the guide pipe. The upper and lower ends of the direct current channel are respectively connected to the upper and lower ends of each arc-shaped slow-flow channel, and the direct current channel is connected to the converging channel.

[0009] Furthermore, the slow-flow unit includes a plurality of guide vanes evenly arranged along the axial direction of the guide pipe, and when the guide pipe is driven to rotate in the forward direction, the water in the inner cylinder moves upward in a swirling motion by the guide vanes, and each of the arc-shaped slow-flow channels is formed within the corresponding guide vane.

[0010] Furthermore, multiple buffer channels are constructed circumferentially on the guide pipe. Each buffer channel passes through a slow-flow unit in sequence along the vertical direction. The buffer channel includes multiple oblique flow channels arranged vertically in a staggered manner, forming the shape of a Tesla valve. A bend channel is constructed at the lower end of each oblique flow channel, and the lower end of the bend channel is connected to the upper end of the next oblique flow channel.

[0011] Furthermore, the equalizer includes an assembly cylinder constructed at and communicating with the lower end of the guide tube, a filter is assembled inside the assembly cylinder, and a lower end cap is installed at the lower end of the assembly cylinder; multiple connecting plates are uniformly connected around the assembly cylinder, and these connecting plates are connected to the annular refining disk, each connecting plate is constructed with a connecting channel, the connecting channel connecting the assembly cylinder and the space of the annular reaction chamber located below the annular refining disk.

[0012] Furthermore, the annular refining disk includes an annular disk body, a connecting sleeve is constructed on the inner wall of the annular disk body, the connecting sleeve is rotatably connected to the cylinder wall of the inner cylinder, a plurality of through holes are opened on the annular disk body, and a plurality of swirl blades are uniformly constructed along its circumference on the upper end surface of the annular disk body.

[0013] Furthermore, the gas extraction system includes a vertical drive component mounted on a fixed frame, a drive rod mounted at the output end of the vertical drive component, the lower end of the drive rod extending into the suction cylinder, and a piston constructed at the lower end of the drive rod. A first tube communicating with the upper end of the water bath reactor is constructed at the lower end of the suction cylinder, a second tube communicating with the first tube, and the second tube communicating with a third, fourth, fifth, and sixth tube respectively. The third tube communicating with the lower part of the annular reaction chamber, the fourth tube communicating with the first collection tank, the fifth tube communicating with the second collection tank, and the sixth tube communicating with... The pressure relief tank is connected, and control valves and gas check valves are respectively installed on the third, fourth, fifth, and sixth pipe bodies; the material supply and discharge system includes a pump body installed on a fixed frame, and a first connecting pipe and a second connecting pipe are respectively connected to the outlet and inlet ends of the pump body. The first connecting pipe and the second connecting pipe are connected through a guide pipe. The end of the first connecting pipe is constructed with a guide sleeve, which is rotatably connected and communicates with the slow-flow refiner. A first connector and a second connector are respectively constructed on the first connecting pipe and the second connecting pipe, and an on / off valve is respectively installed on the first connecting pipe, the guide pipe, the first connector, and the second connector.

[0014] The technological advancements achieved by this invention compared to existing technologies, due to the aforementioned structure, are as follows: In this invention, 4-chloro-3-hydroxybutyronitrile is reacted with hydrogen chloride in ethanol under a catalytic environment, maintaining reactivity and directly yielding ethyl 4-chloro-3-hydroxybutyrate. This process yields good results, is low-cost, and simplifies subsequent processing and operation. It avoids the use of multiple organic solvents, reducing input costs and safety risks. The recovered ethanol chloride can be recycled, and the byproduct salt is dried to obtain ammonium chloride, resulting in no wastewater generation. Furthermore, in the production process of ethyl 4-chloro-3-hydroxybutyrate, all... All reactions are completed within a water bath reactor. Since the water bath reactor consists of an inner and outer cylinder, when the reactor is submerged in the water bath, the water in the water bath is located in the space between the outer cylinder and the inner cylinder, thus facilitating sufficient heat transfer to the materials within the annular reaction chamber. Furthermore, to ensure that the temperature of the materials entering the annular reaction chamber reaches a predetermined temperature (consistent with the temperature inside the annular reaction chamber), the materials (gas or liquid) are supplied to a flow refiner through a material supply and discharge system. The flow refiner slows down the flow of the materials, reducing their velocity, and alternates between dispersed and converged flow, thereby facilitating heat exchange with the warm water located within the inner cylinder. The material temperature is adjusted to match the water bath temperature before entering the annular reaction chamber. Upon entering, the material is refined by a flow refiner and evenly distributed in the lower part of the chamber. As the flow refiner rotates, the refined material gradually rises, achieving sufficient contact and reaction with other materials in the annular reaction chamber, thus improving reaction efficiency. Furthermore, by adjusting the water temperature in the water bath, the temperature within the water bath reactor changes, and the pressure is reduced through a gas extraction system, facilitating the separate separation and collection of hydrogen chloride and ethanol, achieving the purpose of dehydrochlorination and deethanolination. During steps S2 and S4, the gas... The extraction system removes undissolved hydrogen chloride from the solution and then forces it into the lower part of the annular reaction chamber. This ensures that the hydrogen chloride ethanol solution and 4-chloro-3-hydroxybutyronitrile of the required concentration are fully acidified in the hydrogen chloride ethanol solution. Simultaneously, the gas extracted and forced into the annular reaction chamber is always in a water bath state, thus not affecting the temperature inside the annular reaction chamber. In summary, this invention simplifies the purification process, effectively and accurately controls the reaction temperature, avoids the use of multiple organic solvents, and reduces safety risks. Furthermore, subsequent processing is simple, and the invention features low investment, low cost, convenient operation, no wastewater generation, and environmental friendliness. Attached Figure Description

