Photosensitive super-crosslinked polymer and preparation thereof, and application of photosensitive super-crosslinked polymer in synthesis of 5-hydroxyfuran-2 (5H)-ketone through photo-oxidation of furfural

Abstract

The invention belongs to the technical field of biomass catalytic conversion technology and biomass energy chemical industry, and discloses a photosensitive super-crosslinked polymer, preparation of the photosensitive super-crosslinked polymer and application of the photosensitive super-crosslinked polymer in synthesis of 5-hydroxyfuran-2 (5H)-ketone through furfural photooxidation. The preparation method comprises the following steps: mixing a monomer, a cross-linking agent and a Lewis acid catalyst in a polar aprotic solvent, and then carrying out heating reflux reaction; and after the reaction is finished, separating, washing and drying the product. The monomer is one or more of naphthalene, anthracene, phenanthrene and pyrene; the cross-linking agent is one or more of glyoxal, glyoxal dimethyl acetal, 2, 2-diethoxyethanol and bromo-acetaldehyde dimethyl acetal, and the cross-linking agent is one or more of glyoxal, glyoxal dimethyl acetal, 2, 2-diethoxyethanol and bromo-acetaldehyde dimethyl acetal. The novel photosensitive super-crosslinked polymer obtained by the invention can solve the technical problems of low photooxidation reaction conversion rate, low selectivity and complex photocatalyst synthesis process in the prior art, and especially can be used for efficient catalytic conversion of furfural to obtain HFO.

Description

Technical Field

[0001] The present invention belongs to the technical fields of biomass catalytic conversion technology and biomass energy chemical engineering technology. More specifically, it relates to a photosensitive hypercrosslinked polymer, its preparation, and its application in the photooxidation synthesis of 5-hydroxyfuran-2(5H)-one from furfural. Background Art

[0002] With the rapid consumption of global fossil energy and the increasingly serious environmental pollution problems, it is particularly important to develop technologies for the efficient utilization of renewable energy. As a renewable resource, biomass has significant advantages such as rich reserves, green cleanliness, and sustainable utilization, and is an important way to solve the energy crisis and environmental pollution. Converting biomass and its derivatives into high-value-added chemicals through green chemical methods has important scientific value and social significance in the current energy transformation and environmental protection fields.

[0003] Furfural (2-furaldehyde) is a typical bio-based platform compound. Due to its unique furan ring and formyl group structure, it has high chemical reactivity and is an important biomass derivative with low cost and easy availability. Furfural can be further derived into a variety of high-value-added chemicals through a series of chemical conversion reactions, showing broad application prospects.

[0004] 5-Hydroxyfuran-2(5H)-one [also known as 4-hydroxybutenoic acid lactone, English name: 5-hydroxyfuran-2(5H)-one (HFO)] is an oxygen-containing five-membered heterocyclic compound. HFO can be obtained by the oxidation of furfural. Its structure contains both an electron-deficient double bond, an ester group, and an acetal fragment of an α,β-unsaturated carbonyl compound, and theoretically has multiple reactivities and the potential to be a bio-based platform compound.

[0005] The reported methods for synthesizing HFO mainly fall into two categories: one is the H2O2 oxidation method, and the other is the photo-oxidation method. The H2O2 oxidation method is a thermochemical method. Fukuoka et al. (see details in: Atsushi Fukuoka, Abhijit Shrotri, ACS Catal., 2024, 14(4), 2545-2551.) used molecular sieve TS-1 as a catalyst to directly oxidize furfural with 30% hydrogen peroxide to obtain HFO, but found that the catalytic efficiency of TS-1 was very low, with a feed ratio of TS-1 to furfural greater than 1:2 and a feed ratio of hydrogen peroxide to furfural exceeding 19:1. Considering the relatively high cost of hydrogen peroxide, it is a more ideal choice to use the photo-oxidation method with oxygen as the oxidant to prepare HFO. However, the current traditional photo-oxidation method uses dyes as photocatalysts (or called photosensitizers) to initiate the oxidation reaction to synthesize HFO (for example, see: L. Doeer and R. E. Willette, J. Org. Chem., 1973, 38, 3878.). The traditional HFO synthesis system selects organic small molecule photosensitizers such as methylene blue (for example, see: Ben L. Feringa, et al, Angew. Chem. Int. Ed. 2022, 61, e202112618.), rose bengal, etc. as photosensitizers, and relatively ideal yields can be obtained. These small molecule photosensitizers have the advantages of being cheap and easily available, and having a relatively high singlet oxygen activation efficiency, but they cannot be recycled in the reaction system, accompanied by problems such as complex post-treatment and high environmental costs, so their industrial utilization is very difficult. In addition to small molecule photosensitizers, the prior art (for example, see: DeRosa, M. C.; Crutchley, R. J., Coord. Chem. Rev., 2002, 233-234, 351-371.) has reported that semiconductor materials can also generate singlet oxygen under light irradiation. However, the currently developed semiconductor photocatalysts still face problems such as cumbersome preparation processes and low selectivity for synthesizing the target product HFO (the HFO yield is only 22%) (for example, see: F. Wang, et al, Chem. Asian J. 2023, 18, e202300732.). Summary of the Invention

