A method and equipment for purifying benzylaminopurine

Abstract

The present invention relates to a benzylaminopurine purification method and purification equipment, which are used to solve the problem that the existing benzylaminopurine is difficult to be purified to more than 99%. The benzylaminopurine purification method comprises the following steps: step 1: adding a solvent to a benzylaminopurine crude product, wherein the mass ratio of the benzylaminopurine crude product to the solvent is 1:12-20, and stirring and dissolving; step 2: filtering the benzylaminopurine solution obtained in step 1 with a filtering device, standing, filtering after natural crystallization, washing with a solvent and drying, and obtaining a benzylaminopurine fine product with a purity of more than 99%.

Description

Technical Field

[0001] The invention relates to the technical field of purification, and in particular to a method and equipment for purifying benzylaminopurine. Background Art

[0002] Low-purity benzylaminopurine products have high impurity content, which will reduce the stability of benzylaminopurine. Moreover, as it is used as a pesticide, impurities enter the environment and cause pollution. Therefore, it is necessary to select high-purity benzylaminopurine technical to reduce the content of impurities in it to ensure agricultural safety production. At present, benzylaminopurine is mostly purified by filter paper filtration process, and the content of benzylaminopurine obtained can only be about 98%. It is very difficult to increase 0.1% above 98%. Summary of the invention

[0003] In view of the above analysis, the embodiment of the present invention aims to provide a method and a purification device for benzylaminopurine, so as to solve the problem that it is difficult to purify benzylaminopurine to more than 99%.

[0004] In one aspect, the present invention provides a method for purifying benzylaminopurine, comprising the following steps:

[0005] Step 1: adding a solvent to the crude benzylaminopurine product, wherein the mass ratio of the crude benzylaminopurine product to the solvent is 1:12-20, and stirring to dissolve;

[0006] Step 2: Filter the benzylaminopurine solution obtained in step 1 with a filtering device, let it stand, filter it after natural crystallization, wash it with a solvent and dry it to obtain a benzylaminopurine product with a purity of more than 99%.

[0007] Further, the solvent is alcohol;

[0008] The purity of the crude benzylaminopurine is 95% to 98%.

[0009] Furthermore, in the step 1, the temperature is raised to 74-77° C. and stirred to dissolve;

[0010] The stirring is performed by a frame stirring device at a stirring speed of 20 to 30 r / min.

[0011] Furthermore, in the step 2, the filtering device is an ultra-micro screening membrane filtering device;

[0012] The pore size of the filter membrane of the ultra-micro screening membrane filtration device is 0.1 μm.

[0013] Furthermore, the filter membrane is regenerated after being soaked in a dilute alkali solution for 4 to 7 hours;

[0014] The dilute alkali solution refers to a solution with a pH value of 10.5 to 11.5 and a concentration of 3 to 5%.

[0015] Furthermore, in the step 2, during the washing process, the volume ratio of the benzylaminopurine crystals to the solvent is 1:1.5, and washing is performed twice.

[0016] Furthermore, in the step 2, the drying temperature is 75±1°C.

[0017] On the other hand, the present invention provides a purification device for benzylaminopurine, which can at least be used to implement the above-mentioned purification method, and the purification device comprises a reaction tank, at least one filtering device, a crystallization tank and a filter cylinder connected in sequence;

[0018] The reaction tank is provided with a first inlet and a first outlet;

[0019] The filtering device is provided with a second inlet and a second outlet.

[0020] Furthermore, the filtering device is an ultrafine screening membrane filtering device, and the ultrafine screening membrane filtering device comprises:

[0021] a first cavity, communicating with the second inlet;

[0022] a second cavity, connected to the second outlet;

[0023] A plurality of filter elements are detachably disposed in the first cavity and connect the first cavity with the second cavity. The liquid to be filtered enters the first cavity through the second inlet, flows into the second cavity after being filtered by the filter element, and then is guided to the downstream device through the second outlet;

[0024] Preferably, the filtering device further comprises a housing and a partition plate located in the housing, wherein the partition plate divides the space in the housing into the first cavity and the second cavity;

[0025] The filter element is fixedly connected to the partition plate;

[0026] The partition plate is provided with a communication port, and the communication port is communicated with the fluid channel of the filter element;

[0027] The partition plate is further provided with the second inlet, and the second inlet extends to the outside of the shell through a liquid inlet pipe;

[0028] Preferably, a fixing plate is provided in the first cavity, and the fixing plate is provided with a fixing groove matched with the top end of the filter element;

[0029] The number of the fixing grooves, the communicating ports and the filter elements is the same;

[0030] The fixing groove is arranged opposite to the communication port, and limits the layout of the filter element in the first cavity;

[0031] Preferably, the shell includes an upper shell and a lower shell that are detachably arranged, the partition plate and the upper shell define the first cavity, and the partition plate and the lower shell define the second cavity.

