Synthesis Method and Application of a Benzothiazole-Type Aggregation-Induced Emission Enhancement Fluorescent Probe

Abstract

The present invention discloses a synthesis method and application of a benzothiazole-type aggregation-induced emission enhancement fluorescent probe. The synthesis method of the benzothiazole-type aggregation-induced emission enhancement fluorescent probe comprises the following steps: uniformly mixing intermediate C, intermediate A and a first organic solvent, adding a first base under stirring, refluxing for 24-28 h under stirring conditions, cooling to room temperature, performing rotary evaporation, column chromatography separation, and rotary evaporation to obtain the benzothiazole-type aggregation-induced emission enhancement fluorescent probe. The benzothiazole-type aggregation-induced emission enhancement fluorescent probe has excellent aggregation-induced emission enhancement performance and excellent solvatochromic performance. The benzothiazole-type aggregation-induced emission enhancement fluorescent probe has an obvious fluorescence response to trace water in tetrahydrofuran, has a fast response speed, can realize self-calibration detection, has a low detection limit, and the fluorescence peak intensity thereof has a linear relationship with the trace water content, and can be used for the detection of trace water.

Description

Technical Field

[0001] The present invention belongs to the field of fluorescent probes, and specifically relates to a synthesis method and application of a benzothiazole-type aggregation-induced emission enhancement fluorescent probe. Background Art

[0002] As is well known, the presence of trace water in chemical production may lead to problems such as reduced reaction yields and reaction quenching, and may even cause serious safety accidents. Therefore, it is undoubtedly of great practical significance to detect trace water efficiently and conveniently. Traditional trace water detection methods often have disadvantages such as low sensitivity, slow response speed, and poor convenience. Therefore, scientists have tried to apply organic fluorescent probes to the detection of trace water. However, most traditional organic fluorescent probes exhibit aggregation-caused quenching (ACQ) effects in trace water, that is, the organic fluorescent probes are quenched in the aggregated state, which severely limits the application of fluorescent probes in the detection of trace water.

[0003] Completely opposite to the ACQ effect, aggregation-induced emission (AIE) molecules are a new type of fluorescent probe molecules developed in recent years. They can exhibit the performance of fluorescence "turning on" in the aggregated state, while the fluorescence intensity is significantly reduced in dilute solutions, greatly overcoming the disadvantages of traditional fluorescent molecules. With the in-depth research, scientists have successively developed aggregation-induced emission enhancement (AEE) fluorescent probes. AEE fluorescent probes can emit strong fluorescence in both dilute solutions and aggregated states, laying the possibility for the application of fluorescent probes in liquid systems. Although AEE probes have many advantages, their molecular templates are single and often can only respond to a single external stimulus. Therefore, it is urgent to develop an AEE fluorescent probe that can respond to multiple stimuli. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a benzothiazole-type aggregation-induced emission enhancement fluorescent probe.

[0005] Another purpose of the present invention is to provide a synthesis method of a benzothiazole-type aggregation-induced emission enhancement fluorescent probe. This synthesis method constructs an A'-D-π-A type molecular skeleton and designs and synthesizes a benzothiazole-type aggregation-induced emission enhancement fluorescent probe.

[0006] Another purpose of the present invention is to provide the use of a benzothiazole-type aggregation-induced emission enhancement fluorescent probe in differentiating different organic solvents based on polarity strength.

[0007] Another purpose of the present invention is to provide the application of a benzothiazole-type aggregation-induced emission enhancement fluorescent probe in detecting the trace water content in water-soluble organic solvents.

[0008] Another object of the present invention is to provide an application of a benzothiazole-type aggregation-induced emission enhancement fluorescence probe in comparing the frying time of edible oils.

[0009] The object of the present invention is achieved by the following technical solutions.

[0010] A benzothiazole-type aggregation-induced emission enhancement fluorescence probe, the structural formula of which is as follows:

[0011] 。

[0012] A synthesis method of a benzothiazole-type aggregation-induced emission enhancement fluorescence probe, comprising the following steps:

[0013] Mix the intermediate C, intermediate A and the first organic solvent evenly, add the first base under stirring, reflux for 24 - 28 h under stirring conditions, cool to room temperature of 20 - 25 °C, and perform rotary evaporation, column chromatography separation, and rotary evaporation in sequence to obtain the benzothiazole-type aggregation-induced emission enhancement fluorescence probe, wherein the structural formula of intermediate C is ; the structural formula of intermediate A is ;

[0014] By the number of moles, the ratio of intermediate C to intermediate A is (1 - 10):(1 - 5).