[0006] In view of the above-mentioned defects or improvement requirements of the prior art, the object of the present invention is to provide a photosensitive hypercrosslinked polymer, its preparation method and its application in the photooxidation synthesis of 5-hydroxyfuran-2(5H)-one from furfural. A novel photosensitive hypercrosslinked polymer is prepared, which can solve the technical problems of low conversion rate, low selectivity in the photooxidation reaction and complex synthesis process of the photocatalyst in the prior art. In particular, it can be used for the efficient catalytic conversion of furfural to obtain HFO. The preparation process of the photosensitive hypercrosslinked polymer in the present invention is simple and low-cost, and exhibits excellent photocatalytic performance, significantly improving the conversion rate and selectivity of the photooxidation synthesis of HFO from furfural, providing an important technical support for the efficient conversion of biomass resources.

[0007] To achieve the above object, according to one aspect of the present invention, a preparation method of a photosensitive hypercrosslinked polymer is provided, which is characterized in that a monomer, a crosslinking agent and a Lewis acid catalyst are mixed in a polar aprotic solvent, and then heated under reflux for reaction; after the reaction is completed, the product is separated, washed and dried to obtain the photosensitive hypercrosslinked polymer;

[0008] Among them, the monomer is one or more of naphthalene, anthracene, phenanthrene, pyrene;

[0009] The crosslinking agent is one or more of glyoxal, glyoxal dimethyl acetal, 2,2-diethoxyethanol, bromoacetaldehyde dimethyl acetal.

[0010] As a further preference of the present invention, the polar aprotic solvent is one or more of 1,2-dichloroethane, dichloromethane, dibromomethane;

[0011] The Lewis acid catalyst is one or more of ferric chloride, ferric bromide, aluminum chloride, copper chloride, zinc bromide.

[0012] As a further preference of the present invention, the molar ratio of the monomer, the crosslinking agent and the Lewis acid catalyst is 1:(1-5):(1-3).

[0013] As a further preference of the present invention, the heating under reflux reaction is carried out at a temperature of 60-120 °C and under stirring conditions.

[0014] As a further preference of the present invention, separating the product is specifically by filtration;

[0015] The washing is specifically by washing with hydrochloric acid and absolute ethanol respectively;

[0016] The drying is specifically vacuum drying.

[0017] According to another aspect of the present invention, the present invention provides a photosensitive hypercrosslinked polymer prepared by the above-mentioned preparation method of the photosensitive hypercrosslinked polymer.

[0018] According to another aspect of the present invention, the present invention provides the use of the above-mentioned photosensitive hypercrosslinked polymer in the photooxidation synthesis of 5-hydroxyfuran-2(5H)-one from furfural.

[0019] As a further preference of the present invention, the above use specifically includes the following steps:

[0020] (1) Add furfural into a reaction solvent;

[0021] (2) Add the photosensitive hypercrosslinked polymer into the reaction system, continuously introduce oxygen, and carry out a stirring reaction under light irradiation conditions;

[0022] (3) After the reaction is completed, distill the reaction solution under reduced pressure and then separate it by column chromatography to obtain the product 5-hydroxyfuran-2(5H)-one.