[0015] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0016] In the attached diagram: Figure 1 This is a schematic diagram of the preparation apparatus according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the preparation apparatus of the present invention after the water bath is removed; Figure 3 for Figure 2 A schematic diagram of the structure from another angle; Figure 4 for Figure 2 An axial structural cross-sectional view of the structure shown. Figure 5 for Figure 4 Enlarged view of the structure at part A in the middle; Figure 6 for Figure 4 Enlarged view of the structure of part B in the middle; Figure 7 for Figure 4 Enlarged view of the structure of part C in the middle; Figure 8 for Figure 4 Enlarged view of the structure of part D in the middle; Figure 9 This is a schematic diagram illustrating the flow of material vertically downward through a guide pipe and multiple slow-flow units into the annular reaction chamber, according to an embodiment of the present invention. Figure 10 This is a schematic diagram illustrating the material flowing vertically upward from the annular reaction chamber through a guide pipe and multiple slow-flow units in an embodiment of the present invention. Figure 11 This is a schematic diagram of the lower end cap and filter after being disassembled from the assembly cylinder according to an embodiment of the present invention; Figure 12 This is a partial cross-sectional view of the preparation apparatus of this invention after the water bath has been removed; Figure 13 This is a schematic diagram of the structure of the annular refining disc, assembly cylinder, guide tube, and multiple connecting plates connected according to an embodiment of the present invention; Figure 14 for Figure 13 The diagram shows a structural schematic from another angle.

[0017] Components labeled: 100-Water bath, 101-Drain connector, 102-Drain valve, 103-Support leg, 200-Water bath reactor, 201-Outer cylinder, 202-Inner cylinder, 203-Annular reaction chamber, 204-Feed chamber, 205-Connecting leg, 206-Annular end cap, 207-Inner water bath space, 300-Slow flow aerator, 301-Guide pipe, 302-Slow flow unit, 303-Guide hole, 304-Upper flow channel, 305-Direct flow channel, 306-Arc-shaped slow flow channel, 307-Confluence channel, 308-Lower flow channel, 309-Oblique flow channel, 310-Bend channel, 311-Annular disc, 312-Assembly cylinder, 313-Connecting plate, 314-Connecting channel, 315-Filter, 31 6-Slag discharge pipe, 317-Slag discharge valve, 318-Lower end cover, 319-Guide hole, 320-Swirl vane, 321-Connecting sleeve, 400-Drive motor, 500-Material supply and discharge system, 501-Pump body, 502-Second connecting pipe, 503-Second connector, 504-First connecting pipe, 505-First connector, 506-Guide pipe, 507-Guide sleeve, 508-Guide cavity, 600-Gas extraction system, 601-Drive cylinder, 602-Suction cylinder, 603-Drive rod, 604-Suction cavity, 605-Piston, 606-First pipe body, 607-Second pipe body, 608-Third pipe body, 609-Fourth pipe body, 610-Fifth pipe body, 611-Sixth pipe body, 612-Control valve, 700-Fixed bracket. Detailed Implementation

[0018] The preferred embodiments of the present invention will now be described with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0019] This invention discloses a method for preparing ethyl 4-chloro-3-hydroxybutyrate, comprising the following steps: S1. Add ethanol and catalyst to the water bath reactor 200, raise the temperature of the water bath reactor 200 to 25-35℃, and introduce a predetermined amount of hydrogen chloride gas into the lower part of the water bath reactor 200 through the slow flow refiner 300. Both the slow flow refiner 300 and the water bath reactor 200 are immersed in the water bath 100. S2. Control the gas extraction system 600 to connect the gas extraction system 600 with the upper and lower parts of the water bath reactor 200, so that the hydrogen chloride gas that is not dissolved in ethanol is extracted and forced to enter the water bath reactor 200 from the lower part until the desired hydrogen chloride ethanol solution is prepared. S3. Then, the predetermined amount of 4-chloro-3-hydroxybutyronitrile is added to the water bath reactor 200 through the slow flow refiner 300, so that 4-chloro-3-hydroxybutyronitrile undergoes acid hydrolysis in the hydrogen chloride ethanol solution. S4. By heating the water bath 100, the temperature inside the water bath reactor 200 is raised to 40-45℃. Hydrogen chloride is then introduced into the water bath reactor 200 through the slow-flow refiner 300, and the temperature is maintained at 40-45℃ for 3-4 hours. S5. When the residual raw material is less than 0.1%, the reaction is stopped, and the gas extraction system 600 connects the upper part of the water bath reactor 200 to the outside, depressurizing the water bath reactor 200 to perform dehydrochlorination and deethanolification operations. First, hydrogen chloride is distilled out, and the gas extraction system 600 connects the upper part of the water bath reactor 200 to the first collection tank, where the hydrogen chloride gas is collected. Then, ethanol is distilled out, and the gas extraction system 600 connects the upper part of the water bath reactor 200 to the second collection tank, where the ethanol gas is collected. S6. Then, add ethanol to cool down, and then perform filtration to remove the by-product salt, to obtain an ethanol solution of ethyl 4-chloro-3-hydroxybutyrate. S7. Reduce the pressure in the water bath reactor 200 to distill off the ethanol, ultimately obtaining ethyl 4-chloro-3-hydroxybutyrate.