[0015] In the above technical solution, the first base is one or more of sodium ethoxide and piperidine. When the first base is sodium ethoxide, the ratio of the number of moles of intermediate A, the volume of the first organic solvent, and the mass of the first base is (1 - 5):50:(0.5 - 2); when the first base is piperidine, the ratio of the number of moles of intermediate A, the volume of the first organic solvent, and the volume of the first base is (1 - 5):50:(2 - 10), the unit of the number of moles is mmol, the unit of the volume is mL, and the unit of the mass is g.

[0016] In the above technical solution, the first organic solvent is one or more of DMSO, DMF, absolute ethanol, THF, toluene, and acetonitrile.

[0017] In the above technical solution, the method for synthesizing intermediate A includes: mixing 2,6-dimethyl-4-pyrone, 1,3-indanedione and acetic anhydride evenly to obtain a reaction solution, refluxing the reaction solution for 6 to 9 hours under stirring conditions, ending the reaction, adjusting the pH to neutral with an aqueous sodium hydroxide solution, and successively performing extraction, washing, rotary evaporation, drying, and column chromatography separation to obtain intermediate A. Among them, the molar ratio of 2,6-dimethyl-4-pyrone, 1,3-indanedione and the volume ratio of acetic anhydride is (1 to 5):(1 to 5):10, the unit of the molar ratio is mmol, and the unit of the volume ratio is mL.

[0018] In the above technical solution, the temperature of the drying is 60 to 90 °C, and the time of the drying is 4 to 6 h.

[0019] In the above technical solution, the method for synthesizing intermediate C includes: mixing 4-diphenylaminobenzaldehyde, 2-methylbenzothiazole, an alcohol solution and a second base evenly to obtain a mixed solution, refluxing the mixed solution for 12 to 15 h under stirring conditions, ending the reaction, and successively performing extraction, washing, rotary evaporation, drying, and column chromatography separation to obtain intermediate B; uniformly dispersing intermediate B in a second organic solvent, adding phosphorus oxychloride, and stirring at 80 to 100 °C for 12 to 15 h to obtain intermediate C.

[0020] In the above technical solution, the structural formula of intermediate B is .

[0021] In the above technical solution, the second organic solvent is one or more of DMSO, DMF, absolute ethanol, toluene and acetonitrile, and the second base is one or more of sodium hydroxide, potassium hydroxide, sodium ethoxide and piperidine.

[0022] In the above technical solution, the alcohol solution is one or more of absolute ethanol, methanol and butanol.

[0023] In the above technical solution, by molar ratio, the ratio of 4-diphenylaminobenzaldehyde, 2-methylbenzothiazole and the second base is (1 to 5):(1 to 5):(2 to 3).

[0024] In the above technical solution, by molar ratio, the ratio of intermediate B and phosphorus oxychloride is 1:(6 to 8).

[0025] In the above technical solution, the ratio of the molar ratio of 4-diphenylaminobenzaldehyde and the volume ratio of the alcohol solution is (1 to 5):10, the unit of the molar ratio is mmol, and the unit of the volume ratio is mL.

[0026] In the above technical solution, the molar fraction of intermediate B and the volume fraction of the second organic solvent are in a ratio of 1:(40 - 60), the unit of the molar fraction is mmol, and the unit of the volume fraction is mL.

[0027] Use of the above benzothiazole-based aggregation-induced emission enhancement fluorescent probe for differentiating different organic solvents based on polarity.

[0028] Application of the above benzothiazole-based aggregation-induced emission enhancement fluorescent probe for comparing the frying time of edible oils.

[0029] In the above technical solution, the edible oil includes one or more of peanut oil, soybean oil, and corn oil.

[0030] Application of the above benzothiazole-based aggregation-induced emission enhancement fluorescent probe for detecting trace water content in water-soluble organic solvents.