[0023] As a further preference of the present invention, in step (1), the reaction solvent is one or more of methanol, ethanol, isopropanol, and acetonitrile;

[0024] Preferably, the reaction solvent is methanol, acetonitrile or a mixed solvent of both; more preferably, the mixed solvent is obtained by mixing methanol and acetonitrile in a volume ratio of (0-4):(0-4);

[0025] In step (2), the wavelength of the light irradiation is 365-525 nm, and the reaction time of the stirring reaction is 6-24 hours.

[0026] As a further preference of the present invention, step (3) further includes separating the solid photosensitive hypercrosslinked polymer from the reaction system, and the separated photosensitive hypercrosslinked polymer can be repeatedly used in the photooxidation synthesis of 5-hydroxyfuran-2(5H)-one from furfural;

[0027] Preferably, the separation is specifically carried out by filtering out from the reaction system;

[0028] More preferably, in step (3), the solid photosensitive hypercrosslinked polymer is first filtered out and recovered from the reaction system by filtration, and then the filtered reaction solution is distilled under reduced pressure and separated by column chromatography to obtain the product 5-hydroxyfuran-2(5H)-one.

[0029] Through the above technical solution conceived by the present invention, compared with the prior art, the present invention prepares a photosensitive hypercrosslinked polymer by using specific monomers and crosslinking agents. This photosensitive hypercrosslinked polymer can activate oxygen into singlet oxygen under light irradiation conditions, and is especially useful for the photooxidation synthesis of HFO from furfural. The monomers used to prepare the photosensitive hypercrosslinked polymer are one or more of naphthalene, anthracene, phenanthrene, and pyrene, and the crosslinking agents are glyoxal, glyoxal dimethyl acetal, 2,2-diethoxyethanol, and bromoacetaldehyde dimethyl acetal. The monomers are cheap and easy to obtain, and both the monomers and the crosslinking agents can be purchased commercially.

[0030] The photocatalyst of the present invention uses inexpensive and readily available monomers such as naphthalene and anthracene and a novel crosslinking agent to synthesize a photosensitive hypercrosslinked polymer, which can be used for the highly selective synthesis of HFO from furfural. Many scholars did not realize that molecules such as naphthalene and anthracene have the ability to activate oxygen to singlet oxygen under light illumination, nor did they realize the use of molecules such as naphthalene and anthracene as monomers to synthesize photosensitive hypercrosslinked polymers for the selective synthesis of HFO from furfural. The commonly used crosslinking agents for traditional hypercrosslinked polymers are mainly dimethoxymethane and p-dichlorobenzyl. When using traditional dimethoxymethane and p-dichlorobenzyl as electrophilic "linking agents", the obtained hypercrosslinked microporous polymer has poor light responsiveness because the aromatic rings are connected by methylene groups and there is a lack of conjugated regions in the polymer. When glyoxal is used as the crosslinking agent, the vinylation of aryl nucleophiles can be achieved, and it is expected to be used as a vinyl "linking agent" to build vinyl bridges between some anthracene rings during the preparation of hypercrosslinked microporous polymers by the external crosslinking weaving method, so that the separated anthracene rings in the material are assembled into hyperconjugated fragments, thereby promoting the light responsiveness of the material. Therefore, the present invention uses photosensitive molecules such as naphthalene and anthracene as monomers and a novel crosslinking agent such as glyoxal to synthesize a photosensitive hypercrosslinked polymer, which provides a new route for the highly selective synthesis of HFO from furfural. Based on the present invention, taking anthracene as the monomer and glyoxal as the crosslinking agent as an example, the structure of the synthesized hypercrosslinked polymer is shown as follows:

[0031]

[0032] In the process of using the photosensitive hypercrosslinked polymer for the synthesis of HFO from furfural, the photosensitive hypercrosslinked polymers synthesized from different monomers and different crosslinking agents have different responses to light and different abilities to generate singlet oxygen. Therefore, different photosensitive hypercrosslinked polymers have different catalytic effects on the synthesis of HFO from furfural. The present invention can ensure the highly selective conversion of furfural into HFO by controlling the monomers used for preparing the photosensitive hypercrosslinked polymer to be one or more of naphthalene, anthracene, phenanthrene, and pyrene, and the crosslinking agent to be one or more of glyoxal, glyoxal dimethyl acetal, 2,2-diethoxyethanol, and bromoacetaldehyde dimethyl acetal.

