Method for preparing 2, 2-bis (3-m-nitrobenzamide-4-hydroxyphenyl) hexafluoropropane by microchannel reactor

Abstract

The invention relates to a method for preparing 2, 2-bis (3-m-nitrobenzamide-4-hydroxyphenyl) hexafluoropropane by a microchannel reactor, which comprises the following steps: fully mixing and preheating 6FAP and ethylene glycol monobutyl ether to obtain a 6FAP solution, taking the 6FAP solution and a preheated acylating agent as two strands of materials, and enabling the 6FAP solution and the acylating agent to respectively enter the microchannel reactor for mixed reaction to obtain 2, 2-bis (3-m-nitrobenzamide-4-hydroxyphenyl) hexafluoropropane. A product obtained by the reaction flows out from an outlet of the reactor; according to the present invention, the synthesis route process is simple and easy to operate. Compared with the existing route for synthesizing 2, 2-bis (3-m-nitrobenzamide-4-hydroxyphenyl) hexafluoropropane, the method has the advantages of higher safety, fewer three wastes, higher environmental friendliness, lower production cost and higher yield, and is more suitable for industrial mass production.

Description

Technical Field

[0001] The invention relates to a method for preparing 2,2-bis(3-m-nitrobenzamide-4-hydroxyphenyl)hexafluoropropane by using a microchannel reactor, belonging to the technical field of organic synthesis. Background Art

[0002] Polyimide (PI) is an aromatic heterocyclic polymer compound with an imide chain link in its molecular structure. It is one of the most heat-resistant types of engineering plastics and is widely used in aviation, aerospace, microelectronics, nanotechnology, liquid crystal, laser and other fields. Polyimide is known as the top material of the polymer material pyramid and is also called "a problem solver". Some industry insiders even believe that "without polyimide, there would be no microelectronics technology today." In recent years, countries have listed the research, development and utilization of PI as one of the development priorities of new chemical materials in the 21st century. Polyimide, due to its outstanding characteristics in performance and synthesis, has great application prospects whether as a structural material or as a functional material.

[0003] 2,2-bis(3-m-nitrobenzamide-4-hydroxyphenyl)hexafluoropropane is one of the important raw materials for preparing photosensitive polyimide resins, and its synthesis route refers to patent document CN102549497A. The existing synthesis method of 2,2-bis(3-m-nitrobenzamide-4-hydroxyphenyl)hexafluoropropane is to obtain the product by amidation of 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane and m-nitrobenzoyl chloride. m-Nitrobenzoyl chloride is highly corrosive and can easily cause rust in production equipment, causing serious safety hazards. A large amount of wastewater will be generated in the actual production process, which does not conform to the green and environmentally friendly production concept. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides a method for preparing 2,2-bis(3-m-nitrobenzamide-4-hydroxyphenyl)hexafluoropropane using a microchannel reactor.

[0005] The present invention utilizes a continuous flow microchannel reactor and uses ethylene glycol butyl ether as a solvent to prepare 2,2-bis(3-m-nitrobenzamide-4-hydroxyphenyl)hexafluoropropane, and has simple operation, safe and controllable amination process, high yield, high production efficiency, and can realize continuous industrial batch production. The present invention has mild preparation conditions, low production cost, easy batch and large-scale production, strong universality, and has a good industrial production foundation and broad application prospects.

[0006] Terminology

[0007] 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane is referred to as 6FAP.

[0008] The specific technical solutions of the present invention are as follows:

[0009] A method for preparing 2,2-bis(3-m-nitrobenzamide-4-hydroxyphenyl)hexafluoropropane using a microchannel reactor, comprising:

[0010] (1) 6FAP and ethylene glycol butyl ether are fully mixed and preheated to obtain a 6FAP solution, and the 6FAP solution and the preheated acylating agent are used as two streams;

[0011] (2) controlling the flow rate of the materials by a metering pump, so that the 6FAP solution and the acylating agent are respectively pumped into the microchannel reactor for mixed reaction, and the product obtained by the reaction flows out from the outlet of the reactor;

[0012] (3) The material obtained from the outlet of the microchannel reactor is collected and post-processed to obtain pure 2,2-bis(3-nitrobenzamide-4-hydroxyphenyl)hexafluoropropane.