[0031] In the above technical solution, the water-soluble organic solvent includes one or more of tetrahydrofuran, 1,4-dioxane, and acetone.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] (1) The benzothiazole-based aggregation-induced emission enhancement fluorescent probe of the present invention has excellent aggregation-induced emission enhancement performance and excellent solvatochromic properties.

[0034] (2) The benzothiazole-based aggregation-induced emission enhancement fluorescent probe of the present invention can be used for the detection of the quality of edible oils. As the frying time increases, the viscosity of the edible oil gradually increases, and the corresponding fluorescence intensity gradually increases. Therefore, a preliminary inspection of the quality of edible oils can be achieved.

[0035] (3) The benzothiazole-based aggregation-induced emission enhancement fluorescent probe of the present invention has an obvious fluorescence response to trace water in the water-soluble organic solvent tetrahydrofuran. The response speed is fast, self-calibrated detection can be achieved, and the detection limit is low, which is 0.021%. When the trace water content is in the range of 0% - 1.20% (v / v), the fluorescence peak intensity of the benzothiazole-based aggregation-induced emission enhancement fluorescent probe shows a linear decrease as the trace water content increases, and the linear relationship is y = -2258.53994x + 5455.6281. Description of the Drawings

[0036] Figure 1 1H NMR spectrum of the benzothiazole-based aggregation-induced emission enhancement fluorescent probe synthesized in Example 1;

[0037] Figure 2 13C NMR spectrum of the benzothiazole-based aggregation-induced emission enhancement fluorescent probe synthesized in Example 1;

[0038] Figure 3 Fluorescence emission spectra of the benzothiazole-based aggregation-induced emission enhancement (AIEgen) fluorescent probe synthesized in Example 1 in dichloromethane with different volume percentages of n-hexane;

[0039] Figure 4 Fluorescence emission spectra of the benzothiazole-based AIEgen fluorescent probe synthesized in Example 1 in different organic solvents;

[0040] Figure 5 Fluorescence emission spectra of the benzothiazole-based AIEgen fluorescent probe synthesized in Example 1 in peanut oil after different frying times;

[0041] Figure 6 Fluorescence emission spectra of the benzothiazole-based AIEgen fluorescent probe synthesized in Example 1 in tetrahydrofuran with different water contents;

[0042] Figure 7 Linear relationship diagram between the fluorescence peak intensity of the benzothiazole-based AIEgen fluorescent probe and the trace water content in tetrahydrofuran with different water contents; Detailed implementation manners

[0043] The technical solutions of the present invention will be further described in detail below with reference to the accompanying drawings and examples.

[0044] Examples 1 - 5

[0045] A synthesis method of a benzothiazole-based AIEgen fluorescent probe, comprising the following steps:

[0046] Synthesis of intermediate A:

[0047]

[0048] Put 2,6-dimethyl-4-pyrone and 1,3-indandione into a three-necked flask, add acetic anhydride and mix evenly to obtain a reaction solution. Reflux the reaction solution under stirring at the reflux temperature of acetic anhydride for H1 hours, end the reaction, adjust the pH to neutral with an aqueous sodium hydroxide solution (the content of sodium hydroxide in the aqueous sodium hydroxide solution is 30 wt%), extract with dichloromethane to obtain an organic phase, wash the organic phase 3 times with a saturated NaCl aqueous solution, then perform rotary evaporation in sequence, place it in an oven at 60 °C for drying for 4 h, and perform column chromatography separation (the eluent for column chromatography is a mixture of petroleum ether and ethyl acetate, and the ratio of petroleum ether to ethyl acetate is 10:1 by volume), to obtain a yellow solid as intermediate A, wherein the ratio of the number of moles of 2,6-dimethyl-4-pyrone, the number of moles of 1,3-indandione, and the volume of acetic anhydride is G, the unit of the number of moles is mmol, and the unit of the volume is mL.

[0049] The G and H1 of intermediate A synthesized in Examples 1 to 5 are shown in Table 1.