[0033] The present invention provides a new method for converting furfural into HFO. By using the photosensitive hypercrosslinked polymer material in the present invention as a catalyst, a more simple, efficient, economical and feasible synthesis method for the synthesis of HFO from furfural can be achieved only under an oxygen environment and light illumination conditions. The synthesis route of HFO in the present invention is shown as follows. This method has significant advantages such as high reaction selectivity, mild synthesis conditions, and the catalyst can be reused multiple times, which can effectively reduce production costs.

[0034]

[0035] (Among them, PC represents photocatalyst, Photo Catalyst; (PC)* represents the excited-state photocatalyst; 1 O2 represents singlet oxygen)

[0036] In the present invention, the photosensitive hypercrosslinked polymer is a novel photocatalyst for efficiently preparing HFO. Applying the photosensitive hypercrosslinked polymer to the photooxidation of furfural to synthesize HFO, specifically, the following beneficial effects can be achieved:

[0037] 1. Compared with the prior art, the present invention provides a milder and feasible synthesis method for synthesizing HFO. The photocatalyst used in this reaction not only has excellent light absorption performance, but also has the characteristics of easy synthesis of materials, stable structure and recyclability.

[0038] 2. The reaction of the present invention can be carried out under room temperature conditions with light irradiation, and the reaction conditions are mild. In addition, the furfural photooxidation reaction of the present invention can be carried out in methanol, ethanol, isopropanol, and acetonitrile.

[0039] 3. The present invention applies the photosensitive hypercrosslinked polymer material to the catalytic production of HFO from furfural, solves the problems of low reaction yield, poor catalyst selectivity, and inability to reuse the catalyst in the reaction of preparing HFO from furfural, and broadens the sustainable new path for the high-value utilization of biomass resources to prepare fine chemicals.

[0040] It can be seen that compared with the traditional HFO synthesis method, applying the photosensitive hypercrosslinked polymer in the present invention to the photooxidation of furfural to synthesize 5-hydroxyfuran-2(5H)-one can bring advantages such as low energy consumption of the synthesis method, mild reaction conditions, high selectivity, easy recovery of the catalyst, recyclability for multiple times, and suitability for industrial production. Brief Description of the Drawings

[0041] Figure 1 It is the infrared spectrum of HCP-1 prepared in Example 1.

[0042] Figure 2 It is the solid-state nuclear magnetic carbon spectrum of HCP-1 prepared in Example 1.

[0043] Figure 3 It is the scanning electron microscope image of HCP-1 prepared in Example 1. Detailed Embodiments

[0044] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0045] Example 1

[0046] This example is about the preparation of the photosensitive hypercrosslinked polymer material HCP-1. The specific process is as follows: Using anthracene as the monomer, glyoxal as the crosslinking agent, and ferric chloride as the Lewis acid catalyst, the monomer, crosslinking agent, and catalyst are mixed in a molar ratio of 1:3:3. That is, anthracene (1.78 g, 10 mmol), glyoxal (1.74 g, 30 mmol), ferric chloride (4.87 g, 30 mmol), and 1,2-dichloroethane (20 mL) are added to a 100 mL round-bottom flask and mixed evenly. Then, it is refluxed under normal pressure at 80 °C for 24 hours. After the reaction, the solid product obtained by filtration and separation is stirred in 50 mL of 1 M dilute hydrochloric acid at 40 °C for 3 h, filtered, and the solid product is subjected to Soxhlet extraction with 300 mL of absolute ethanol for 12 h. Finally, it is dried in vacuo at 80 °C to obtain 1.42 g of the product, with a yield of 80%. This product is denoted as HCP-1.

[0047] The infrared spectrum of HCP-1 is as Figure 1 shown. It can be seen that there are stretching vibration peaks of the carbon-carbon double bonds of the benzene ring at 1600 - 1700 cm -1 , indicating that polymers are formed between anthracene and anthracene.

[0048] The solid-state nuclear magnetic carbon spectrum of HCP-1 is as Figure 2 shown. It can be seen that the crosslinking mode between anthracene and anthracene is connected by vinyl bonds.

[0049] The scanning electron microscope image of HCP-1 is as Figure 3 shown. It can be seen that the surface morphology of the material is a planar strip-shaped solid.