[0013] Preferably according to the present invention, in step (1), the mass of ethylene glycol butyl ether is 4 to 10 times the mass of 6FAP, and further preferably, the mass of ethylene glycol butyl ether is 4 to 7 times the mass of 6FAP.

[0014] Preferably according to the present invention, in step (1), the acylating agent is a mixture of m-nitrobenzoyl chloride and N-methylpyrrolidone, and the mass ratio of m-nitrobenzoyl chloride to N-methylpyrrolidone is 1:2.

[0015] Preferably according to the present invention, in step (1), the molar ratio of 6FAP to m-nitrobenzoyl chloride is 1:3-4.

[0016] Preferably according to the present invention, in step (1), the preheating temperature is 0 to 60°C, and more preferably, the preheating temperature is 10 to 30°C.

[0017] Preferably, according to the present invention, in step (2), the reaction temperature of the microchannel reactor is controlled by an external heat exchanger, the heat exchange medium is heat transfer oil, the reaction temperature is 10 to 70° C., and the reaction residence time is 5 to 180 s.

[0018] More preferably, the reaction temperature is 15-45° C., and the reaction residence time is 30-90 s.

[0019] Preferably according to the present invention, the microchannel reactor module is a direct-flow microchannel reactor or an enhanced mixing type continuous flow microchannel reactor, the cross-sectional shape of the direct-flow microchannel reactor is a circular ring, and the enhanced mixing type continuous flow microchannel reactor series module is composed of 5 Corning high-throughput microchannel reactors with heart-shaped channels connected in series.

[0020] Preferably according to the present invention, the direct-flow microchannel reactor and the enhanced mixing continuous flow microchannel reactor are made of any one of glass, metal element, alloy, ceramic, single crystal silicon, and fluorine-containing resin, and the hydraulic diameter of the channel is 0.5-5mm.

[0021] Preferably according to the present invention, the feed flow rate of 6FAP solution is 20-30 g / min, and the feed flow rate of acylating agent is 5-10 g / min.

[0022] The present invention controls the feed flow rate of 6FAP solution and the feed flow rate of acylating agent, thereby greatly improving the yield.

[0023] Preferably, in step (3), the post-treatment is sequentially precipitation filtration, metal ion removal, pure water purification, and drying, and the precipitation filtration is adding an alcohol solvent for precipitation and then filtering, the alcohol solvent is a methanol aqueous solution, the mass of the alcohol solvent is 3 to 6 times the mass of 6FAP, the precipitation temperature is 10 to 25°C, and the mass ratio of ethanol to water in the methanol aqueous solution is 1:1 to 3.

[0024] Further preferably, the metal ions are removed by adding a deionizing agent to the product obtained after filtration to remove the metal ions, and the deionizing agent is deionized formamide, and the mass of the deionized formamide is 5 to 10 times the mass of 6FAP.

[0025] More preferably, the product after pure water purification to remove metal ions is added with pure water for stirring, the mass of the pure water is 1 to 4 times the mass of 6FAP, and the number of times of pure water purification is 3 to 5 times.

[0026] More preferably, the drying is forced air drying at 70-90°C.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. The present invention adopts a microchannel reactor to carry out the reaction to prepare 2,2-bis(3-m-nitrobenzamide-4-hydroxyphenyl)hexafluoropropane. The characteristics of the microchannel reactor can quickly dissipate heat, the reaction is more uniform, the back mixing is extremely low, the by-products are few, the yield is high, and the reaction can be continuous, which is suitable for industrial production;

[0029] 2. The present invention adopts a microchannel reactor for reaction, which has rapid reaction and greatly shortens the reaction time; in addition, the heat transfer performance is excellent, temperature runaway is avoided, and the mass transfer and heat transfer efficiency of the reaction can be significantly improved;

[0030] 3. The present invention adopts a microchannel reactor to carry out the reaction to prepare 2,2-bis(3-m-nitrobenzamide-4-hydroxyphenyl)hexafluoropropane. The reaction container is small in size and highly safe, which greatly reduces potential safety hazards in actual production.