[0032] Furthermore, the filter element comprises:

[0033] A filter housing is provided with a plurality of filter holes;

[0034] A filter membrane layer is located in the filter housing and is closely attached to the filter hole; the filter membrane layer encloses a fluid channel for filtrate to flow, and the fluid channel is connected to the second cavity;

[0035] Preferably, the filter membrane layer is an annular cylindrical filter layer formed by at least one layer of filter membrane;

[0036] Preferably, the filter membrane is a 0.1 μm microfiltration membrane;

[0037] Preferably, the microfiltration membrane is folded and arranged to form the filter membrane layer.

[0038] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0039] (1) It is possible to obtain higher quality and higher purity benzylaminopurine, with a purity of more than 99%, so as to meet the demand for high-purity benzylaminopurine products, and to further produce high-quality products to ensure the safe use of agricultural drugs;

[0040] (2) The purification process can save solvents and reduce the generation of hazardous wastes. Traditional purification processes mostly use dissolution filtration activated carbon adsorption processes. This process is an open operation, and the solvent evaporates into the air and the loss is large. In addition, the multiple steps are repeated, and the solvent loss is serious. At the same time, the hazardous waste activated carbon is not used and disposed of, causing certain harm to the environment. The present invention uses an ultra-fine screening membrane filtration device in the benzylaminopurine purification process, which can greatly overcome the above shortcomings. The production process is a closed operation, which can save more than 15% of solvent compared with the traditional process;

[0041] (3) The crystal size of the refined benzylaminopurine obtained by the present invention is significantly larger than the crystal size of the crude benzylaminopurine, so that the gaps between the benzylaminopurine crystals are increased, the wetting effect is better, and the dissolution efficiency of benzylaminopurine can be improved.

[0042] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0044] Figure 1 The chromatographic analysis results of the benzylaminopurine product obtained in Example 1 of the specific embodiment;

[0045] Figure 2 The chromatographic analysis results of the benzylaminopurine product obtained in Example 2 of the specific implementation method;

[0046] Figure 3 The chromatographic analysis results of the benzylaminopurine product obtained in Example 3 of the specific implementation method;

[0047] Figure 4 is the chromatographic analysis result of the benzylaminopurine standard in a specific embodiment;

[0048] Figure 5 This is a photo of the crude benzylaminopurine product under a microscope in Example 1 of the specific embodiment;

[0049] Figure 6 This is a photo of the benzylaminopurine product obtained in Example 1 under a microscope;

[0050] Figure 7 It is a structural schematic diagram of a purification device for benzylaminopurine in a specific embodiment;

[0051] Figure 8 It is a structural schematic diagram of an ultra-micro screening membrane filtration device in a specific implementation manner;

[0052] Fig. 9 is a cross-sectional view of an ultramicro screening membrane filtration device in a specific implementation manner;

[0053] Fig.10 It is a structural schematic diagram of a partition plate in a specific implementation manner;

[0054] Fig.11 It is a structural schematic diagram of a fixing plate in a specific implementation manner;

[0055] Fig.12 It is a structural schematic diagram of the filter element in a specific implementation manner;

[0056] Fig.13 It is a cross-sectional view of the filter element in a specific implementation manner.

[0057] Reference numerals:

[0058] 1-reaction tank; 101-first inlet; 102-first outlet; 2-filter device; 201-second inlet; 202-second outlet; 2a-first pipeline; 2b-second pipeline; 2c-first valve; 2d-second valve; 21-first cavity; 22-second cavity; 23-filter element; 231-filter housing; 231a-filter hole; 232-filter membrane layer; 233-fluid channel; 234-threaded portion; 235-convex 24-shell; 241-upper shell; 242-lower shell; 243-flange; 25-partition plate; 251-connecting port; 26-fixing plate; 261-fixing groove; 262-vent; 27-pressure gauge; 28-liquid inlet pipe; 29-liquid outlet pipe; 3-crystallization tank; 31-agitator; 301-third inlet; 302-third outlet; 4-filter cylinder; 401-open port; 402-recovery port; 5-solvent pump. DETAILED DESCRIPTION

