A method for synthesizing 2,3,6-triphenylpyridine compounds

Abstract

The application belongs to the technical field of organic synthesis, and discloses a method for synthesizing 2,3,6-triphenylpyridine compounds. The Pd / ETS-10 catalyst is prepared first, and then benzyl acetylene compounds and benzylamine compounds are used as substrates to realize the oxidative coupling-cycloaddition reaction of terminal acetylene and benzylamine under the action of the Pd / ETS-10 catalyst in an oxygen atmosphere, so as to synthesize the triphenylpyridine compounds by one-pot method. The synthesis method has high atom economy, the catalyst can be recycled for multiple times, and has good stability and high economic value.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthesis and develops a simple catalytic system for synthesizing triphenylpyridine compounds. Specifically, the invention uses phenylacetylene compounds and benzylamine compounds as substrates and synthesizes the triphenylpyridine compounds in one pot under the action of Pd / ETS-10. Background Art

[0002] Pyridine derivatives are a class of heterocyclic compounds with important biological activities and application potential. They are important building blocks of various alkaloids, drugs, agrochemicals, natural products, optoelectronic materials, and electrochemical materials. 2,3,6-Triphenylpyridine is one of the most common pyridine derivatives and is traditionally synthesized by the cycloaddition reaction of alkynes with benzylamines. However, the low availability, high price, and poor reactivity of diyne compounds have greatly limited the widespread application of this process. To overcome these limitations, scientific researchers have invested a lot of research to develop alternative synthetic methods to prepare 2,3,6-triphenylpyridine using inexpensive and readily available raw materials.

[0003] Titanosilicate ETS-10 is a widely used solid base catalyst. The octahedrally coordinated titanium species generate two negative charges, providing electron-donating properties. This electron-donating nature of the Lewis base adsorbs and activates electron-deficient substrates. Furthermore, the introduced ionic metal can coordinate with the framework oxygen atoms of the zeolite, resulting in changes in the metal's electronic and geometric configuration.

[0004] In the present invention, under reaction conditions without the need for additional additives, in an oxygen atmosphere, phenylacetylene and benzylamine are used as raw materials, and an oxidative coupling-cycloaddition reaction of phenylacetylene and benzylamine is carried out on an ETS-10 zeolite-supported Pd catalyst to prepare 2,3,6-triphenylpyridine. Summary of the Invention

[0005] This invention provides a one-step oxidative coupling cyclization reaction to produce 2,3,6-triphenylpyridine using phenylacetylene and benzylamine as raw materials in a simple heterogeneous catalyst system. Using ETS-10 zeolite as a support, metallic Pd is introduced into the zeolite support to prepare the Pd / ETS-10 catalyst. This catalyst achieves the oxidative coupling-cycloaddition reaction of terminal alkynes with benzylamine in an oxygen atmosphere. The invention features high economic value, multiple catalyst recycling, and a one-pot synthesis method with high atom economy.

[0006] In order to achieve the above object, the technical solution of the present invention is:

[0007] Phenylacetylene compounds and benzylamine compounds are used as reaction substrates. A certain amount of Pd / molecular sieve catalyst is added to the system. The target product is reacted within a certain period of time under an oxygen atmosphere and a specific temperature. The reaction liquid is then centrifuged and rotary evaporated, and 2,3,6-triphenylpyridine compounds are separated by column chromatography.

[0008] Reaction equation:

[0009]

[0010] R1 and R2 are independently hydrogen, alkyl or halogen.

[0011] Furthermore, R1 is selected from hydrogen, 4-methyl, and 3-methyl, and R2 is selected from hydrogen, 4-methyl, 4-fluoro, and 4-chloro.

[0012] The reaction temperature of the present invention is 80 to 160°C, more preferably 120 to 140°C.

[0013] The reaction time of the present invention is 6 to 12 hours.

[0014] The reaction solvent of the present invention can be either N,N-dimethylformamide or dimethyl sulfoxide, with dimethyl sulfoxide being preferred.

[0015] The molar ratio of the phenylacetylene compound to the benzylamine compound of the present invention is 1:5-16, preferably 1:8-11.

[0016] The dosage relationship of the Pd / molecular sieve catalyst and the phenylacetylene compound is: 10-40 mg: 0.1-0.3 mmol.