[0031] 4. The present invention adopts a microchannel reactor to carry out the reaction, which avoids the intermediate separation step in the reaction process, simplifies the operation, shortens the reaction time, and improves the production efficiency;

[0032] 5. The synthesis process of the present invention is simpler and easier to operate. Compared with the existing synthesis route of 2,2-bis(3-m-nitrobenzamide-4-hydroxyphenyl)hexafluoropropane, it is safer, produces less waste, is more environmentally friendly, has lower production costs, and can ensure a higher yield, thus being more suitable for large-scale industrial production. DETAILED DESCRIPTION

[0033] Unless otherwise specified, all raw materials used in the following examples are commercially available products.

[0034] 6FAP 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane is a commercially available product.

[0035] Example 1

[0036] A method for preparing 2,2-bis(3-m-nitrobenzamide-4-hydroxyphenyl)hexafluoropropane by a microchannel reactor, wherein the reaction temperature of the microchannel reactor is controlled by an external heat exchanger, the heat exchange medium is heat transfer oil, and the diameter of the microchannel reactor is 0.5 mm.

[0037] The method steps are as follows:

[0038] (1) 150 g of 6FAP (0.41 mol) and 600 g of ethylene glycol butyl ether were mixed and stirred to form a 6FAP solution; m-nitrobenzoyl chloride was melted in hot water, and after it was completely melted, 228.24 g (1.23 mol) of m-nitrobenzoyl chloride was weighed, and 456.48 g of NMP was added to dissolve the m-nitrobenzoyl chloride to obtain an acylating agent;

[0039] (2) After preheating at 25° C., a 6FAP solution and an acylating agent were pumped into a microchannel reactor at flow rates of 25 g / min and 8.6 g / min respectively through metering pumps. At this time, the molar ratio of 6FAP to m-nitrobenzoyl chloride was 1:3, the reaction temperature was controlled to be 45° C., the residence reaction time was 60 s, and the reaction product was cooled by a cooling coil to obtain a discharge liquid containing 2,2-bis(3-m-nitrobenzamide-4-hydroxyphenyl)hexafluoropropane;

[0040] (3) The discharge liquid is slowly poured into 900 g of methanol aqueous solution (methanol 450 g, pure water 450 g), and the mixture is filtered and separated using a Buchner funnel. Deionized formamide is added to the product obtained after filtration to remove metal ions. The mass of deionized formamide is 5 times the mass of 6FAP. Finally, the crude product is washed with pure water in small amounts and multiple times. After being dried at 80° C., refined 2,2-bis(3-m-nitrobenzamide-4-hydroxyphenyl)hexafluoropropane is obtained. The mother liquor is decompressed to recover methanol and then recycled through a microchannel reactor. The reaction yield is 95.3% and the purity is 98.5%.

[0041] Example 2

[0042] A method for preparing 2,2-bis(3-m-nitrobenzamide-4-hydroxyphenyl)hexafluoropropane by a microchannel reactor, wherein the reaction temperature of the microchannel reactor is controlled by an external heat exchanger, the heat exchange medium is heat transfer oil, and the diameter of the microchannel reactor is 3 mm. The method steps are as follows:

[0043] (1) 150 g of 6FAP (0.41 mol) and 750 g of ethylene glycol butyl ether were mixed and stirred to form a 6FAP solution; m-nitrobenzoyl chloride was melted in hot water, and after it was completely melted, 267.21 g (1.44 mol) of m-nitrobenzoyl chloride was weighed, and 531.96 g of NMP was added to dissolve the m-nitrobenzoyl chloride to obtain an acylating agent;

[0044] (2) After preheating at 25° C., the 6FAP solution and the acylating agent were pumped into the microchannel reactor at flow rates of 25 g / min and 8.6 g / min respectively through metering pumps. At this time, the molar ratio of 6FAP to m-nitrobenzoyl chloride was 1:3.5, the reaction temperature was controlled to be 45° C., the residence time was 60 s, and the reaction product was cooled by a cooling coil to obtain a discharge liquid containing 2,2-bis(3-m-nitrobenzamide-4-hydroxyphenyl)hexafluoropropane;

[0045] (3) The discharge liquid is slowly poured into 900 g of methanol aqueous solution (methanol 450 g, pure water 450 g), and the mixture is filtered and separated using a Buchner funnel. Deionized formamide is added to the product obtained after filtration to remove metal ions. The mass of deionized formamide is 5 times the mass of 6FAP. Finally, the crude product is washed with pure water in small amounts and multiple times. After being dried at 80° C., refined 2,2-bis(3-m-nitrobenzamide-4-hydroxyphenyl)hexafluoropropane is obtained. The mother liquor is decompressed to recover methanol and then recycled through a microchannel reactor. The reaction yield is 96.8% and the purity is 98.4%.