[0020] The advantages of this invention are as follows: In this invention, 4-chloro-3-hydroxybutyronitrile is reacted with hydrogen chloride in ethanol under a catalyst environment to maintain the reaction activity and directly obtain ethyl 4-chloro-3-hydroxybutyrate. The yield is good, the cost is low, the subsequent processing is simple, and the operation is convenient. It avoids the use of multiple organic solvents, reduces input costs and safety risks, and the recovered hydrogen chloride ethanol can be recycled after the reaction is completed. The by-product salt is dried to obtain ammonium chloride as a by-product, and no wastewater is generated.

[0021] Example 1 Ethanol and catalyst were added to a water bath reactor 200, and hydrogen chloride gas was introduced at 25-35°C. Then 4-chloro-3-hydroxybutyronitrile was added and the mixture was kept at this temperature for 0.5 hours.

[0022] Of which, by weight parts: 200 ethanol Catalyst 15 Hydrogen chloride gas 80 4-Chloro-3-hydroxybutyronitrile 100 After completion, the temperature is raised to 40-45℃, and 20 parts by weight of hydrogen chloride is continuously passed through. The temperature is maintained at 40-45℃, and the reaction is carried out for 4 hours. When the residual raw material is less than 0.1%, the reaction is stopped. Hydrogen chloride and ethanol are recovered under reduced pressure, new ethanol is added, and the mixture is cooled and filtered to remove salt, yielding an ethanol solution of ethyl 4-chloro-3-hydroxybutyrate. The ethanol is evaporated under reduced pressure at 45℃ to dryness, yielding a pale yellow ethyl 4-chloro-3-hydroxybutyrate product with a weight of 130.5, a purity of 98.55%, and a yield of 93.62%.

[0023] Example 2 Ethanol and catalyst were added to a water bath reactor 200, and hydrogen chloride gas was introduced at 25-35°C. Then 4-chloro-3-hydroxybutyronitrile was added and the mixture was kept at this temperature for 0.5 hours.

[0024] Of which, by weight parts: 200 ethanol Catalyst 10 Hydrogen chloride gas 80 4-Chloro-3-hydroxybutyronitrile 100 After completion, the temperature was raised to 40-45℃, and 20 parts by weight of hydrogen chloride were continuously passed through. The temperature was maintained at 40-45℃, and the reaction was carried out for 4 hours. When the residual raw material was less than 0.1%, the reaction was stopped. Hydrogen chloride and ethanol were recovered under reduced pressure, new ethanol was added, and the mixture was cooled and filtered to remove salt, yielding an ethanol solution of ethyl 4-chloro-3-hydroxybutyrate. The ethanol was evaporated under reduced pressure at 45℃ to dryness, yielding a pale yellow ethyl 4-chloro-3-hydroxybutyrate product with a weight of 124.5 parts, a purity of 96.85%, and a yield of 89.31%.

[0025] Example 3 Ethanol and catalyst were added to a water bath reactor 200, and hydrogen chloride gas was introduced at 25-35°C. Then 4-chloro-3-hydroxybutyronitrile was added and the mixture was kept at this temperature for 0.5 hours.

[0026] Of which, by weight parts: 200 ethanol Catalyst 15 100g of hydrogen chloride gas 4-Chloro-3-hydroxybutyronitrile 100 After completion, the temperature was raised to 40-45℃, and 20 parts by weight of hydrogen chloride were continuously passed through. The temperature was maintained at 40-45℃, and the reaction was carried out for 4 hours. When the residual raw material was less than 0.1%, the reaction was stopped. Hydrogen chloride and ethanol were recovered under reduced pressure, new ethanol was added, and the mixture was cooled and filtered to remove salt, yielding an ethanol solution of ethyl 4-chloro-3-hydroxybutyrate. The ethanol was evaporated under reduced pressure at 45℃ to dryness, yielding a pale yellow ethyl 4-chloro-3-hydroxybutyrate product with a weight of 130.6, a purity of 98.25%, and a yield of 93.69%.

[0027] Example 4 Ethanol and catalyst were added to a water bath reactor 200, and hydrogen chloride gas was introduced at 25-35°C. Then 4-chloro-3-hydroxybutyronitrile was added and the mixture was kept at this temperature for 0.5 hours.