[0050] Examples 2 - 5

[0051] The preparation process steps of the photosensitive hypercrosslinked polymer materials in Examples 2 - 5 are generally the same as those in Example 1, except that the molar ratios of the amount of the monomer used, the amount of the crosslinking agent used, and the amount of the Lewis acid catalyst used are different (in each example, the amount of the monomer is the same as that used in Example 1, both being 10 mmol). As shown in the following table, other parameter conditions are the same as those in Example 1:

[0052] Example Monomer: Crosslinking agent: Lewis acid catalyst (molar ratio) Yield of HCP-1 (%) 2 1：1：1 58 3 1：3：2 65 4 1：3：3 80 5 1：5：3 81

[0053] Examples 6 - 9

[0054] The preparation process steps of the photosensitive hypercrosslinked polymer materials in Examples 6 - 9 are generally the same as those in Example 1, except that only the reflux reaction temperature for synthesizing the hypercrosslinked polymer is different. The reaction temperatures are as shown in the following table:

[0055] Example Reaction temperature Yield of HCP-1 (%) 6 60℃ 52 7 80℃ 80 8 100℃ 79 9 120℃ 78

[0056] Examples 10 - 13

[0057] The preparation process steps of the photosensitive hypercrosslinked polymer materials in Examples 10 - 13 are the same as those in Example 1, except that the monomers, crosslinking agents, catalysts, and solvents used are different (the amount of substance of the monomers, the amount of substance of the crosslinking agent, the amount of substance of the Lewis acid catalyst, and the volume of the solvent are all the same as those in Example 1), as shown in the following table:

[0058]

[0059]

[0060] Based on the fact that the present invention can synthesize various HCP-X materials (X = 1, 2, 3, 4, 5) in large quantities, quickly, and efficiently, these photosensitive hypercrosslinked polymer HCP-X materials (X = 1, 2, 3, 4, 5) prepared in Example 1 and Examples 10 - 13 can be used for the synthesis of HFO (the oxygen used in the synthesis of HFO is commercially available oxygen with a purity of not less than 99%).

[0061] Example 14

[0062] Synthesis method of HFO: Add furfural, photocatalyst material, and solvent to the reaction flask (for example, the photocatalyst can be added to the reaction solution containing furfural and solvent and mixed well), continuously introduce oxygen, and carry out photocatalytic reaction at room temperature (25°C). Specifically: Under the condition of continuously introducing oxygen, add furfural (2.0 g, 20 mmol), HCP-1 (1.0 g) as the photocatalyst, 50 mL of acetonitrile. After mixing, stir at room temperature and a light wavelength of 425 nm for 24 hours. After the reaction is completed, filter the photocatalyst (only the photocatalyst in the reaction system is in a solid state, so it can be recovered by simple filtration). After the reaction solution is separated by reduced pressure distillation column chromatography, 1.72 g of HFO is obtained (total yield 86%).

[0063] Examples 15 - 18

[0064] Synthesis method of HFO: Under the condition of continuously introducing oxygen, add furfural (2.0 g, 20 mmol), different HCP-X (1.0 g) as the photocatalyst, 50 mL of acetonitrile. After mixing, stir and react at room temperature and a light wavelength of 425 nm for 24 hours. After the reaction is completed, filter the photocatalyst, and the reaction solution is distilled under normal pressure and reduced pressure to obtain HFO. The specific results corresponding to different photocatalysts are shown in the following table:

[0065] Example HCP photocatalyst used Yield of HFO (%) 15 HCP-2 62 16 HCP-3 75 17 HCP-4 72 18 HCP-5 60

[0066] Examples 19 - 25

[0067] Examples 19 - 25 are generally similar to Example 14. Similarly, HCP - 1 prepared in Example 1 is used as the photocatalyst, but different reaction solvents are adopted, and other conditions are the same as those in Example 14 (the total volume of the reaction solvent is the same as that in Example 14, which is also 50 mL). The synthesis reaction effects are shown in the following table:

[0068] Example Solvent Yield of HFO (%) 19 50 mL methanol 72 20 50 mL ethanol 60 21 50 mL isopropanol 68 22 50 mL acetonitrile 86 23 25 mL methanol: 25 mL acetonitrile 72 24 20 mL methanol: 30 mL acetonitrile 78 25 10 mL methanol: 40 mL acetonitrile 81