[0046] Example 3

[0047] A method for preparing 2,2-bis(3-m-nitrobenzamide-4-hydroxyphenyl)hexafluoropropane by a microchannel reactor, wherein the reaction temperature of the microchannel reactor is controlled by an external heat exchanger, the heat exchange medium is heat transfer oil, the diameter of the microchannel reactor is 5 mm, and the method steps are as follows:

[0048] (1) 150 g of 6FAP (0.41 mol) and 900 g of ethylene glycol butyl ether were mixed and stirred to form a 6FAP solution; m-nitrobenzoyl chloride was melted in hot water, and after it was completely melted, 304.32 g (1.64 mol) of m-nitrobenzoyl chloride was weighed, and 608.64 g of NMP was added to dissolve the m-nitrobenzoyl chloride to obtain an acylating agent;

[0049] (2) After preheating at 25° C., a 6FAP solution and an acylating agent were pumped into a microchannel reactor at flow rates of 25 g / min and 8.6 g / min respectively through metering pumps. At this time, the molar ratio of 6FAP to m-nitrobenzoyl chloride was 1:4, the reaction temperature was controlled to be 45° C., the residence time was 60 s, and the reaction product was cooled by a cooling coil to obtain a discharge liquid containing 2,2-bis(3-m-nitrobenzamide-4-hydroxyphenyl)hexafluoropropane;

[0050] (3) The discharge liquid is slowly poured into 900 g of methanol aqueous solution (methanol 450 g, pure water 450 g), and the mixture is filtered and separated using a Buchner funnel. Deionized formamide is added to the product obtained after filtration to remove metal ions. The mass of deionized formamide is 5 times the mass of 6FAP. Finally, the crude product is washed with pure water in small amounts and multiple times. After being dried at 80° C., refined 2,2-bis(3-m-nitrobenzamide-4-hydroxyphenyl)hexafluoropropane is obtained. The mother liquor is decompressed to recover methanol and then recycled through a microchannel reactor. The reaction yield is 96.4% and the purity is 98.1%.

[0051] Example 4

[0052] A method for preparing 2,2-bis(3-m-nitrobenzamide-4-hydroxyphenyl)hexafluoropropane by a microchannel reactor, wherein the reaction temperature of the microchannel reactor is controlled by an external heat exchanger, the heat exchange medium is heat transfer oil, and the diameter of the microchannel reactor is 3 mm.

[0053] The method steps are as follows:

[0054] (1) 150 g of 6FAP (0.41 mol) and 1050 g of ethylene glycol butyl ether were mixed and stirred to form a 6FAP solution; m-nitrobenzoyl chloride was melted in hot water, and after it was completely melted, 228.24 g (1.23 mol) of m-nitrobenzoyl chloride was weighed, and 456.48 g of NMP was added to dissolve the m-nitrobenzoyl chloride to obtain an acylating agent;

[0055] (2) After preheating at 25° C., a 6FAP solution and an acylating agent were pumped into a microchannel reactor at flow rates of 25 g / min and 8.6 g / min respectively through metering pumps. At this time, the molar ratio of 6FAP to m-nitrobenzoyl chloride was 1:3, the reaction temperature was controlled to be 45° C., the residence time was 50 s, and the reaction product was cooled by a cooling coil to obtain a discharge liquid containing 2,2-bis(3-m-nitrobenzamide-4-hydroxyphenyl)hexafluoropropane;

[0056] (3) The discharge liquid is slowly poured into 900 g of methanol aqueous solution (methanol 450 g, pure water 450 g), and the mixture is filtered and separated using a Buchner funnel. Deionized formamide is added to the product obtained after filtration to remove metal ions. The mass of deionized formamide is 5 times the mass of 6FAP. Finally, the crude product is washed with pure water in small amounts and multiple times. After being dried at 80° C., refined 2,2-bis(3-m-nitrobenzamide-4-hydroxyphenyl)hexafluoropropane is obtained. The mother liquor is decompressed to recover methanol and then recycled through a microchannel reactor. The reaction yield is 95.8% and the purity is 97.8%.