[0017] The molecular sieve of the present invention is one of mesoporous ETS-10, mesoporous ZSM-5 and mesoporous Silicalite-1; mesoporous ETS-10 is more preferred.

[0018] The Pd / ETS-10 catalyst is synthesized by the isovolumetric impregnation method. The source of the ETS-10 zeolite support is not limited, and the metal salt can be palladium nitrate, palladium acetate, or palladium chloride. The Pd loading is 0.5-1.5 wt.%, preferably 1 wt.%. The Lewis basic sites of ETS-10 and the incorporated metal together form the catalytically active center, which may contribute to the unique catalytic activity and selectivity of the oxidative coupling-cycloaddition reaction of phenylacetylene with benzylamine.

[0019] Further preferred: a catalyst is prepared from mesoporous ETS-10 and palladium nitrate, wherein the specific surface area of ​​the mesoporous ETS-10 is 250-270 m 2 / g, and the mesopore volume is 0.10~0.20cm 3 / g, with an external surface area of ​​64 to 110 m2 / g, micropore volume is 0.11~0.16cm 3 / g.

[0020] Preferably, a mesoporous ETS-10 zeolite is prepared by adding water glass and NaOH solution to a container to obtain solution A. KF solution is added to another container, followed by the slow dropwise addition of TiCl₃ solution to obtain solution B. Solution B is slowly added dropwise to solution A. The system is stirred for 30-60 minutes, and then a 7# template is added dropwise to obtain a gel. The gel is placed in a polytetrafluoroethylene-lined reactor and crystallized at 180-220°C under static conditions for 48-80 hours. After crystallization, the gel is washed with water, filtered, dried, and calcined at 450-500°C to obtain the mesoporous ETS-10 zeolite. The molar ratio of the raw materials in the gel is: 1.0 TiO₂: 6.5-8.5 SiO₂: 4.5-5.0 Na₂O: 2.5-3.5 KF: 190-230 H₂O. The 7# template is a polymer quaternary ammonium salt purchased from Hangzhou Yinhu Chemical Co., Ltd. The volume ratio of 7# template and water glass is 1:2~7.

[0021] Advantages of the present invention:

[0022] (1) The present invention realizes the oxidative coupling-cycloaddition reaction of phenylacetylene and benzylamine on a Pd catalyst supported on ETS-10 zeolite in an oxygen atmosphere under reaction conditions without the need for additional additives, using inexpensive phenylacetylene compounds and benzylamine compounds as raw materials to prepare 2,3,6-triphenylpyridine. The reaction conditions are simple, the atom economy is high, and only inexpensive substrates are required to efficiently synthesize the target product.

[0023] (2) Zeolite catalysts are non-toxic and harmless, easy to separate and recycle, and can be reused many times. They have good stability and high economic value. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is the 2,3,6-triphenylpyridine in Example 1 1 H-NMR spectrum.

[0025] Figure 2 This is the HRMS (EI) spectrum of 2-(4-methylphenyl)-3,6-diphenylpyridine in Example 5.

[0026] Figure 3 This is the HRMS (EI) spectrum of 2-(4-fluorophenyl)-3,6-diphenylpyridine in Example 6.

[0027] Figure 4 This is the HRMS (EI) spectrum of 2-(4-chlorophenyl)-3,6-diphenylpyridine in Example 7.

[0028] Figure 5 This is the HRMS (EI) spectrum of 2-phenyl-3,6-di(4-methylphenyl)-pyridine in Example 8.

[0029] Figure 6 This is the HRMS (EI) spectrum of 2-(4-methylphenyl)-3,6-di(4-methylphenyl)-pyridine in Example 9.

[0030] Figure 7 This is the HRMS (EI) spectrum of 2-(4-fluorophenyl)-3,6-di(4-methylphenyl)-pyridine in Example 10. DETAILED DESCRIPTION

[0031] The specific embodiments of the present invention are described below, but are not limited to the following examples. Reaction conditions should be changed according to actual conditions. Unless otherwise specified, the reagents and instruments used in the following examples are commercially available products.