[0069] It can be seen that when the photosensitive hypercrosslinked polymer obtained in the present invention is applied to the photo - oxidation synthesis of 5 - hydroxyfuran - 2(5H) - one from furfural, the reaction solvent can be methanol, or acetonitrile, ethanol, isopropanol, or a mixed solvent of methanol and acetonitrile. The volume ratio of methanol to acetonitrile can be a:b, where a is from 0 to 4 and b is from 0 to 4 (corresponding to any mixing ratio; of course, a and b cannot be both 0 at the same time). Of course, when acetonitrile is used alone as the solvent, the effect is better.

[0070] Examples 26 - 30

[0071] Examples 26 - 30 are generally similar to Example 14. However, different from directly using HCP - 1 prepared in Example 1 as the photocatalyst in Example 14, the photocatalyst used in Example 26 is HCP - 1 recovered by filtration from the reaction system of Example 14 (the solid obtained by filtration can be washed with ethanol and then dried, the same hereinafter). The photocatalyst used in Example 27 is HCP - 1 recovered by filtration from the reaction system of Example 26, and so on, so as to discuss the effect of the repeated use of the photocatalyst (other conditions are the same as those in Example 14). The synthesis reaction effects of Examples 26 - 30 are shown in the following table:

[0072] Example Number of repetitions Yield of HFO (%) 26 1 86 27 2 85 28 3 82 29 4 81 30 5 82

[0073] Examples 31 - 35

[0074] Examples 31 - 35 are generally similar to Example 14. Similarly, HCP - 1 prepared in Example 1 is used as the photocatalyst, but different light wavelengths are adopted (other conditions are the same as those in Example 14). The synthesis reaction effects are shown in the following table:

[0075] Example Light wavelength (nm) Yield of HFO (%) 31 365 50 32 395 68 33 425 86 34 450 80 35 525 55

[0076] Examples 36 - 39

[0077] Examples 36 - 39 are generally similar to Example 14. Similarly, HCP - 1 prepared in Example 1 is used as the photocatalyst, but different stirring reaction times are adopted (other conditions are the same as those in Example 14). The synthesis reaction effects are shown in the following table:

[0078] Example Reaction time (h) Yield of HFO (%) 36 6h 32 37 12h 66 38 18h 80 39 24h 86

[0079] Examples 40 - 43

[0080] The experimental procedures of Examples 40 - 43 are generally similar to those of Example 14. Similarly, HCP-1 prepared in Example 1 is used as the photocatalyst. However, the stirring reaction is not carried out at room temperature (25°C), but at 0°C, 40°C, 50°C, and 60°C respectively (other conditions are the same as those in Example 14). The yields of HFO synthesis are 33%, 52%, 42%, and 22% respectively. It can be seen that when the photosensitive hypercrosslinked polymer obtained in the present invention is applied to the reaction of photocatalytic oxidation of furfural to synthesize 5-hydroxyfuran-2(5H)-one, the reaction temperature can be any temperature within the range of 0 - 60°C. Of course, the reaction yield is optimal at room temperature (25°C).

[0081] Comparative Example 1

[0082] The experimental procedures of Comparative Example 1 are generally similar to those of Example 14. Similarly, HCP-1 prepared in Example 1 is used as the photocatalyst. However, there is no light irradiation during the reaction, that is, the reaction is carried out in a dark environment (other conditions are the same as those in Example 14), and the yield of HFO synthesis is 0.

[0083] Comparative Example 2

[0084] The experimental procedures of Comparative Example 2 are generally similar to those of Example 14, but no photocatalyst is added (other conditions are the same as those in Example 14), and the yield of HFO synthesis is 0.

[0085] Comparative Example 3

[0086] The experimental procedures of Comparative Example 3 are generally similar to those of Example 14. Similarly, HCP-1 prepared in Example 1 is used as the photocatalyst. However, instead of introducing oxygen, nitrogen is continuously introduced, that is, the stirring reaction is carried out in a nitrogen atmosphere (other conditions are the same as those in Example 14), and the yield of HFO synthesis is 0.