[0028] Of which, by weight parts: 250 ethanol Catalyst 15 Hydrogen chloride gas 80 4-Chloro-3-hydroxybutyronitrile 100 After completion, the temperature was raised to 40-45℃, and 20 parts by weight of hydrogen chloride were continuously passed through. The temperature was maintained at 40-45℃, and the reaction was carried out for 4 hours. When the residual raw material was less than 0.1%, the reaction was stopped. Hydrogen chloride and ethanol were recovered under reduced pressure, new ethanol was added, and the mixture was cooled and filtered to remove salt, yielding an ethanol solution of ethyl 4-chloro-3-hydroxybutyrate. The ethanol was evaporated under reduced pressure at 45℃ to dryness, yielding a pale yellow ethyl 4-chloro-3-hydroxybutyrate product with a weight of 127.4 parts, a purity of 97.86%, and a yield of 91.39%.

[0029] In a preferred embodiment of the present invention, ethanol is both a reactant and a solvent, and hydrogen chloride gas is added as a supplement, which is subsequently recovered and reused without further treatment. The catalyst is pure water. In step S1, the mass ratio of 4-chloro-3-hydroxybutyronitrile, hydrogen chloride, and ethanol is 4-chloro-3-hydroxybutyronitrile:hydrogen chloride:ethanol = 1:1:2.

[0030] This invention also discloses a preparation apparatus based on the above-described method for preparing ethyl 4-chloro-3-hydroxybutyrate, such as... Figure 1-14As shown, the system includes a water bath 100, a water bath reactor 200, a slow-flow aerator 300, a gas extraction system 600, and a material supply and discharge system 500. The water bath reactor 200 is assembled inside the water bath 100 and is submerged in the water within the water bath 100. The water bath reactor 200 of this invention has an inner cylinder 202 and an outer cylinder 201 with coincident axes. The lower ends of the inner cylinder 202 and the outer cylinder 201 are closed, and their upper ends are closed by an annular end cap 206. An annular reaction chamber 203 is formed between the inner cylinder 202 and the outer cylinder 201, and the space inside the inner cylinder 202 is an inner water bath space 207. The slow-flow aerator 300 of this invention extends from top to bottom into the inner water bath space 207 along the axis of the inner cylinder 202. The lower part of the slow-flow aerator 300 extends into the annular reaction chamber 203, and the lower part of the slow-flow aerator 300 is rotatably connected to the inner cylinder 202. The gas extraction system 600 and the material supply and discharge system 500 of this invention are mounted on a fixing frame 700 on the water bath 100. The gas extraction system 600 is connected to the annular reaction chamber 203, and the material supply and discharge system 500 is connected to the slow-flow aerator 300. This invention provides multiple support legs 103 at the lower end of the water bath 100 to support it. A drain connector 101 is installed at the lower part of the water bath 100, and a drain valve 102 is installed on the drain connector 101. The water in the water bath 100 of this invention can be heated electrically, i.e., an electric heating wire is installed inside the water bath 100. This invention regulates the temperature within the annular reaction chamber 203 using a water bath, ensuring gentle temperature control and preventing adverse reactions caused by sudden temperature changes. The outer cylinder 201 has multiple connecting legs 205 circumferentially constructed at its lower end. These connecting legs 205 are all connected to the bottom wall of the water bath 100, and there are gaps between them to allow water to flow between the inner cylinder 202 and the outer cylinder 201.The working principle and advantages of this invention are as follows: In the production process of ethyl 4-chloro-3-hydroxybutyrate, all reactions are completed within a water bath reactor 200. Since the water bath reactor 200 is composed of an inner cylinder 202 and an outer cylinder 201, when the water bath reactor 200 is immersed in the water bath vessel 100, the water in the water bath vessel 100 is located in the space outside the outer cylinder 201 and inside the inner cylinder 202, thereby ensuring sufficient heat transfer to the material in the annular reaction chamber 203. Furthermore, to ensure that the temperature of the material entering the annular reaction chamber 203 reaches a predetermined level... The temperature (consistent with the temperature inside the annular reaction chamber 203) is maintained. Material (gas or liquid) is supplied to the slow-flow refiner 300 via the material supply and discharge system 500. The slow-flow refiner 300 slows the flow of the material, reducing its velocity and alternating between dispersion and merging. This allows the material to exchange heat with the warm water in the inner water bath space 207, equalizing the material's temperature with the water bath temperature. The material then enters the annular reaction chamber 203, where it is refined and evenly distributed in the lower part of the chamber. As the material is refined... As the reactor 300 rotates, the finely dispersed material gradually rises, achieving full contact and reaction with other materials in the annular reaction chamber 203, thus improving reaction efficiency. Furthermore, by adjusting the water temperature in the water bath 100, the temperature within the water bath reactor 200 changes, and the pressure is reduced via the gas extraction system 600, facilitating the separate separation and collection of hydrogen chloride and ethanol, achieving the purpose of dehydrochlorination and deethanolination. During steps S2 and S4, the gas extraction system 600 removes undissolved hydrogen chloride from the solution and then forcibly injects it into the annular reactor. The lower part of the annular reaction chamber 203 ensures that the hydrogen chloride ethanol solution and 4-chloro-3-hydroxybutyronitrile of the required concentration are fully acidified in the hydrogen chloride ethanol solution. At the same time, the gas extracted and forced into the annular reaction chamber 203 is always in a water bath state, thus not affecting the temperature inside the annular reaction chamber 203. In summary, the present invention simplifies the purification process, effectively and accurately controls the reaction temperature, avoids the use of multiple organic solvents, and reduces safety risks. Moreover, the subsequent treatment is simple, and it has the characteristics of low investment, low cost, convenient operation, no wastewater generation, and environmental friendliness.

