Method for preparing porous silica gel carrier with high specific surface area by using water-soluble column [5] arene as pore-foaming agent and application of porous silica gel carrier

Abstract

The invention provides a method for preparing a porous silica gel carrier with a high specific surface area by using water-soluble column [5] arene as a pore-foaming agent and application of the porous silica gel carrier. Water-soluble column [5] arene is prepared from trimethylamine modified short-chain fully-brominated column [5] arene, and the porous silica gel carrier which is high in specific surface area, narrow in particle size and pore distribution range and stable in performance is prepared with the water-soluble column [5] arene as a pore-foaming agent and tetraethoxysilane as a silicon source template method. And a chromatographic column taking the carrier as a filler realizes high-efficiency separation of phenylalanine and tryptophan. The porous silica gel carrier prepared by taking the water-soluble column [5] arene as the pore-foaming agent has a relatively high specific surface area which reaches 504 m < 2 > / g, the separation degree of phenylalanine and tryptophan reaches 1.41, and the porous silica gel carrier has great research value in the aspect of chromatographic packing macromolecule separation or high-performance catalyst carrier application.

Description

Technical Field

[0001] The present invention belongs to the technical field of inorganic porous material preparation, and specifically relates to a method for preparing a high-specific-surface porous silica gel carrier using water-soluble pillar[5]arene as a porogen. The carrier is suitable for biomacromolecule separation filler or high-performance catalyst carrier. Background Art

[0002] Porous silica with high specific surface area is widely used in separation analysis, chemical industry, catalysis and environmental protection due to its advantageous properties such as high purity, low density, high specific surface area and multiple active silanol groups. In addition, since porous silica with high specific surface area has rich pore structure and active sites, it can improve the catalytic performance of the reaction and is widely used in heterogeneous catalytic reactions. Common methods for synthesizing porous silica with high specific surface area include sol-gel method, supercritical fluid drying method, template method and the like. Among them, the template method is used to improve silica, such as adding a new pore expander to further increase its pore diameter, porosity or specific surface area, so as to prepare porous silica materials with the pore structure, porosity or specific surface area required in many fields.

[0003] Pillar[n]arene is a new generation of supramolecular macrocyclic oligomers, which has attracted widespread attention due to its highly symmetrical rigid structure and easy functional modification. Water-soluble pillar[5]arene is a macrocyclic oligomer with a rigid framework and excellent electronic properties. The water-soluble pillar[5]arene obtained by functional modification has great research and application value in the fields of catalytic materials, adsorption materials, separation materials and sensor materials. In view of this, the present invention uses water-soluble supramolecular pillar[5]arene as a porogen to synthesize a new type of high specific surface area porous silica, which is expected to play an important role in the field of biomacromolecule separation or new catalytic carrier. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for preparing a high specific surface area porous silica gel carrier using water-soluble pillar[5]arene as a porogen and its application.

[0005] 1. Preparation of high specific surface area porous silica gel carrier (1) Synthesis of short-chain perbrominated pillar[5]arene: Dissolve bis(2-bromoethoxy)benzene, paraformaldehyde, and boron trifluoride etherate in 1,2-dichloroethane under nitrogen atmosphere at room temperature and normal pressure. Stir and react for 2-2.5 hours. After the reaction is completed, quench with methanol and purify by column chromatography to obtain short-chain perbrominated pillar[5]arene. The molar ratio of bis(2-bromoethoxy)benzene, paraformaldehyde, and boron trifluoride etherate is 1:(0.5-1.0):(0.5-1.0).

[0006] The synthetic route of short-chain fully brominated pillar[5]arenes is as follows: (2) Synthesis of water-soluble pillar[5]arene: Short-chain perbrominated pillar[5]arene was dispersed in anhydrous acetone, and an ethanolic solution of trimethylamine was added. The mixture was refluxed at 75-80°C for 10-12 hours, and then washed and distilled under reduced pressure to obtain water-soluble pillar[5]arene; the molar ratio of short-chain perbrominated pillar[5]arene to trimethylamine was 1:10-1:15.