[0057] Comparative Example 1

[0058] The method for preparing 2,2-bis(3-m-nitrobenzamide-4-hydroxyphenyl)hexafluoropropane does not use a microchannel reactor, and the specific method is as follows:

[0059] In a 500ml three-necked flask, add 6FAP (75.0g, 0.2mol) and NMP (300.0g), stir to dissolve. Melt m-nitrobenzoyl chloride in hot water in advance, weigh 113.19g (0.61mol) after it is completely melted, and add 226.38g NMP to dissolve m-nitrobenzoyl chloride, then add acylating agent dropwise at 30°C, after the addition is complete, heat to 45°C, and continue to react for 12h. After the reaction is completed, slowly pour the mother liquor into 450g of methanol aqueous solution (methanol 225g + pure water 225g), filter and separate the above mixture with a Buchner funnel, and finally wash the crude product with pure water in small amounts and multiple times. After drying at 80°C, refined 2,2-bis (3-m-nitrobenzamide-4-hydroxyphenyl) hexafluoropropane is obtained. The reaction yield is 65.8% and the purity is 67.6%.

[0060] Comparative Example 2

[0061] The method described in Example 1 is different in that:

[0062] In step (1), N-methylpyrrolidone was used instead of ethylene glycol butyl ether. The other steps were carried out as in Example 1. The reaction yield of the product was 70.8% and the purity was 88.6%.

[0063] Comparative Example 3

[0064] The method described in Example 1 is different in that:

[0065] In step (1), acetone was used instead of ethylene glycol butyl ether, and the rest was carried out as in Example 1. The reaction yield of the product was 72.8% and the purity was 89.3%.

[0066] Comparative Example 4

[0067] The method described in Example 1 is different in that:

[0068] In step (1), methanol was used instead of ethylene glycol butyl ether, and the rest was carried out as in Example 1. The reaction yield of the product was 75.8% and the purity was 89.9%.

[0069] In summary, it can be seen from Comparative Examples 1-4 that the reaction yield is significantly reduced when the microchannel reactor is not used, and the yield of the product is also reduced when N-methylpyrrolidone, acetone, methanol, and ethanol are used instead of ethylene glycol butyl ether.

[0070] Experimental example

[0071] 1. The amount of ethylene glycol butyl ether in Example 1 was changed to 50g, 100g, 150g, 1800g, and 2000g respectively. The rest was carried out according to Example 1. After the reaction was completed, the reaction yield and purity were compared. The results are shown in Table 1.

[0072] Table 1

[0073] Dosage of Ethylene Glycol Butyl Ether Yield % purity% 50g 68.4 72.5 100g 73.5 72.8 150g 78.4 80.4 600g 95.3 98.5 750g 96.8 98.4 900g 96.4 98.1 1800g 94.7 97.6 2000g 94.2 97.2

[0074] It can be seen from the data in Table 1 that the amount of ethylene glycol butyl ether is too small and the yield is low. With the increase of the amount of ethylene glycol butyl ether, the yield gradually increases. However, when the amount of ethylene glycol butyl ether exceeds 750g, the yield begins to show a downward trend. The amount of ethylene glycol butyl ether is too large, which affects the product yield and produces side reactions that affect the product purity.

[0075] 2. The reaction time in Example 1 was changed, and the residence reaction time was 10s, 20s, 30s, 40s, 50s, 2min, 5min, and 10min respectively; the rest was carried out as in Example 1. After the reaction was completed, the reaction yield and purity were compared. The results are shown in Table 2.

[0076] Table 2

[0077] Reaction time Yield % purity% 10s 80.3 78.5 20s 84.2 78.8 30s 85.5 80.4 40s 88.2 80.6 50s 95.1 97.5 60s 95.3 98.5 2min 95.2 97.1 5min 95.2 96.5

[0078]

[0079] It can be seen from the data in Table 2 that if the reaction time is too short, the reaction is not complete, resulting in residual raw materials, resulting in relatively low yield and purity. If the reaction time is extended, the yield will increase. However, if the reaction time is too long, the reaction yield will decrease to a certain extent. This is because if the reaction time is too long, side reactions may occur, and the purity will also decrease.