[0032] Specific preparation method of zeolite used in the scheme:

[0033] 3.2g of NaOH was added to 16mL of distilled water to prepare a NaOH solution, to which 20.7mL of water glass was then added to obtain Solution A. 4.51g of KF·2H2O was added to 27.6mL of distilled water to prepare a KF solution. Once a clear solution was obtained, 14.08g of TiCl3 solution was added dropwise to obtain Solution B. After stirring for 30 minutes, Solution B was added dropwise to Solution A. After stirring for 60 minutes, 10mL of 20wt.% 7# template was added dropwise and stirred for another 90 minutes. The resulting gel was placed in a Teflon-lined reactor and crystallized at 190°C under static conditions for 72 hours. The gel was then washed with water, filtered, dried, and calcined at 450°C for 4 hours to obtain the mesoporous zeolite ETS-10. The molar ratio of the reaction gel system was 1.0TiO2:7.7SiO2:4.9Na2O:3.1KF:222H2O.

[0034] Pd / ETS-10: Weigh 0.0250g of palladium nitrate in an appropriate amount of distilled water to prepare an equal volume of palladium nitrate metal salt solution. This solution was added dropwise to 1.0000g of mesoporous ETS-10 zeolite by an impregnation method. The solution was allowed to stand overnight at room temperature and then oven-dried at 100°C for 10 hours to obtain a mesoporous 1% Pd / ETS-10 zeolite catalyst. This catalyst was used in the following examples.

[0035] Example 1:

[0036]

[0037] 30 mg of 1% Pd / ETS-10 zeolite, 0.3 mmol of phenylacetylene, 3 mmol of benzylamine, and 1 mL of dimethyl sulfoxide were added to a 10 mL Schlenk reaction tube. The mixture was reacted in an oxygen atmosphere at 140° C. in a heating block for 7 h. The mixture was then cooled and filtered. The conversion and selectivity were analyzed by liquid chromatography (LC). The final yield of triphenylpyridine was calculated to be 99%. The product was then separated and purified by thin layer chromatography, specifically using petroleum ether and ethyl acetate as eluents and eluted and separated by silica gel column chromatography to obtain the product. The characterization data of the product are as follows:

[0038] 1 H-NMR (400MHz, CDCl3) δ8.16–8.14(m,2H),7.78–7.77(m,2H),7.51–7.42(m,5H),7.30–7.21(m,9H)

[0039] When the palladium loading mass in the Pd / ETS-10 zeolite of Example 1 was increased to 2%, the conversion rate and selectivity were measured using LC, and no target product, triphenylpyridine, was obtained.

[0040] When the palladium loading mass in the Pd / ETS-10 zeolite of Example 1 was increased to 3%, the conversion rate and selectivity were measured using LC, and no target product, triphenylpyridine, was obtained.

[0041] Example 2:

[0042] A 10 mL Schlenk reaction tube was used as a container for the reaction system. 30 mg of 1% Pd / ETS-10 zeolite, 0.3 mmol of phenylacetylene, 3 mmol of benzylamine, and 1 mL of N,N-dimethylformamide were added to the reaction tube. The reaction was carried out in a 140 ° C heater under an oxygen atmosphere for 7 h. After cooling to room temperature, the reaction liquid was filtered and the conversion and selectivity of the reaction were analyzed by liquid chromatography (LC). The final calculated yield of triphenylpyridine was 48%. The remaining organic mixture was separated by column chromatography or thin layer chromatography, specifically using a mixture of petroleum ether (PE) and ethyl acetate (EA) as an eluent (developing agent) and eluted and separated by silica gel column chromatography to obtain the product.

[0043] Example 3:

[0044] When the reaction temperature in Example 1 was changed to 120° C. and other conditions remained unchanged, the conversion rate and selectivity were measured by LC, and the yield of triphenylpyridine was 93%.

[0045] When the reaction temperature in Example 1 was changed to 110° C. and other conditions remained unchanged, the conversion rate and selectivity were measured using LC, and the yield of triphenylpyridine was 52%.

[0046] If the reaction temperature in Example 1 is changed to 100° C. and other conditions remain unchanged, the conversion rate and selectivity are measured by LC, and the yield of triphenylpyridine is 44%.