[0050] Table 1

[0051]

[0052] Synthesis of intermediate C:

[0053]

[0054] Put 4-diphenylaminobenzaldehyde and 2-methylbenzothiazole into a three-necked flask, add an alcohol solution and a second base and mix evenly to obtain a mixed solution. The mixed solution is refluxed for H2 hours at the reflux temperature of the alcohol solution under stirring conditions, the reaction is ended, extracted with dichloromethane to obtain an organic phase, the organic phase is washed 3 times with a saturated NaCl aqueous solution, rotary evaporated, placed in an oven at 60 °C and dried for 4 h, and separated by column chromatography (the eluent for column chromatography is a mixture of petroleum ether and ethyl acetate, and the ratio of petroleum ether to ethyl acetate is 8:1 by volume) to obtain intermediate B. Intermediate B is evenly dispersed in a second organic solvent, phosphorus oxychloride is added, and stirred at T °C for H3 hours to obtain intermediate C, wherein, by mole fraction, the ratio of 4-diphenylaminobenzaldehyde, 2-methylbenzothiazole and the second base is W, and the ratio of intermediate B to phosphorus oxychloride is N; the ratio of the mole fraction of 4-diphenylaminobenzaldehyde to the volume fraction of the alcohol solution is M; the ratio of the mole fraction of intermediate B to the volume fraction of the second organic solvent is 1:50, the unit of mole fraction is mmol, and the unit of volume fraction is mL.

[0055] The W, N, M, H2, H3, T, alcohol solution, second base and second organic solvent of intermediate C synthesized in Examples 1 to 5 are shown in Table 2.

[0056] Table 2

[0057]

[0058] Synthesis of benzothiazole-based aggregation-induced emission enhanced fluorescence probe:

[0059]

[0060] Place intermediate C and intermediate A in a three-necked flask, then add the first organic solvent and mix evenly. Rapidly add the first base under stirring, and reflux for H4 hours at the reflux temperature of the first organic solvent under stirring conditions. After the reaction is completed, cool to room temperature of 20 - 25 °C, and successively carry out rotary evaporation and column chromatography separation (the eluent for column chromatography is a mixture of petroleum ether and ethyl acetate, and by volume, the ratio of petroleum ether to ethyl acetate is 8:1), then rotary evaporation to obtain the benzothiazole-based aggregation-induced emission enhanced fluorescence probe. Among them, by mole fraction, the ratio of intermediate C to intermediate A is X; the first base is sodium ethoxide or piperidine. When the first base is sodium ethoxide, the ratio of the mole fraction of intermediate A, the volume fraction of the first organic solvent, and the mass fraction of the first base (sodium ethoxide) is V; when the first base is piperidine, the ratio of the mole fraction of intermediate A, the volume fraction of the first organic solvent, and the volume fraction of the first base (piperidine) is V. The unit of mole fraction is mmol, the unit of volume fraction is mL, and the unit of mass fraction is g.

[0061] The X, V, H4, the first organic solvent, and the first base of the benzothiazole-based aggregation-induced emission enhanced fluorescence probes synthesized in Examples 1 - 5 are shown in Table 3; the hydrogen spectrum of the benzothiazole-based aggregation-induced emission enhanced fluorescence probe synthesized in Example 1 is as Figure 1 shown, and the carbon spectrum is as Figure 2 shown.

[0062] Table 3

[0063]

[0064] Example 6

[0065] Weigh a certain amount of the benzothiazole-based aggregation-induced emission enhanced fluorescence probe synthesized in Example 1 and mix it with dichloromethane to prepare a dichloromethane stock solution with a concentration of 1.0×10 -4 mol / L of the benzothiazole-based aggregation-induced emission enhanced fluorescence probe. Place the dichloromethane stock solution in an ultrasonic cleaner, and slowly add n-hexane (as a poor solvent) or not add n-hexane under ultrasonic conditions to obtain the test solution. The volume percentage content of n-hexane in the test solution is 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, and 90% respectively.