[0031] As a preferred embodiment of the present invention, such as Figure 4As shown, the slow-flow refiner 300 includes a flow guide pipe 301, a distributor, an annular refining disk, and multiple slow-flow units 302. The flow guide pipe 301 coincides with the axis of the inner cylinder 202, and one end of the flow guide pipe 301 extends from the upper part of the inner cylinder 202 to the lower part of the inner cylinder 202. The aforementioned multiple slow-flow units 302 are spaced apart on the guide pipe 301 along its extension direction. A distributor is constructed at the lower end of the guide pipe 301 and is fixedly connected to an annular refining disc. The annular refining disc is located at the lower part of the annular reaction chamber 203 and divides the lower part of the annular reaction chamber 203 to form a feed chamber 204. The annular refining disc is rotatably connected to the inner cylinder 202. An upper flow channel 304 and a lower flow channel 308 are formed at the upper and lower ends of the guide pipe 301, respectively. Adjacent slow-flow units 302 are interconnected, and the two slow-flow units 302 located at the upper and lower ends of the guide pipe 301 are connected to the upper flow channel 304 and the lower flow channel 308, respectively. The working principle of this embodiment is as follows: The material (liquid or gas) flows from top to bottom through the guide pipe 301, driving the guide pipe 301 to rotate. During the flow through the guide pipe 301, the slow-flow unit 302 gradually slows down the material, causing the material to alternate between dispersion and merging. While slowing down, the material fully exchanges heat with the water in the water bath 100, so that the temperature of the material is the same as the temperature inside the annular reaction chamber 203 before entering it. After passing through the guide pipe 301, the material flows into the distributor, which distributes the material evenly and supplies it to the feed chamber 204 below the annular refining disc. The material passes through the feed chamber 204 and then is refined by the annular refining disc. As the annular refining disc rotates, the material is gradually evenly distributed in the annular reaction chamber 203 from bottom to top. Because the material is refined, the contact area between the materials is increased, promoting mutual reaction between the materials and thus improving the reaction efficiency. Furthermore, due to the slow flow of the slow flow unit 302, the material is preheated to the predetermined temperature, thus avoiding temperature changes in the annular reaction chamber 203 after the material enters the annular reaction chamber 203, which would affect the reaction effect.

[0032] As a preferred embodiment of the present invention, such as Figure 4 , 6As shown, multiple arc-shaped slow-flow channels 306 are constructed in each slow-flow unit 302. These arc-shaped slow-flow channels 306 are uniformly arranged along the circumference of the slow-flow unit 302. A direct current channel 305 is formed in the guide pipe 301 at the slow-flow unit 302, and a converging channel 307 is formed in the guide pipe 301 between two adjacent slow-flow units 302. The upper end of the direct current channel 305 is connected to the upper end of the corresponding arc-shaped slow-flow channel 306, and the lower end of the direct current channel 305 is connected to the lower end of the corresponding arc-shaped slow-flow channel 306. Moreover, the direct current channel 305 is connected to the converging channel 307. The working principle of this embodiment is as follows: The material enters through the guide pipe 301, then splits at the lower end of the upper flow channel 304 and enters the direct flow channel 305 and each arc-shaped slow flow channel 306 respectively. It converges again at the lower end of the direct flow channel 305. Since the lower outlet of the arc-shaped slow flow channel 306 in the figure is curved upward, the material exiting from the lower end of the arc-shaped slow flow channel 306 moves obliquely and obstructs the material exiting from the direct flow channel 305 to a certain extent, thus slowing down the material. It then converges and flows into the confluence channel 307, and then enters the direct flow channel 305 and arc-shaped slow flow channel 306 of the next slow flow unit 302. This flow continues until the material flows to the lower flow channel 308. In the whole process, the material is slowed down, split, and merged, so that the material can fully exchange heat with the water in the inner water bath space 207. During filtration or discharge, the material flows out of the slow-flow refiner 300 in the reverse direction through the annular reaction chamber 203. As it flows upward through the guide pipe 301, the lower end of the arc-shaped slow-flow channel 306 bends inward and upward, thus preventing the material from entering the arc-shaped slow-flow channel 306. In this way, the material passes through the lower flow channel 308, then through the alternating direct flow channel 305 and the confluence channel 307, and finally is discharged through the upper flow channel 304. Throughout the process, the loss of material flow rate is small, avoiding the impact on operation efficiency due to long filtration or discharge times.