[0059] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0060] In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly specified and limited, the term "connected" should be understood in a broad sense, for example, it can be a fixed connection, or a detachable connection, or an integral connection, which can be a mechanical connection, or an electrical connection, which can be a direct connection, or can be indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0061] The terms "top", "bottom", "above", "lower", and "on" used throughout the description are relative to the relative positions of components of a device, such as the relative positions of the top and bottom substrates within a device. It is understood that devices are multifunctional regardless of their orientation in space.

[0062] The common working surface of the present invention can be a plane or a curved surface, can be inclined, or can be horizontal. For the convenience of description, the embodiment of the present invention is placed on a horizontal plane and used on the horizontal plane, and "high and low" and "up and down" are defined in this way.

[0063] Embodiment 1

[0064] This embodiment discloses a method for purifying benzylaminopurine, comprising the following steps:

[0065] Step 1: adding a solvent to the crude benzylaminopurine product, wherein the mass ratio of the crude benzylaminopurine product to the solvent is 1:12-20, and stirring to dissolve;

[0066] Step 2: Filter the benzylaminopurine solution obtained in step 1 with a filtering device, let it stand, filter it after natural crystallization, wash it with a solvent and dry it to obtain a benzylaminopurine product with a purity of more than 99%.

[0067] In the above purification method, the solvent is alcohol, preferably 95% industrial alcohol.

[0068] In the step 1:

[0069] The purity of the crude benzylaminopurine is 95% to 98%, and illustratively, the purity is 97.2%, 93.82%, and 96.7%;

[0070] To avoid the product from being damaged, the temperature is raised and stirred to increase the dissolution rate. Preferably, the temperature is raised to 74-77°C. If the temperature is too high, the alcohol will boil and evaporate, and if the temperature is too low, the dissolution will be slow.

[0071] Preferably, a frame-type stirring device is used for stirring and dissolving, and the stirring speed is 20 to 30 r / min. If the stirring is too fast, the alcohol will float up and down in the tank more, which will cause instability. If the stirring is too slow, the dissolution effect will be poor.

[0072] Preferably, 900-1000 L of alcohol is added to 50-55 kg of crude benzylaminopurine, the temperature is raised to 75° C., and the mixture is stirred and dissolved for 1.5 h to 2 h (until all the mixture is dissolved).

[0073] In the step 2:

[0074] The filter device is an ultrafine screening membrane filter device (see Example 2 for the specific structure), which can overcome the problem of serious solvent loss and save more than 15% of solvent compared with the traditional process. The principle of the ultrafine screening membrane filter device is that under the impetus of the pressure difference, the solvent and small solute particles in the raw material liquid pass through the membrane, while the large particle components are retained by the membrane to achieve the purpose of purifying the material. Preferably, the pore size of the filter membrane is 0.1μm. At room temperature, a 0.15-0.3Mpa solvent pump is used to transport the benzylaminopurine solution to the ultrafine screening membrane filter device, and 3 tons of material solution can be purified per hour. The filter membrane can be regenerated after being soaked in a dilute alkali solution. The dilute alkali solution refers to a solution with a pH value of 10.5-11.5 and a concentration of 3-5%. Specifically, the regeneration process: the filter membrane is soaked in a dilute alkali solution for 4-7h (preferably 6h) and then rinsed with deionized water to neutrality to achieve the regeneration of the filter membrane. Preferably, the dilute alkali solution is 3-5% liquid alkali (sodium hydroxide solution), pH=11.

[0075] Preferably, natural crystallization is performed after 48 hours of suction filtration;

[0076] Preferably, during the washing process, the volume ratio of the benzylaminopurine crystals to the solvent is 1:1.5, and the washing is performed twice. During the washing process, a small amount of benzylaminopurine crystals will be dissolved, and the solvent after washing will be recovered and used in the next batch of dissolved materials;

[0077] Preferably, the drying temperature is 75±1° C. Too high a temperature will damage the product, while too low a temperature will take a long time to dry, wasting energy.

[0078] Preferably, the benzylaminopurine solution obtained in step 1 is filtered by an ultrafine sieve membrane filtration device, allowed to stand, naturally crystallized for 48 hours, then filtered by suction, washed with a solvent, and dried at 75° C. to obtain a benzylaminopurine fine product;

[0079] It should be noted that the purity of the benzylaminopurine fine product is greater than 99%.