[0047] Example 4:

[0048] 30 mg of 1% Pd / ETS-10 zeolite, 0.3 mmol of phenylacetylene, 3 mmol of benzylamine, and 1 mL of DMSO (dimethyl sulfoxide) were added to a 10 mL Schlenk reaction tube. The mixture was reacted in a 140 ° C heater in an oxygen atmosphere for 3 h, then cooled and filtered. The conversion rate and selectivity were analyzed by liquid chromatography (LC). The final calculated yield of triphenylpyridine was 88%. The product was then separated and purified by thin layer chromatography. Specifically, petroleum ether and ethyl acetate were used as eluents and silica gel column chromatography was used for elution and separation to obtain the product.

[0049] If the reaction time in Example 4 was changed to 5 h, with other conditions unchanged, and the conversion rate and selectivity were determined by LC, the yield of triphenylpyridine was 97%.

[0050] Example 5:

[0051]

[0052] In a 10 mL Schlenk reaction tube, 30 mg of 1% Pd / ETS-10 zeolite, 0.3 mmol of phenylacetylene, 3 mmol of 4-methylbenzylamine, and 1 mL of DMSO (dimethyl sulfoxide) were added. The reaction was carried out in an oxygen atmosphere at 140 ° C in a heater for 7 hours, followed by cooling and filtration. The conversion rate and selectivity were analyzed by liquid chromatography (LC). The final calculated yield of 2-(4-methylphenyl)-3,6-diphenylpyridine was 97%. The product was then separated and purified by thin layer chromatography, specifically using petroleum ether and ethyl acetate as eluents and eluted and separated by silica gel column chromatography to obtain the product. The characterization data of the product are as follows:

[0053] m / z:321.15(100.0%),322.16(26.2%),323.16(3.3%)

[0054] Example 6:

[0055]

[0056] 30 mg of 1% Pd / METS-10 zeolite, 0.3 mmol of phenylacetylene, 3 mmol of 4-fluorobenzylamine, and 1 mL of DMSO (dimethyl sulfoxide) were added to a 10 mL Schlenk reaction tube. The reaction was carried out in an oxygen atmosphere at 140 ° C in a heater for 7 hours. The temperature was then lowered and filtered. The conversion rate and selectivity were analyzed by liquid chromatography (LC). The final calculated yield of 2-(4-fluorophenyl)-3,6-diphenylpyridine was 74%. The product was then separated and purified by thin layer chromatography. Specifically, petroleum ether and ethyl acetate were used as eluents and silica gel column chromatography was used for elution and separation to obtain the product. The characterization data of the product are as follows:

[0057] m / z:325.13(100.0%),326.13(25.1%),327.13(3.1%)

[0058] Example 7:

[0059]

[0060] In a 10 mL Schlenk reaction tube, 30 mg of 1% Pd / METS-10 zeolite, 0.3 mmol of phenylacetylene, 3 mmol of 4-chlorobenzylamine, and 1 mL of DMSO (dimethyl sulfoxide) were added. The reaction was carried out in an oxygen atmosphere at 140 ° C in a heater for 7 hours, followed by cooling and filtration. The conversion rate and selectivity were analyzed by liquid chromatography (LC). The final calculated yield of 2-(4-chlorophenyl)-3,6-diphenylpyridine was 62%. The product was then separated and purified by thin layer chromatography, specifically using petroleum ether and ethyl acetate as eluents and eluted and separated by silica gel column chromatography to obtain the product. The characterization data of the product are as follows:

[0061] m / z: 341.10 (100.0%), 343.09 (32.0%), 342.10 (25.1%), 344.10 (8.0%), 343.10 (3.1%), 345.10 (1.0%)

[0062] Example 8:

[0063]

[0064] In a 10 mL Schlenk reaction tube, 30 mg of 1% Pd / ETS-10 zeolite, 0.3 mmol of 4-methylphenylacetylene, 3 mmol of benzylamine, and 1 mL of DMSO (dimethyl sulfoxide) were added. The reaction was carried out in an oxygen atmosphere at 140 ° C. in a heater for 7 hours, followed by cooling and filtration. The conversion rate and selectivity were analyzed by liquid chromatography (LC). The final calculated yield of 2-phenyl-3,6-di(4-methylphenyl)-pyridine was 90%. The product was then separated and purified by thin layer chromatography, specifically using petroleum ether and ethyl acetate as eluents and eluted and separated by silica gel column chromatography to obtain the product. The characterization data of the product are as follows:

[0065] m / z:335.17(100.0%),336.17(27.3%),337.17(3.6%)

[0066] Example 9:

[0067]

[0068] 30 mg of 1% Pd / ETS-10 zeolite, 0.3 mmol of 4-methylphenylacetylene, 3 mmol of 4-methylbenzylamine, and 1 mL of DMSO (dimethyl sulfoxide) were added to a 10 mL Schlenk reaction tube. The reaction was carried out in an oxygen atmosphere at 140 ° C. in a heater for 7 hours. The temperature was then lowered and filtered. The conversion rate and selectivity were analyzed by liquid chromatography (LC). The final calculated yield of 2-(4-methylphenyl)-3,6-di(4-methylphenyl)-pyridine was 95%. The product was then separated and purified by thin layer chromatography. Specifically, petroleum ether and ethyl acetate were used as eluents and silica gel column chromatography was used for elution and separation to obtain the product. The characterization data of the product are as follows:

[0069] m / z:349.18(100.0%),350.19(28.4%),351.19(3.9%)

[0070] Example 10:

[0071]

[0072] 30 mg of 1% Pd / ETS-10 zeolite, 0.3 mmol of 4-methylphenylacetylene, 3 mmol of 4-fluorobenzylamine, and 1 mL of DMSO (dimethyl sulfoxide) were added to a 10 mL Schlenk reaction tube. The reaction was carried out in an oxygen atmosphere at 140 ° C. in a heater for 7 hours. The temperature was then lowered and filtered. The conversion rate and selectivity were analyzed by liquid chromatography (LC). The final calculated yield of 2-(4-fluorophenyl)-3,6-di(4-methylphenyl)-pyridine was 76%. The product was then separated and purified by thin layer chromatography. Specifically, petroleum ether and ethyl acetate were used as eluents and silica gel column chromatography was used for elution and separation to obtain the product. The characterization data of the product are as follows:

[0073] m / z:353.16(100.0%),354.16(27.6%),355.16(3.6%)

[0074] Example 12:

[0075] Compared with Example 1, Example 12 differs in that ETS-10 is replaced by Silicalite-1.

[0076] The preparation method of Pd / Silicalite-1 catalyst is the same as that of Pd / ETS-10. Silicalite-1 was prepared according to the method described in "Journal of Industrial and Engineering Chemistry, 95, 2021, 376–387".

[0077] 30 mg of 1% Pd / Silicalite-1 zeolite, 0.3 mmol of phenylacetylene, 3 mmol of benzylamine, and 1 mL of DMSO (dimethyl sulfoxide) were added to a reaction tube and reacted in a 140° C. heater in an oxygen atmosphere for 7 h. The reaction was then cooled and filtered. The conversion rate and selectivity were analyzed by liquid chromatography (LC). The final calculated yield of triphenylpyridine was 43%. The product was then separated and purified by thin layer chromatography, specifically using petroleum ether and ethyl acetate as eluents and eluted and separated by silica gel column chromatography to obtain the product.

[0078] Example 13:

[0079] Example 13 differs from Example 1 in that ETS-10 is replaced with ZSM-5. The preparation method for Pd / ZSM-5 zeolite is the same as that for Pd / ETS-10. ZSM-5 was prepared according to the previously published "Journal of Catal. 330, 2015, 423–433."

[0080] 30 mg of 1% Pd / ZSM-5 zeolite, 0.3 mmol of phenylacetylene, 3 mmol of benzylamine, and 1 mL of DMSO (dimethyl sulfoxide) were added to a reaction tube and reacted in a 140° C. heater in an oxygen atmosphere for 7 h. The reaction was then cooled and filtered. The conversion rate and selectivity were analyzed by liquid chromatography (LC). The final calculated yield of triphenylpyridine was 65%. The product was then separated and purified by thin layer chromatography, specifically using petroleum ether and ethyl acetate as eluents and eluted and separated by silica gel column chromatography to obtain the product.

[0081] Comparative Example 1:

[0082] 30 mg of palladium nitrate, 0.3 mmol of phenylacetylene, 3 mmol of benzylamine, and 1 mL of DMSO (dimethyl sulfoxide) were added to the reaction tube. The reaction was carried out in a 140°C heater in an oxygen atmosphere for 7 h. The reaction was then cooled and filtered. The conversion rate and selectivity were analyzed by liquid chromatography (LC), and no target product was found.