[0033] As a preferred embodiment of the present invention, such as Figure 12As shown, the slow-flow unit 302 includes multiple guide vanes, which are uniformly arranged along the axial direction of the guide pipe 301. Each arc-shaped slow-flow channel 306 is constructed within the corresponding guide vane, thereby increasing the length of the arc-shaped slow-flow channel 306 and increasing the material travel distance, thus improving the heat exchange effect. Moreover, when the guide pipe 301 is driven to rotate forward, the water in the inner cylinder 202 is driven upward by the guide vanes, causing the water outside the outer cylinder 201 to be gradually guided to the inner water bath space 207. The water in the inner water bath space 207 flows upward and then flows from the upper end of the inner cylinder 202 to the outside of the outer cylinder 201, making the water in the water bath 100 circulate. This avoids heat loss caused by heat exchange between the water in the inner water bath space 207 and the material in the slow-flow refiner 300, which would prevent the material from being heated to the predetermined temperature. In this embodiment, a drive motor 400 is mounted on the fixed frame 700. The output shaft of the drive motor 400 is coaxially connected to the upper end of the guide pipe 301. The drive motor 400 drives the guide pipe 301 to rotate, thereby ensuring that the slow-flow refiner 300 rotates continuously as the material passes through it. Especially when the material enters the annular reaction chamber 203, the rotating slow-flow unit 302 can pull the water circulation in the water bath 100. At the same time, the annular refining disc rotates, and the finely refined material enters the annular reaction chamber 203. As the annular refining disc rotates, it swirls upward, improving the mixing and reaction efficiency.

[0034] As a preferred embodiment of the present invention, such as Figure 9-10 As shown, multiple buffer channels are constructed circumferentially in the guide pipe 301, and each buffer channel passes through a series of slow-flow units 302 in a vertical direction. The buffer channels include multiple vertically staggered oblique flow channels 309, forming a Tesla valve shape. A bend channel 310 is constructed at the lower end of each oblique flow channel 309, and the lower end of the bend channel 310 is connected to the upper end of the next oblique flow channel 309. The buffer channels in this embodiment adopt a Tesla valve design, utilizing its... Figure 9 Inlet flow obstruction, and such Figure 10 It features minimal loss of discharge flow rate. The purpose is to ensure sufficient heat exchange during feeding without affecting the discharge speed.

[0035] As a preferred embodiment of the present invention, such as Figure 4 , 7As shown in Figure 11, the distributor includes an assembly cylinder 312, which is constructed at the lower end of the guide pipe 301 and communicates with it. A filter 315 is assembled inside the assembly cylinder 312, and a slag discharge pipe 316 is constructed at the lower end of the filter 315. A slag discharge valve 317 is installed on the slag discharge pipe 316, and a lower end cover 318 is installed at the lower end of the assembly cylinder 312. The slag discharge pipe 316 extends beyond the lower end cover 318 and extends beyond the water bath 100, and the slag discharge valve 317 is located outside the water bath 100. In this embodiment, multiple connecting plates 313 are uniformly connected circumferentially around the assembly cylinder 312. These connecting plates 313 are connected to an annular refining disc, and each connecting plate 313 is constructed with a connecting channel 314, which communicates with the feed chamber 204. In this embodiment, the connecting plate 313 is configured as a guide vane. In this way, the assembly cylinder 312 and multiple connecting plates 313 form a guide impeller. During the process of the assembly cylinder 312 being driven to rotate in the forward direction, the guide impeller draws the water in the inner water bath space 207 upward. With the guidance of the slow flow unit 302, the purpose of multi-stage guidance of water in the inner water bath space 207 is achieved, thereby promoting the circulation of water in the water bath 100.

[0036] As a preferred embodiment of the present invention, such as Figure 13-14 As shown, the annular refining disc includes an annular disc body 311. A connecting sleeve 321 is constructed on the inner wall of the annular disc body 311, and the connecting sleeve 321 is rotatably connected to the cylinder wall of the inner cylinder 202. Multiple through holes 319 are provided on the annular disc body 311, and multiple swirling blades 320 are constructed on the upper end face of the annular disc body 311. These swirling blades 320 are uniformly arranged along the circumference of the annular disc body 311. The working principle of this embodiment is as follows: After the material enters the feed chamber 204, it is refined and evenly distributed to the lower part of the annular reaction chamber 203 through the through holes 319. During the rotation of the annular disc body 311, the swirling blades 320 draw the material in the annular reaction chamber 203 upwards, thereby allowing the refined material to fully mix and react with the material in the annular reaction chamber 203 from bottom to top, improving the reaction efficiency.