[0080] The benzylaminopurine solution obtained in step 1 is transported to the filtering device through a solvent pump. Preferably, a 0.15-0.3Mpa solvent pump is used to transport the benzylaminopurine solution to the filtering device.

[0081] The purification method of the present invention removes most of the impurities that cannot be filtered by filter paper or other filter materials, and obtains high-purity benzylaminopurine fine products. The solvent is recycled and reused, which saves solvent and reduces solvent consumption. The filter membrane of the ultra-micro screening membrane filtration device is regenerated after being soaked in a dilute alkali solution, thereby reducing the generation of hazardous waste.

[0082] [Example 1] Add 950L of alcohol to 50kg of crude benzylaminopurine (purity: 97.2%), heat to 74℃ and stir to dissolve for 1.5h, pump to ultrafine screening membrane filtration device for filtration, let stand, cool naturally and crystallize for 48h, then filter, wash with alcohol and dry at 75℃ to obtain 44.82kg of refined benzylaminopurine.

[0083] [Example 2] To 55 kg of crude benzylaminopurine (purity: 96.82%), add 1000 L of alcohol, heat to 75°C and stir to dissolve for 2 hours, then pump to an ultrafine screening membrane filtration device for filtration, let stand, cool and crystallize naturally for 48 hours, then filter by suction, wash with alcohol and dry at 75°C to obtain 48.93 kg of refined benzylaminopurine.

[0084] [Example 3] To 53 kg of crude benzylaminopurine (purity: 96.78%), add 1000 L of alcohol, heat to 75°C and stir to dissolve for 2 hours, then pump to an ultrafine screening membrane filtration device for filtration, let stand, cool and crystallize naturally for 48 hours, then filter by suction, wash with alcohol and dry at 76°C to obtain 47.36 kg of refined benzylaminopurine.

[0085] The benzylaminopurine fine product (hereinafter referred to as fine product) and the benzylaminopurine standard product (hereinafter referred to as standard product, the standard product is from Valent BioSciences, USA) obtained in the above example were measured using a chromatographic analyzer, and then the purity of the benzylaminopurine fine product obtained in the above example was calculated. The calculation results are shown in Table 1. From the calculation results in Table 1, it can be seen that the purity of the benzylaminopurine fine product obtained by the present invention is above 99%.

[0086] Chromatographic conditions: Waters 2487 liquid chromatograph was used; the chromatographic column was 250 mm in length, 4.6 mm in inner diameter, C18 filler type, 5 μm filler particle size, and room temperature; the mobile phase included methanol and 0.05% phosphoric acid water, the volume ratio of the two was 60:40, and the flow rate of the mobile phase was 1.0 mL / min; the injection volume was 10 μL; and the detection wavelength was 254 nm.

[0087] Figure 1 to Figure 3 These are the chromatographic analysis results of the benzylaminopurine products obtained in Examples 1 to 3, respectively. Figure 4 This is the chromatographic analysis result of benzylaminopurine standard.

[0088] The calculation formula is: Purity of fine product = (peak area of ​​fine product / peak area of ​​standard product) × (injection volume of standard product / injection volume of fine product) × purity of fine product

[0089] Table 1 Calculation table of purity of benzylaminopurine in the example

[0090]

[0091] Crystals of crude benzylaminopurine and the refined benzylaminopurine obtained by the present invention were observed under a microscope. Taking Example 1 as an example, Figure 5 This is a microscope photo of crude benzylaminopurine. Figure 6 This is a microscope photo of benzylaminopurine. The microscope is a NIKON Eclipse E100 biological microscope and the photo was taken at 40 times the magnification. Figure 5 and Figure 6 By comparison, it can be seen that the crystal size of the benzylaminopurine fine product obtained by the present invention is significantly larger than the crystal size of the benzylaminopurine crude product, so that the gaps between the benzylaminopurine crystals are increased, the wetting effect is better, and the dissolution efficiency of the benzylaminopurine can be improved.