[0007] The synthetic route is as follows: (3) Preparation of porous silica gel carrier: Water-soluble column [5] aromatic hydrocarbon is used as a porogen, mixed with ammonia water, cyclohexane, and tert-butanol, and tetraethyl orthosilicate is added as a silicon source. The mixture is stirred at 40-50°C and 300-400 rpm for 10-12 hours. After washing, drying, and calcination, a high specific surface area porous silica gel carrier is obtained; the porous silica gel is then dispersed in 50 mL of toluene, 1.0 mL of 8-(trimethoxysilyl)octylamine is added, and mechanical stirring is performed at 100°C for 12 hours before loading onto a 25 cm chromatographic column for efficient separation of amino acids. The mass ratio of water-soluble column [5] aromatic hydrocarbon and tetraethyl orthosilicate is 1:2-1:5; the volume ratio of water, cyclohexane, and tert-butanol is 1:(1-2):(0.1-0.2) 2. Structural Characterization NMR of short-chain fully brominated column[5] aromatics 1 The H NMR resonance spectrum is shown in Figure 1. The peak at 6.91 ppm is the H of the benzene ring of the short-chain fully brominated pillar[5]arene, the peak at 4.23 ppm is the H of the methylene group in the alkyl chain adjacent to the oxygen, the peak at 3.84 ppm is the H of the methylene bridged by the benzene ring, and the peak at 3.63 ppm is the H on the carbon atom of the alkyl chain adjacent to the bromine, indicating the successful synthesis of the short-chain fully brominated pillar[5]arene. 1 H NMR (400 MHz, CDCl3, rt), δ(ppm): 6.91 (s, 10H), 4.23(t, 20H), 3.84(s, 10H), 3.63 (t, 20H). 1 The H NMR resonance spectrum is shown in Figure 2. The peak at 6.84 ppm is the H of the short-chain fully brominated column [5] aromatic hydrocarbon benzene ring, the peak at 4.35~4.48 ppm is the H in the methylene group adjacent to O in the alkyl chain, the peak at 3.70~3.82 ppm is the H of the alkyl group adjacent to N and the methylene group in front, the peak at 3.22 ppm is the H of the methylene bridged by the benzene ring, and the peak at 3.11 ppm is the H of the methyl group, indicating the successful synthesis of water-soluble column [5] aromatic hydrocarbon. 1H NMR (400 MHz, D2O, rt), δ(ppm): 6.84 (s, 10H), 4.35~4.48 (d, 20H), 3.70~3.82 (d, 20H), 3.22 (s, 10H), 3.11 (s, 90H).

[0008] The infrared spectrum of water-soluble columnar[5]arene is as follows Figure 3 As shown, 2950~2920 cm -1 The strong absorption peak is the CH stretching vibration in the alkyl chain, 1574 cm -1 The C=C stretching vibration peak of the benzene ring is 1460 cm -1 The peak is the bending vibration of N-CH3, 1232 cm -1 The broad band is the CN bond stretching vibration, 806 cm -1 The peak of the polysubstituted benzene ring vibration is 731 cm -1 The peaks are the alkyl chain plane swing vibration peaks, and infrared characterization confirms the successful preparation of water-soluble pillar[5]arene.

[0009] The morphology of the high specific surface area porous silica gel carrier prepared by using water-soluble pillar[5]arene as porogen under the above optimal conditions was characterized by scanning electron microscopy ( Figure 4 ), the study found that the high specific surface area porous silica gel carrier prepared with water-soluble columnar [5] aromatic hydrocarbon as porogen showed a spherical morphology with a particle size of 3~5 μm. Further screening can obtain silica gel carriers of specific sizes suitable for chromatography or catalyst support materials.

[0010] N2 adsorption / desorption isotherms and pore size distribution of high specific surface area porous silica gel carriers Figure 5 、 Figure 6 Please provide analysis and explanation to show that the prepared material has a high specific surface area porous silica gel carrier with a mesoporous structure. The specific surface area is up to 504 m 2 / g, and has high pore size and porosity, and has good application prospects.

[0011] 3. Separation performance as chromatographic filler The high specific surface area porous silica gel carrier (5.0 g) prepared with water-soluble column [5] aromatic hydrocarbon as porogen was dispersed in 50 mL of methanol, and 300 mL of chromatographic methanol was used as displacement liquid. The column was filled into an empty tube with a length and pore size of 250 mm*4.6 mm at a pressure of 45 MPa for 30 minutes to obtain a high specific surface area porous silica gel chromatographic column. Under the mobile phase conditions of methanol: water = 80:20 volume ratio, the detection wavelength was 254 nm, and the flow rate was 1.0 mL / min to achieve good separation of phenylalanine and tryptophan ( Figure 7 ).