[0037] As a preferred embodiment of the present invention, such as Figure 2 , 4As shown in Figure 8, the gas extraction system 600 includes a vertical drive component, a suction cylinder 602, and a drive rod 603. The vertical drive component is a vertically positioned drive cylinder 601 with its cylinder rod facing upwards. The cylinder body is fixed to a mounting bracket 700. The upper end of the drive rod 603 is connected to the lower end of the cylinder rod, and the lower end of the drive rod 603 extends into the suction cylinder 602. A piston 605 is constructed at the lower end of the drive rod 603. A suction chamber 604 is formed within the suction cylinder 602, and the outer wall of the piston 605 is adapted to the inner wall of the suction chamber 604. In this embodiment, a first tube 606 is constructed at the lower end of the suction cylinder 602. The first tube 606 is connected to the upper end of the water bath reactor 200. A second tube 607 is connected to the first tube 606. The second tube 607 is connected to a third tube 608, a fourth tube 609, a fifth tube 610, and a sixth tube 611. The third tube 608 is connected to the lower part of the annular reaction chamber 203. The fourth tube 609 is connected to the first collection tank. The fifth tube 610 is connected to the second collection tank. The sixth tube 611 is connected to the pressure relief tank. A control valve 612 and a gas check valve are installed on the third tube 608, the fourth tube 609, the fifth tube 610, and the sixth tube 611, respectively. A check valve is also installed on the first tube 606. When hydrogen chloride gas is circulating, the control valves 612 on the fourth pipe 609, fifth pipe 610, and sixth pipe 611 are closed. Then, the drive cylinder 601 drives the drive rod 603 to reciprocate vertically. The hydrogen chloride gas in the annular reaction chamber 203 is drawn into the suction chamber 604, and then pushed into the lower part of the annular reaction chamber 203 through the third pipe 608, keeping the hydrogen chloride gas circulating within the annular reaction chamber 203 to promote the reaction. When it is necessary to depressurize the annular reaction chamber 203, the control valve 612 on the sixth pipe 611 is opened, and the control valves 612 on the other pipes are closed. Then, the drive cylinder 601 drives the drive rod 603 to reciprocate vertically. The gas in the annular reaction chamber 203 is drawn into the suction chamber 604, and then pushed into the pressure relief tank, thus achieving the purpose of depressurization. When hydrogen chloride gas needs to be discharged from the annular reaction chamber 203 after depressurization, the control valve 612 on the fourth pipe 609 is opened, while the control valves 612 on the other pipes are closed. Then, the drive cylinder 601 drives the drive rod 603 to reciprocate vertically, drawing the hydrogen chloride gas from the annular reaction chamber 203 into the suction chamber 604, and then pushing it into the first collection tank, thus collecting the hydrogen chloride gas. When ethanol gas needs to be discharged from the annular reaction chamber 203 after depressurization, the control valve 612 on the fifth pipe 610 is opened, while the control valves 612 on the other pipes are closed. Then, the drive cylinder 601 drives the drive rod 603 to reciprocate vertically, drawing the ethanol gas from the annular reaction chamber 203 into the suction chamber 604, and then pushing it into the second collection tank, thus collecting the ethanol gas.

[0038] As a preferred embodiment of the present invention, such as Figure 2-3 As shown in Figure 5, the material supply and discharge system 500 includes a pump body 501 mounted on a fixed frame 700. A first connecting pipe 504 and a second connecting pipe 502 are connected to the outlet and inlet ends of the pump body 501, respectively. The first connecting pipe 504 and the second connecting pipe 502 are connected through a guide pipe 506. A guide sleeve 507 is constructed at the end of the first connecting pipe 504. The guide sleeve 507 has a guide cavity 508. The guide sleeve 507 is fitted onto the upper part of the guide pipe 301 and is rotatably connected to the guide pipe 301. Multiple guide holes 303 are opened in the part of the guide pipe 301 located inside the guide sleeve 507 to realize the communication between the guide pipe 301 and the guide sleeve 507. In this embodiment, a first connector 505 and a second connector 503 are constructed on the first connecting pipe 504 and the second connecting pipe 502, respectively. On / off valves are installed on the first connecting pipe 504, the guide pipe 506, the first connector 505, and the second connector 503, respectively. When gaseous material needs to be supplied to the annular reaction chamber 203, the on / off valves on the first connector 505 and the first connecting pipe 504 are opened. The first connector 505 is connected to the gaseous material source, and the pressure of the gaseous material source is much higher than the pressure inside the annular reaction chamber 203. Therefore, under the pressure difference, the gaseous material smoothly enters the annular reaction chamber 203 through the slow-flow refiner 300. When liquid material needs to be added to the annular reaction chamber 203, the on / off valves on the second connector 503 and the first connecting pipe 504 are opened. The second connector 503 is connected to the liquid material source. Under the action of the pump body 501, the liquid material is pumped into the slow-flow refiner 300, and then enters the lower part of the annular reaction chamber 203. When filtering of byproduct salts is required, the on / off valves on the connecting pipe 506 and the first connector 505 are opened, and the first connector 505 is connected to the lower part of the annular reaction chamber 203. The reactants in the annular reaction chamber 203 flow through the slow-flow refiner 300 and then through a short section of the first connecting pipe 504. After that, they enter the pump body 501 through the connecting pipe 506 and the second connecting pipe 502, and finally flow back to the annular reaction chamber 203 through the other end of the first connecting pipe 504 and the first connector 505. When it is necessary to remove the product from the annular reaction chamber 203, the on / off valves on the connecting pipe 506 and the first connector 505 are opened, and the first connector 505 is connected to the product collection tank. The product is removed and collected in the collection tank.