[0092] Embodiment 2

[0093] This embodiment also discloses a purification device for benzylaminopurine (hereinafter referred to as purification device), such as Figure 7 to Figure 13 As shown, it can at least be used to implement the purification method described in Example 1, and the purification equipment includes a reaction tank 1, at least one filtering device 2, a crystallization tank 3 and a filter cylinder 4 connected in sequence;

[0094] The reaction tank 1 is provided with a first inlet 101 and a first outlet 102, and a rotor 11 is provided inside the reaction tank 1;

[0095] The filtering device 2 is provided with a second inlet 201 and a second outlet 202;

[0096] The crystallization tank 3 is provided with a third inlet 301 and a third outlet 302:

[0097] The filter cylinder 4 is provided with an opening 401 facing the third outlet 302 and a recovery port 402 .

[0098] When the number of the filtering device is one, the second inlet 201 is communicated with the first outlet 102 , and the second outlet 202 is communicated with the third inlet 301 .

[0099] When the number of the filtering devices is greater than or equal to two, the filtering devices 2 can be connected in series, the second inlet of the filtering device located in the first position is connected to the first outlet 102, and the second outlet of the filtering device located in the last position is connected to the third inlet 301; the filtering devices 2 can be partially in use and partially in standby, and the filtering devices 2 in use are connected in series, and the second inlet of the filtering device located in the first position in use is connected to the first outlet 102, and the second outlet of the filtering device located in the last position in use is connected to the third inlet 301.

[0100] In this embodiment, there are two filtering devices, and the two filtering devices 2 can be connected in series to the purification process of the purification equipment, or only one of them can be located in the purification process, and the other one is used as a backup. Specifically, the second outlet 202 of the filtering device 2 located upstream is connected to the second inlet 201 and the third inlet 301 of the filtering device 2 located downstream through the first pipeline 2a and the second pipeline 2b, respectively, and the second outlet 202 of the filtering device 2 located downstream is connected to the second pipeline 2b. The first pipeline 2a and the second pipeline 2b are respectively provided with a first valve 2c and a second valve 2d for controlling the opening and closing of the pipelines, and the second valve 2d is located between the junction of the first pipeline 2a and the second pipeline 2b and the second outlet 202 of the downstream filtering device 2, so that the first valve 2c and the second valve 2d are connected in parallel, as shown in FIG. Figure 7 As shown, by controlling the opening and closing states of the first valve 2c and the second valve 2d, the two filter devices are connected in series or in parallel (i.e., one filter device is used and the other is in standby). When the first valve 2c is opened and the second valve 2d is closed, the two filter devices 2 are connected in series to the purification process of the purification equipment; when the first valve 2c is closed and the second valve 2d is opened, the upstream filter device 2 is in the purification process of the purification equipment, and the downstream filter device 2 is in standby state.

[0101] The first valve 2c and the second valve 2d may be solenoid valves or manual valves, or valves with both electrical and mechanical control.

[0102] According to a preferred embodiment of the reaction tank, the rotor 11 in the reaction tank 1 is a frame-type agitator. Further preferably, the frame height of the frame-type agitator is not less than half of the height of the reaction tank 1 to ensure the stirring effect.

[0103] The reaction tank 1 is provided with at least one first inlet 101 , which is located at the top of the side wall of the reaction tank 1 and / or the top of the reaction tank 1 , and the first outlet 102 is located at the bottom of the reaction tank.

[0104] Preferably, the number of the first inlets 101 is two, namely a feed inlet and a liquid inlet, so that the crude benzylaminopurine product and the solvent can enter the reaction tank 1 through the feed inlet and the liquid inlet respectively, so that the crude benzylaminopurine product and the solvent can enter the reaction tank 1 at the same time. On the one hand, the mixing effect of the crude benzylaminopurine product and the solvent is improved, and the dissolution efficiency is improved; on the other hand, the feeding rate of the reaction tank 1 is increased, thereby improving the purification efficiency of the purification equipment.

[0105] In order to improve the dissolution efficiency of the crude benzylaminopurine in the reaction tank 1, the reaction tank 1 is provided with a temperature regulating component to regulate the temperature in the reaction tank 1. The temperature regulating component includes a heater and a temperature sensor, and the control panel of the heater is arranged on the outer wall of the reaction tank 1 or is separately arranged outside the reaction tank 1, so that the user can control the temperature in the reaction tank 1.