[0080] 3. The mass ratio of methanol to pure water in Example 1 was changed to 8:2, 7:3, 6:4, 1:1, 4:6, and 3:7, respectively. The rest was carried out as in Example 1. After the reaction was completed, the reaction yield and purity were compared. The results are shown in Table 3.

[0081] Table 3

[0082] The mass ratio of methanol to pure water Yield % purity% 8:2 94.0 95.45 7:3 94.7 96.2 6:4 94.8 96 1:1 95.3 98.5 4:6 94.9 96.3 3:7 94.6 97

[0083] It can be seen from the data in Table 3 that when the mass ratio of methanol to pure water is 1:1, the yield and purity are the highest.

Claims

1. A method for preparing 2,2-bis(3-m-nitrobenzamide-4-hydroxyphenyl)hexafluoropropane using a microchannel reactor, comprising: (1) 6FAP and ethylene glycol butyl ether are fully mixed and preheated to obtain a 6FAP solution, and the 6FAP solution and the preheated acylating agent are used as two streams; (2) controlling the flow rate of the materials by a metering pump, so that the 6FAP solution and the acylating agent are respectively pumped into the microchannel reactor for mixed reaction, and the product obtained by the reaction flows out from the outlet of the reactor; (3) The material obtained from the outlet of the microchannel reactor is collected and post-processed to obtain pure 2,2-bis(3-nitrobenzamide-4-hydroxyphenyl)hexafluoropropane.

2. The method according to claim 1, characterized in that In step (1), the mass of ethylene glycol butyl ether is 4 to 10 times the mass of 6FAP. More preferably, the mass of ethylene glycol butyl ether is 4 to 7 times the mass of 6FAP.

3. The method according to claim 1, characterized in that In step (1), the acylating agent is a mixture of m-nitrobenzoyl chloride and N-methylpyrrolidone, and the mass ratio of m-nitrobenzoyl chloride to N-methylpyrrolidone is 1:

2.

4. The method according to claim 1, characterized in that In step (1), the molar ratio of 6FAP to m-nitrobenzoyl chloride is 1:3-4.

5. The method according to claim 1, characterized in that In step (1), the preheating temperature is 0 to 60°C, and more preferably, the preheating temperature is 10 to 30°C.

6. The method according to claim 1, characterized in that In step (2), the reaction temperature of the microchannel reactor is controlled by an external heat exchanger, the heat exchange medium is heat transfer oil, the reaction temperature is 10 to 70° C., and the reaction residence time is 5 to 180 s.

7. The method according to claim 1, characterized in that The microchannel reactor module is a direct-flow microchannel reactor or an enhanced mixing continuous flow microchannel reactor. The transverse cross-section of the direct-flow microchannel reactor is a ring. The enhanced mixing continuous flow microchannel reactor series module is composed of 5 Corning high-throughput microchannel reactors with heart-shaped channels connected in series. The direct-flow microchannel reactor and the enhanced mixing continuous-flow microchannel reactor are made of any one of glass, metal, alloy, ceramic, single crystal silicon, and fluorine-containing resin, and the hydraulic diameter of the channel is 0.5-5 mm.

8. The method according to claim 1, characterized in that The feed rate of 6FAP solution is 20-30 g / min, and the feed rate of acylating agent is 5-10 g / min.

9. The method according to claim 1, characterized in that: In step (3), the post-treatment is sequentially precipitation filtration, removal of metal ions, pure water purification, and drying. The precipitation filtration is adding an alcohol solvent for precipitation and then filtering. The alcohol solvent is a methanol aqueous solution. The mass of the alcohol solvent is 3 to 6 times the mass of 6FAP. The precipitation temperature is 10 to 25° C., and the mass ratio of ethanol to water in the methanol aqueous solution is 1:1 to 3.

10. The method according to claim 9, characterized in that To remove metal ions, a deionizer is added to the product obtained after filtration to remove metal ions. The deionizer is deionized formamide, and the mass of the deionized formamide is 5 to 10 times the mass of 6FAP. The product after purification by pure water to remove metal ions is added with pure water for stirring. The mass of the pure water is 1 to 4 times the mass of 6FAP. The number of times of pure water purification is 3 to 5 times. Drying is performed by air drying at 70 to 90°C.