[0039] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. An apparatus for preparing ethyl 4-chloro-3-hydroxybutyrate, characterized in that: The reactor includes a water bath reactor assembled inside a water bath and submerged in water. The water bath reactor has an inner cylinder and an outer cylinder with coincident axes. The lower ends of the inner and outer cylinders are closed, and their upper ends are closed by annular end caps, forming an annular reaction chamber between the inner and outer cylinders. A flow refiner extends from top to bottom along the axis of the inner cylinder, with its lower part extending into the annular reaction chamber and rotatably connected to the inner cylinder. A gas extraction system and a material supply and discharge system are installed. The gas extraction system is connected to the annular reaction chamber, and the material supply and discharge system is connected to the slow-flow refiner, which is mounted on a fixed frame on the water bath. The slow-flow refiner includes a guide pipe that coincides with the axis of the inner cylinder. One end of the guide pipe extends from the upper part to the lower part of the inner cylinder. Multiple slow-flow units are spaced apart on the guide pipe along its extension direction. A distributor is constructed at the lower end of the guide pipe. The distributor is fixedly connected to the annular refiner disc, which is located in the annular reaction chamber. The lower part is rotatably connected to the inner cylinder. An upper flow channel and a lower flow channel are formed at the upper and lower ends of the guide pipe, respectively. Adjacent flow-slowing units are interconnected, and two flow-slowing units located at the upper and lower ends of the guide pipe are connected to the upper flow channel and the lower flow channel, respectively. Multiple arc-shaped flow-slowing channels are uniformly constructed along the circumference of each flow-slowing unit. A direct flow channel is formed at the flow-slowing unit of the guide pipe, and a confluence channel is formed between two adjacent flow-slowing units in the guide pipe. The upper and lower ends of the direct flow channel are connected to the upper and lower ends of each arc-shaped flow-slowing channel, and the direct flow channel is connected to the confluence channel. Multiple buffer channels are constructed along the circumference of the guide pipe. Each buffer channel passes through each flow-slowing unit in sequence along the vertical direction. The buffer channel includes multiple oblique flow channels arranged vertically and forming the shape of a Tesla valve. A bend channel is constructed at the lower end of each oblique flow channel, and the lower end of the bend channel is connected to the upper end of the next oblique flow channel.

2. The apparatus for preparing ethyl 4-chloro-3-hydroxybutyrate according to claim 1, characterized in that: The slow-flow unit includes multiple guide vanes evenly arranged along the axial direction of the guide pipe. When the guide pipe is driven to rotate in the forward direction, the water in the inner cylinder moves upward in a swirling motion by the guide vanes. Each arc-shaped slow-flow channel is constructed within the corresponding guide vane.

3. The apparatus for preparing ethyl 4-chloro-3-hydroxybutyrate according to claim 1, characterized in that: The equalizer includes an assembly cylinder constructed at and connected to the lower end of the guide tube, a filter is assembled inside the assembly cylinder, and a lower end cap is installed at the lower end of the assembly cylinder; multiple connecting plates are uniformly connected around the circumference of the assembly cylinder, and these connecting plates are connected to the annular refining disk, and each connecting plate is constructed with a connecting channel, the connecting channel connecting the assembly cylinder and the space of the annular reaction chamber located below the annular refining disk.

4. The apparatus for preparing ethyl 4-chloro-3-hydroxybutyrate according to claim 1, characterized in that: The annular refining disk includes an annular disk body, a connecting sleeve is constructed on the inner wall of the annular disk body, the connecting sleeve is rotatably connected to the cylinder wall of the inner cylinder, multiple through holes are opened on the annular disk body, and multiple swirl blades are uniformly constructed along its circumference on the upper end surface of the annular disk body.

5. The apparatus for preparing ethyl 4-chloro-3-hydroxybutyrate according to claim 1, characterized in that: The gas extraction system includes a vertical drive unit mounted on a fixed frame. A drive rod is installed at the output end of the vertical drive unit. The lower end of the drive rod extends into the suction cylinder, and a piston is constructed at the lower end of the drive rod. A first tube communicating with the upper end of the water bath reactor is constructed at the lower end of the suction cylinder. A second tube is connected to the first tube. The second tube is respectively connected to a third, fourth, fifth, and sixth tube. The third tube is connected to the lower part of the annular reaction chamber, the fourth tube is connected to the first collection tank, the fifth tube is connected to the second collection tank, and the sixth tube is connected to the pressure relief system. The tank is connected, and control valves and gas check valves are respectively installed on the third, fourth, fifth, and sixth pipes; the material supply and discharge system includes a pump body installed on a fixed frame, and a first connecting pipe and a second connecting pipe are respectively connected to the outlet and inlet ends of the pump body. The first connecting pipe and the second connecting pipe are connected through a guide pipe. The end of the first connecting pipe is constructed with a guide sleeve, which is rotatably connected and communicates with a slow-flow refiner. A first connector and a second connector are respectively constructed on the first connecting pipe and the second connecting pipe, and an on / off valve is respectively installed on the first connecting pipe, the guide pipe, the first connector, and the second connector.

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