[0087] Comparative Example 4

[0088] The experimental procedures of Comparative Example 4 are generally similar to those of Example 14. Similarly, HCP-1 prepared in Example 1 is used as the photocatalyst. However, instead of introducing oxygen, air is continuously introduced, that is, the stirring reaction is carried out in an air atmosphere (other conditions are the same as those in Example 14), and the yield of HFO synthesis is 22%. The low yield of this reaction in an air environment indicates that the content of oxygen is very important for the synthesis of HFO.

[0089] It can be seen that when the photosensitive hypercrosslinked polymer obtained in the present invention is applied to the reaction of photooxidation of furfural to synthesize 5-hydroxyfuran-2(5H)-one, the conditions of light irradiation, continuous oxygen introduction, and reaction temperature can be optimized to complete the synthesis of HFO with higher selectivity of furfural.

[0090] It is easy for those skilled in the art to understand that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a photosensitive hypercrosslinked polymer, characterized in that, Mix the monomer, crosslinking agent, and Lewis acid catalyst in a polar aprotic solvent, and then heat under reflux; after the reaction is completed, separate, wash, and dry the product to obtain the photosensitive hypercrosslinked polymer; Among them, the monomer is one or more of naphthalene, anthracene, phenanthrene, and pyrene; The crosslinking agent is one or more of glyoxal, glyoxal dimethyl acetal, 2,2 - diethoxyethanol, and bromoacetaldehyde dimethyl acetal.

2. The preparation method of the photosensitive hypercrosslinked polymer according to claim 1, characterized in that, The polar aprotic solvent is one or more of 1,2 - dichloroethane, dichloromethane, and dibromomethane; The Lewis acid catalyst is one or more of iron(III) chloride, iron(III) bromide, aluminum chloride, copper(II) chloride, and zinc(II) bromide.

3. The preparation method of the photosensitive hypercrosslinked polymer according to claim 1, wherein, The molar ratio of the monomer, the crosslinking agent, and the Lewis acid catalyst is 1:(1 - 5):(1 - 3).

4. The preparation method of the photosensitive hypercrosslinked polymer according to claim 1, wherein, The heating under reflux reaction is carried out at a temperature of 60 - 120 °C and under stirring conditions.

5. The preparation method of the photosensitive hypercrosslinked polymer according to claim 1, characterized in that, The separation of the product is specifically carried out by filtration; The washing is specifically carried out by washing with hydrochloric acid and anhydrous ethanol respectively; The drying is specifically carried out by vacuum drying.

6. A photosensitive hypercrosslinked polymer prepared by the method for preparing a photosensitive hypercrosslinked polymer according to any one of claims 1 - 5.

7. The application of the photosensitive hypercrosslinked polymer according to claim 6 in the photo - oxidation synthesis of 5 - hydroxyfuran - 2(5H) - one from furfural.

8. The application according to claim 7, wherein The application specifically includes the following steps: (1) Add furfural to the reaction solvent; (2) Add the photosensitive hypercrosslinked polymer to the reaction system, continuously introduce oxygen, and carry out a stirring reaction under light irradiation conditions; (3) After the reaction is completed, carry out reduced - pressure distillation on the reaction solution and then separate by column chromatography to obtain the product 5 - hydroxyfuran - 2(5H) - one.

9. The application according to claim 7, wherein In step (1), the reaction solvent is one or more of methanol, ethanol, isopropanol, and acetonitrile; Preferably, the reaction solvent is methanol, acetonitrile, or a mixed solvent of the two; more preferably, the mixed solvent is obtained by mixing methanol and acetonitrile in a volume ratio of (0 - 4):(0 - 4); In step (2), the wavelength of the light irradiation is 365 - 525 nm, and the reaction time of the stirring reaction is 6 - 24 hours.

10. The application according to claim 7, characterized in that, Step (3) also includes separating the solid photosensitive hypercrosslinked polymer from the reaction system, and the separated photosensitive hypercrosslinked polymer can be repeatedly applied to the photo - oxidation synthesis of 5 - hydroxyfuran - 2(5H) - one from furfural; Preferably, the separation is specifically carried out by filtering out from the reaction system; More preferably, in step (3), first filter out and recover the solid photosensitive hypercrosslinked polymer from the reaction system by filtration, and then carry out reduced - pressure distillation on the filtered reaction solution and separate by column chromatography to obtain the product 5 - hydroxyfuran - 2(5H) - one.

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