[0106] According to a preferred embodiment of the filtering device 2, the filtering device 2 is an ultrafine screening membrane filtering device, and the ultrafine screening membrane filtering device comprises:

[0107] The first cavity 21 is connected to the second inlet 201;

[0108] The second cavity 22 is communicated with the second outlet 202;

[0109] Multiple filter elements 23 are detachably arranged in the first cavity 21 and connect the first cavity 21 with the second cavity 22. The liquid to be filtered enters the first cavity 21 from the second inlet 201, flows into the second cavity 22 after being filtered by the filter element 23, and is then guided to the downstream device from the second outlet 202.

[0110] It should be noted that the first cavity 21 is connected to the second cavity 22 via the filter element 23 , that is, the liquid to be filtered in the first cavity 21 can enter the second cavity 22 only after being filtered by the filter element 23 .

[0111] According to a preferred embodiment of the filter element 23, the filter element 23 comprises:

[0112] The filter housing 231 is provided with a plurality of filter holes 231a, and the liquid to be filtered enters the filter element 23 through the filter holes 231a for filtering. Preferably, the filter holes 231a are provided on the side wall of the filter housing 231;

[0113] The filter membrane layer 232 is located in the filter housing 231 and is close to the filter hole 231a. The filter membrane layer 232 encloses a fluid channel 233 for the filtered liquid (i.e., filtrate) to circulate, and the fluid channel 233 is connected to the second cavity 22 to allow the filtrate to enter the second cavity 22.

[0114] Preferably, the central axis of the fluid channel 233 substantially coincides with the central axis of the filter housing 231 to ensure that the filtrate is quickly introduced into the second cavity 22 .

[0115] In this embodiment, the filter housing 231 is a cylinder with an open bottom, the top of the filter housing 231 is sealed, and the bottom opening of the filter housing 231 is connected to the fluid channel 233, so that the filtrate can flow into the second cavity 22 without obstruction. The filter holes 231a are evenly distributed on the side wall of the filter housing 231. Preferably, the area occupied by all the filter holes 231a on the filter housing 231 is more than one third of the area of ​​the side wall of the filter housing 231 to ensure the filtering efficiency of the filter element 23.

[0116] The filter membrane layer 232 is an annular cylindrical filter layer formed by at least one layer of filter membrane, preferably, the filter membrane is a 0.1 μm microfiltration membrane. Further preferably, the microfiltration membrane is folded to form the filter membrane layer 232, specifically, the microfiltration membrane is rectangular, and the rectangle is folded and connected end to end to form an annular cylindrical filter layer, and the denser the folding, the better the filtering effect.

[0117] The height of the filter membrane layer 232 is not less than the distance from the highest filter hole to the lowest filter hole on the filter housing 231 to ensure that all the liquid to be filtered passing through the filter holes is filtered by the filter membrane layer.

[0118] When the filter membrane layer 232 includes multiple filter membranes, the filter membranes are pressed together in a stacked manner and then surrounded to form the filter membrane layer 232 .

[0119] The filter membrane layer 232 is pressed against the inner wall of the filter housing 231. In order to improve the stability of the filter membrane layer 232 in the filter housing 231, the filter housing 231 is provided with a bracket for pressing and supporting the filter membrane layer 232.

[0120] For the convenience of operation, when the filter membrane is regenerated in a dilute alkaline solution, the entire filter element 23 is immersed in the dilute alkaline solution. After the immersion, the filter element is rinsed with deionized water until the rinse liquid is neutral to achieve the regeneration of the filter membrane. Therefore, the material of the filter housing 231 is an alkali-resistant material. Preferably, the material of the filter housing 231 is plastic, which is not only light and convenient to operate, but also corrosion-resistant. Further preferably, the material of the filter housing 231 is polytetrafluoroethylene. On the one hand, it has the characteristics of acid and alkali resistance, resistance to various organic solvents, is almost insoluble in all solvents, and has extremely high chemical stability; on the other hand, it has the characteristics of high temperature resistance and high physical stability; finally, it has an extremely low friction coefficient, can be used as a lubricant, and is extremely easy to clean.

[0121] The filtering device further includes a housing 24 and a partition plate 25 located in the housing 24 . The partition plate 25 divides the space in the housing 24 into a first cavity 21 and a second cavity 22 .

[0122] In order to prevent the liquid to be filtered from directly flowing into the second cavity 22 without being filtered, the partition plate 25 is sealedly connected to the inner wall of the housing 24 .