[0012] In summary, the present invention prepares water-soluble pillar[5]arene by modifying fully brominated pillar[5]arene with trimethylamine, and uses water-soluble pillar[5]arene as a porogen and ethyl orthosilicate as a silicon source template to prepare a porous silica gel carrier having a high specific surface area, a narrow particle size and pore distribution range, and stable performance. The present invention uses water-soluble pillar[5]arene as a porogen template and ethyl orthosilicate as a silicon source, thereby overcoming the problem of insufficient specific surface area when using traditional small molecules or long alkyl chain molecules as porogens to prepare porous microspheres with large pore diameters and specific surface areas. The porous SiO2 prepared by this method has a good morphology and a specific surface area as high as 504 m 2 / g, with narrow distribution ranges of pore size (13 nm) and particle size (3-5 µm), and large pore volume (1.68 cm 3 / g), the separation degree of phenylalanine and tryptophan reached 1.41, and it is also expected to play an important role in the application of chromatographic fillers in the separation of biomacromolecule proteins, serum and other target substances or as high-performance catalyst carriers. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 NMR of short-chain fully brominated column[5]arene 1 H NMR resonance spectroscopy; Figure 2 NMR of water-soluble column[5]arene 1 H NMR resonance spectroscopy; Figure 3 is the infrared spectrum of water-soluble column[5]arene; Figure 4 It is a scanning electron microscope of a porous silica gel carrier with high specific surface area; Figure 5 N2 adsorption / desorption isotherms for high specific surface area porous silica gel carrier; Figure 6 The pore size distribution of the porous silica gel carrier with high specific surface area; Figure 7 It is a high specific surface area porous silica gel for chromatographic separation. DETAILED DESCRIPTION

[0014] The present invention is described in detail below through specific embodiments.

[0015] Example 1 (1) Synthesis of short-chain perbrominated column [5] aromatic hydrocarbons: Dissolve bis(2-bromoethoxy)benzene (3.5 g, 10 mmol) in 100 mL of dry 1,2-dichloroethane solution under nitrogen atmosphere at room temperature and atmospheric pressure. Then add paraformaldehyde (1.8 g, 10 mmol) and boron trifluoride etherate (4.0 g, 10 mmol). Stir mechanically for 2 hours and then add 120 mL of methanol to quench. The resulting residue is dissolved in 200 mL of chloroform and the organic solvent is removed in vacuo. The solid is separated by column chromatography using petroleum ether: dichloromethane = 10:1 to obtain short-chain perbrominated column [5] aromatic hydrocarbons.

[0016] (2) Synthesis of water-soluble pillar[5]arene: Short-chain perbrominated pillar[5]arene (1.8 g, 10 mmol) was dispersed in 100 mL of anhydrous acetone, and 10 mL of an ethanol solution of trimethylamine (6 g, 0.1 mol) was added. The mixture was refluxed at 75°C for 10 h. After the reaction, the solvent was distilled off under reduced pressure. The solid was washed twice with 50 mL of acetone to obtain water-soluble pillar[5]arene. (3) Preparation of high specific surface porous silica gel carrier: 0.4 g of porogen water-soluble column [5] aromatic hydrocarbon, 20 mL of ammonia water, 30 mL of cyclohexane and 2.0 mL of tert-butanol were added to a round-bottom flask in sequence, stirred for 30 minutes, and then 1.0 mL of ethyl orthosilicate was added. Stirred at a speed of 400 rpm and a temperature of 50 ° C for 12 hours. After the reaction was completed, the solid was filtered and washed three times with 100 mL of deionized water, dried in an oven at 50 ° C for 12 hours, and then calcined in a muffle furnace at 500 ° C for 2-3 hours to obtain a white powder, which is a high specific surface porous silica gel carrier. Specific surface area 216 m 2 / g, average pore diameter 7.8 nm, pore volume 0.34 cm 3 / g.

[0017] The high-surface-area porous silica support prepared above was dispersed in 50 mL of toluene, and 1.0 mL of 8-(trimethoxysilyl)octylamine was added. The mixture was mechanically stirred at 100°C for 12 hours before loading onto a 25 cm chromatographic column. Phenylalanine and tryptophan were separated by chromatography using a mobile phase consisting of methanol and water in a volume ratio of 80:20 at a detection wavelength of 254 nm and a flow rate of 1.0 mL / min. The retention times for phenylalanine and tryptophan were 11.2 minutes and 12.8 minutes, respectively. The separation factor (SF) for phenylalanine and tryptophan was 1.14, and the resolution reached 1.23.

[0018] Example 2 Steps (1) and (2) are the same as in Example 1; (3) Preparation of high specific surface area porous silica gel carrier: 0.4 g of porogen water-soluble column [5] aromatic hydrocarbon, 20 mL of ammonia water, 30 mL of cyclohexane and 2.0 mL of tert-butanol were added to a round-bottom flask in sequence, stirred for 30 minutes, and then 2.0 mL of ethyl orthosilicate was added. Stirring was carried out at a speed of 400 rpm and a temperature of 50 °C for 12 hours. After the reaction was completed, the solid was filtered and washed three times with 100 mL of deionized water, dried in an oven at 50 °C for 12 hours, and then calcined in a muffle furnace at 500 °C for 2-3 hours to obtain a white powder, which is a high specific surface area porous silica gel carrier. Specific surface area 303 m 2 / g, average pore diameter 8.1 nm, pore volume 0.59 cm 3 / g.