[0083] Comparative Example 2:

[0084] Comparative Example 2 was compared to Example 1, except that Pd / ETS-10 was replaced with ETS-10. 30 mg of ETS-10, 0.3 mmol of phenylacetylene, 3 mmol of benzylamine, and 1 mL of DMSO (dimethyl sulfoxide) were added to a reaction tube. The mixture was reacted in an oxygen atmosphere at 140°C in a heating block for 7 hours. The mixture was then cooled and filtered. Liquid chromatography (LC) analysis of conversion and selectivity revealed no formation of the desired product. Comparative Example 3:

[0085] 1% Pd / C, 0.3 mmol of phenylacetylene, 3 mmol of benzylamine, and 1 mL of DMSO (dimethyl sulfoxide) were added to the reaction tube. The reaction was carried out in a 140°C heater in an oxygen atmosphere for 7 hours. The temperature was then lowered and filtered. The conversion rate and selectivity were analyzed by liquid chromatography (LC), and 20% of the target product was found to be generated.

[0086] Comparative Example 4:

[0087] Comparative Example 4 is compared with Example 1, except that the preparation method of Pd / ETS-10 is different: 0.0250 g of palladium nitrate is weighed in an appropriate amount of distilled water to prepare a palladium nitrate metal salt solution, which is added dropwise to 1.0000 g of ETS-10 zeolite by an equal volume impregnation method, and the solution is allowed to stand at room temperature overnight, then dried at 100 ° C for 10 h, and then calcined at 450 ° C to obtain Pd / ETS-10.

[0088] 30 mg of calcined Pd / ETS-10, 0.3 mmol of phenylacetylene, 3 mmol of benzylamine, and 1 mL of DMSO (dimethyl sulfoxide) were added to the reaction tube and reacted in a 140°C heater in an oxygen atmosphere for 7 hours. The mixture was then cooled and filtered. The conversion rate and selectivity were analyzed by liquid chromatography (LC), and it was found that only 15% of the target product was produced.

[0089] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for synthesizing 2,3,6-triphenylpyridine compounds, characterized in that: The phenylacetylene compound represented by Formula 1 and the benzylamine compound represented by Formula 2 are added to a solvent, a Pd / molecular sieve catalyst is added thereto, and the mixture is reacted under an oxygen atmosphere and heating conditions. After the reaction, the reaction liquid is separated and purified to obtain the 2,3,6-triphenylpyridine compound represented by Formula 3; wherein the loading amount of metal Pd on the molecular sieve is 1-1.5 wt.%; ； Wherein R1 and R2 are independently hydrogen, alkyl, or halogen; the molecular sieve is one of mesoporous ETS-10, ZSM-5, and Silicalite-1; The preparation method of Pd / molecular sieve catalyst is as follows: weigh an appropriate amount of palladium nitrate in distilled water to prepare a palladium nitrate metal salt solution of equal volume, add it dropwise to the molecular sieve zeolite by impregnation method, let it stand at room temperature, and then put it into 100 ° C drying to obtain Pd / molecular sieve catalyst.

2. The method for synthesizing 2,3,6-triphenylpyridine compounds according to claim 1, wherein: The reaction temperature is 80~160 ℃; the reaction time is 6~24 h.

3. The method for synthesizing 2,3,6-triphenylpyridine compounds according to claim 1, characterized in that: The solvent is one of N,N-dimethylformamide and dimethyl sulfoxide or a mixture of the two.

4. The method for synthesizing 2,3,6-triphenylpyridine compounds according to claim 1, characterized in that: The molar ratio of the phenylacetylene compound to the benzylamine compound is 1:5-16.

5. The method for synthesizing 2,3,6-triphenylpyridine compounds according to claim 1, characterized in that: The molecular sieve is mesoporous ETS-10; the specific surface area of ​​the mesoporous ETS-10 structure is 250~270 m 2 / g, and the mesopore volume is 0.10~0.20 cm 3 / g, with an external surface area of ​​64~110 m 2 / g, and the micropore volume is 0.11~0.16 cm 3 / g.

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