[0123] The partition plate 25 is used to fix the filter element 23, that is, the filter element 23 is fixedly connected to the partition plate 25, and the partition plate 25 is provided with the same number of communication ports 251 as the filter element 23, and the communication ports 251 are communicated with the fluid channel 233, so that the filtrate enters the second cavity 22 through the communication ports 251. Preferably, the communication ports 251 are connected with the fluid channel 233.

[0124] The partition plate 25 is also provided with a second inlet 201, which extends to the outside of the shell 24 through a liquid inlet pipe 28 and is connected to an upstream device or an upstream pipe. The liquid inlet pipe 28 is partially located in the second cavity 22 so as to be connected to the second inlet 201 on the partition plate 25, that is, a through hole is provided on the cavity wall of the second cavity 22 for the liquid inlet pipe 28 to pass through, and the liquid inlet pipe 28 is sealed and connected to the through hole.

[0125] The filter element 23 is detachably arranged on the communication port 251, and the bottom end of the filter element 23 is sealed and connected to the partition plate 25. Exemplarily, the filter element 23 and the communication port 251 are detachably connected by threaded connection, that is, the bottom end of the side wall of the filter element 23 is provided with a threaded portion 234, and the communication port 251 is provided with a thread that matches the threaded portion 234. It should be noted that the filter element 23 and the communication port 251 can also be connected by a detachable manner such as a snap connection or a buckle connection, and are not limited to a screw connection.

[0126] The liquid inlet pipe 28 is sealedly connected to the partition plate 25 to ensure that the liquid to be filtered enters the first cavity from the second inlet 201. Preferably, the liquid inlet pipe 28 is detachably arranged on the second inlet 201, illustratively, by a detachable connection method such as screw connection, clamping connection, buckling connection, etc.

[0127] The housing 24 is provided with a second outlet 202 communicating with the second cavity 22 . The second outlet 202 is connected to an upstream device or an upstream pipeline through a liquid outlet pipeline 29 .

[0128] Preferably, the first cavity 21 is located above the second cavity 22, and the second outlet 202 is located at the bottom of the housing 24, so that the filtrate enters the second cavity 22 and is guided to the downstream device.

[0129] The shell 24 is made of stainless steel.

[0130] To facilitate maintenance of the filtering device, the housing 24 includes a detachable upper housing 241 and a lower housing 242 , the partition plate 25 and the upper housing 241 define the first cavity 21 , and the partition plate 25 and the lower housing 242 define the second cavity 22 .

[0131] The lower shell 242 is provided with a second outlet 202 and a through hole for the liquid inlet pipe 28 to pass through.

[0132] In this embodiment, the upper shell 241 and the lower shell 242 are detachably connected via a flange 243. In actual application, the detachable connection method of the upper shell 241 and the lower shell 242 is not limited to the flange 243, and can also be a detachable connection method such as snap connection and buckle connection.

[0133] The upper shell 241 , the lower shell 242 , and the partition plate 25 are all sealed and connected to each other.

[0134] The partition plate 25 is detachably connected to the upper shell 241 and / or the lower shell 242 .

[0135] In order to improve the stability of the filter element 23 in the first cavity 21, a fixing plate 26 is provided in the first cavity 1, and a fixing groove 261 is provided on the fixing plate 26 to match the top of the filter element 23 (the fixing groove 261 here can be a groove with a groove bottom, or a hole without a groove bottom, as long as the top of the filter element 23 can be at least partially embedded). In this embodiment, a cross-shaped protrusion 235 is provided on the top of the filter element 23, and the shape of the fixing groove 261 matches the protrusion 235 to form a cross groove.

[0136] The number of the fixing grooves 261 and the filter element 23 is the same, and the fixing grooves 261 and the communication opening 251 are arranged opposite to each other, limiting the layout of the filter element 23 in the first cavity 21. Preferably, when the filter element 23 is located in the first cavity 21, the central axis of the filter element 23 is parallel to the central axis of the filter device.

[0137] In this embodiment, the number of the filter elements 23 is twelve, and the twelve fixed grooves 261 (or connecting openings 251) are equally divided into two groups to form isosceles triangles with two bases arranged oppositely, that is, a group of six fixed grooves 261 (or connecting openings 251) forms an isosceles triangle.

[0138] In order to ensure that the circulation of liquid and gas in the first cavity 21 is not affected by the fixing plate 26 , the fixing plate 26 is provided with a plurality of vents 262 . As many vents 262 as possible are provided without affecting the stability of the fixing plate 26 .

[0139] The fixing plate 26 is connected to the inner wall of the first cavity 21 .