[0019] The high-surface-area porous silica support prepared above was dispersed in 50 mL of toluene, and 1.0 mL of 8-(trimethoxysilyl)octylamine was added. The mixture was mechanically stirred at 100°C for 12 hours before loading onto a 25 cm chromatographic column. Phenylalanine was detected with a retention time of 10.5 minutes and tryptophan at 12.2 minutes. The separation factor between phenylalanine and tryptophan was 1.16, and the resolution reached 1.36.

[0020] Example 3 Steps (1) and (2) are the same as in Example 1; 0.8 g of porogen water-soluble column [5] aromatic hydrocarbon, 20 mL of ammonia water, 30 mL of cyclohexane and 2.0 mL of tert-butanol were added to a round-bottom flask in sequence, stirred for 30 minutes, and then 2.0 mL of ethyl orthosilicate was added. Stirring was carried out at a speed of 400 rpm and a temperature of 50 ° C for 12 hours. After the reaction was completed, the solid was filtered and washed three times with 100 mL of deionized water, dried in an oven at 50 ° C for 12 hours, and then calcined in a muffle furnace at 500 ° C for 2 to 3 hours to obtain a white powder, which is a high specific surface area porous silica gel carrier. The specific surface area is 504 m 2 / g, average pore diameter 13.0 nm, pore volume 1.68 cm 3 / g.

[0021] The high-surface-area porous silica support prepared above was dispersed in 50 mL of toluene, and 1.0 mL of 8-(trimethoxysilyl)octylamine was added. The mixture was mechanically stirred at 100°C for 12 hours before loading onto a 25 cm chromatographic column. Phenylalanine was detected with a retention time of 10.2 minutes and tryptophan at 11.8 minutes. The separation factor between phenylalanine and tryptophan was 1.15, and the resolution reached 1.41.

Claims

1. A method for preparing a high specific surface area porous silica gel carrier using water-soluble pillar [5] aromatic hydrocarbon as a porogen, characterized in that: The following steps are involved: (1) Synthesis of short-chain fully brominated column[5]arene: Dissolve bis(2-bromoethoxy)benzene, paraformaldehyde, and boron trifluoride etherate in 1,2-dichloroethane under nitrogen atmosphere at room temperature and normal pressure. Stir and react for 2 to 2.5 hours. After the reaction is completed, quench with methanol and purify by column chromatography to obtain short-chain fully brominated column[5]arene. (2) Synthesis of water-soluble pillar[5]arene: Disperse the short-chain fully brominated pillar[5]arene in anhydrous acetone, add trimethylamine ethanol solution, reflux at 75-80°C for 10-12 hours, and distill under reduced pressure and then wash to obtain water-soluble pillar[5]arene; (3) Preparation of porous silica gel carrier: Water-soluble columnar [5] aromatic hydrocarbon is used as a porogen, mixed with ammonia water, cyclohexane and tert-butanol, and ethyl orthosilicate is added as a silicon source. The mixture is stirred at 40-50 °C and 300-400 rpm for 10-15 hours. After washing, drying and calcination, a high specific surface area porous silica gel carrier is obtained.

2. The preparation method according to claim 1, wherein: In step (1), the molar ratio of bis(2-bromoethoxy)benzene, paraformaldehyde, and boron trifluoride etherate is 1:(0.5-1.0):(0.5-1.0).

3. The preparation method according to claim 1, wherein: In step (2), the molar ratio of the short-chain fully brominated column [5] aromatic hydrocarbon to trimethylamine is 1:10 to 1:

15.

4. The preparation method according to claim 1, wherein: In step (3), the mass ratio of the water-soluble column [5] aromatic hydrocarbon to ethyl orthosilicate is 1:2 to 1:

5.

5. The preparation method according to claim 1, wherein: In step (3), the volume ratio of water, cyclohexane and tert-butanol is 1: (1-2): (0.1-0.2).

6. The preparation method according to claim 1, wherein: In step (3), drying is carried out at 50-55°C for 10-15 hours; and calcination is carried out at 400-500°C for 2-3 hours.

7. Use of a porous silica gel carrier with a high specific surface area prepared by the method according to any one of claims 1 to 6 in the separation of phenylalanine and tryptophan.

8. The use according to claim 7, characterized in that: Separation conditions for phenylalanine and tryptophan: The mobile phase was a volume ratio of methanol to water = 80:20, the detection wavelength was 254 nm, and the flow rate was 1.0 mL / min.

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