[0140] Preferably, the partition plate 25 and the fixing plate 26 are perpendicular to the central axis of the filtering device.

[0141] The threaded portion 234 and the protrusion 235 are respectively disposed at the bottom end and the top end of the filter housing 231 .

[0142] In order to improve the filtration rate of the filtration device, the pressure in the first cavity 21 of the filtration device 2 is lower than the external pressure, at least lower than the pressure of the upstream device. The pressure difference between the first cavity 21 and the external or upstream device is 0.15-0.3Mpa, so as to ensure that the filtration device 2 can filter about 3 tons of material solution per hour.

[0143] The pressure difference can be formed by a vacuum device, a solvent pump, etc. In this embodiment, a solvent pump 5 is provided between the reaction tank 1 and the filtering device 2 , and the benzylaminopurine solution formed in the reaction tank 1 is transported to the filtering device 2 by the 0.15-0.3Mpa solvent pump 5 .

[0144] The filter device 2 is provided with a pressure gauge 27 for monitoring the pressure in the first cavity 21 to ensure the stability of the filter device 2 .

[0145] The filtrate filtered by the filter device 2 enters the crystallization tank 3 through the third inlet 301 for crystallization.

[0146] A stirrer 31 is provided in the crystallization can 3. Preferably, the stirrer 31 is a frame stirrer. Further preferably, the frame height of the frame stirrer is not less than half of the height of the crystallization can 3 to ensure the stirring effect.

[0147] After the filtrate is crystallized in the crystallization jar 3, the crystals enter the filter cylinder 4 through the third outlet 302 via the open port 401. The filter cylinder 4 includes a sieve plate and filter paper or filter cloth laid on the sieve plate. After negative pressure filtration and washing with a solvent, some impurities on the crystals are removed and then dried to obtain a benzylaminopurine product with a purity of more than 99%.

[0148] It should be noted that the third outlet 302 is connected to the open port 401 through a closed pipe (not shown in the figure) to prevent the solvent from volatilizing into the air and causing a large loss. In addition, multiple steps of repeated operations will cause serious solvent loss.

[0149] The liquid extracted from the filter cylinder 4 after solvent washing is recovered through the recovery port 402 and can be used for dissolving the solvent in the reaction tank 1, realizing multiple utilization of the solvent, which is more environmentally friendly. Preferably, the recovery port 402 is connected to the first inlet 101 through a pipeline to realize the recycling of the solvent in the purification equipment.

[0150] The purification equipment of the present invention can be used to purify benzylaminopurine of higher quality and higher purity, and the purity can reach more than 99%, so as to meet the demand for high-purity benzylaminopurine products, and can further produce high-quality products to ensure the safe use of agricultural drugs. In addition, the present invention adopts an ultra-micro screening membrane filtration device for filtration, and the production process is a closed operation, which can save more than 15% of solvent compared with the traditional process.

[0151] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for purifying benzylaminopurine, characterized in that, The following steps are involved: Step 1: adding a solvent to the crude benzylaminopurine product, wherein the mass ratio of the crude benzylaminopurine product to the solvent is 1:12-20, and stirring to dissolve; Step 2: Filter the benzylaminopurine solution obtained in step 1 with a filter device, let it stand, filter it after natural crystallization, wash it with a solvent and dry it to obtain a benzylaminopurine product with a purity of more than 99%; Wherein, the filtering device is an ultra-micro screening membrane filtering device; The pore size of the filter membrane of the ultra-micro screening membrane filtration device is 0.1 μm; The solvent is alcohol.

2. The purification method according to claim 1, characterized in that The purity of the crude benzylaminopurine is 95% to 98%.

3. The purification method according to claim 1, characterized in that In the step 1, the temperature is raised to 74-77° C. and stirred to dissolve; The stirring is performed by a frame stirring device at a stirring speed of 20-30 r / min.

4. The purification method according to claim 1, characterized in that The filter membrane is regenerated after being soaked in a dilute alkali solution for 4 to 7 hours; The dilute alkali solution refers to a solution with a pH value of 10.5-11.5 and a concentration of 3-5%.

5. The purification method according to claim 1, characterized in that: In the step 2, during the washing process, the volume ratio of the benzylaminopurine crystals to the solvent is 1:1.5, and washing is performed twice.

6. The purification method according to claim 1, characterized in that: In the step 2, the drying temperature is 75±1°C.

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