[0066] Immediately test the fluorescence emission of the mixed test solution at an excitation wavelength of 525 nm using a fluorescence spectrophotometer, as Figure 3 shown. From Figure 3It can be seen that as the content of the poor solvent increases (in the range of 0 - 50%), the rotation of single bonds in the benzothiazole-based aggregation-induced emission enhanced fluorescence probe is hindered, and the fluorescence intensity gradually increases. When the volume percentage content of the poor solvent exceeds 50%, with the further increase of the poor solvent content, amorphous nanoparticles appear in the test solution, and the fluorescence intensity decreases, but still shows fluorescence emission. In summary, the benzothiazole-based aggregation-induced emission enhanced fluorescence probe can exhibit fluorescence emission in both liquid and aggregated states. When the volume percentage of n-hexane is 50%, the fluorescence peak intensity is the strongest, indicating that the benzothiazole-based aggregation-induced emission enhanced fluorescence probe has the property of aggregation-induced emission enhancement.

[0067] Example 7

[0068] Weigh a certain amount of the benzothiazole-based aggregation-induced emission enhanced fluorescence probe synthesized in Example 1, and mix it with an organic solvent to prepare a test solution with a concentration of 1.0×10 -4 mol / L. The organic solvents are respectively one of toluene, THF, dichloromethane, and N,N-dimethylformamide.

[0069] Immediately test the fluorescence emission of the mixed test solution at an excitation wavelength of 525 nm with a fluorescence spectrophotometer and perform normalization treatment, as Figure 4 shown. It can be seen from Figure 4 that the benzothiazole-based aggregation-induced emission enhanced fluorescence probe exhibits excellent solvatochromic properties. This is because the benzothiazole-based aggregation-induced emission enhanced fluorescence probe has good electron donors (triphenylamine structure) and electron acceptors (indenone, γ-pyrone, and benzothiazole structure), the degree of charge separation of the molecule increases, and it can be better stabilized by solvation. Different solvent polarities have different stabilizing effects on the excited state and ground state of the molecule, so that the fluorescence emission position of the benzothiazole-based aggregation-induced emission enhanced fluorescence probe changes, and thus different polar organic solvents can be qualitatively detected.

[0070] Example 8

[0071] Pour 2 L of fresh peanut oil into a pot, and add fresh potato chips in batches for frying. Add 30 g of fresh potato chips each time, and fry each batch of fresh potato chips for 20 min and then take them out. The total frying time is 20 h. At the Y h of frying, take 4 mL of the peanut oil in the pot as the oil product and mix it with the dichloromethane mother liquor (1 mL) in Example 6 to obtain an oil product sample solution, where Y h = 4 h, 8 h, 12 h, 16 h, and 20 h.

[0072] Immediately test the fluorescence emission of the mixed oil product sample solution at an excitation wavelength of 525 nm with a fluorescence spectrophotometer, as Figure 5As shown. From Figure 5 It can be seen that as the frying time increases, the fluorescence intensity of the benzothiazole-based aggregation-induced emission enhanced fluorescence probe in the oil sample solution shows a significant increase. This is because as the frying time prolongs, the viscosity of the oil gradually increases, which hinders the rotation of single bonds in the benzothiazole-based aggregation-induced emission enhanced fluorescence probe, thereby leading to an increase in fluorescence intensity. This is consistent with the results of the intramolecular rotation hindrance mechanism of the AEE probe.

[0073] Example 9

[0074] Weigh a certain amount of the benzothiazole-based aggregation-induced emission enhanced fluorescence probe synthesized in Example 1 and dissolve it in tetrahydrofuran to prepare a tetrahydrofuran stock solution with a concentration of 1.0×10 -4 mol / L. Place the tetrahydrofuran stock solution in an ultrasonic cleaner and slowly add distilled water or not add distilled water (as trace water) under ultrasonic waves to prepare test solutions with different trace water contents. The trace water contents of the test solutions (unit: % (v / v)) are 0, 0.3, 0.6, 1, 1.2, 1.5, 1.8, 2, 3, 4, 5, 6, 7, 8, 9, and 10 respectively.

[0075] Immediately test the fluorescence emission of the mixed test solution at an excitation wavelength of 525 nm using a fluorescence spectrophotometer. The fluorescence emission is as Figure 6 shown. From Figure 6 It can be seen that when there is no water in the test solution, the fluorescence intensity of the test solution is the highest; as the trace water content gradually increases, due to the influence of the intramolecular charge transfer phenomenon, the fluorescence intensity of the test solution rapidly decreases. When the trace water content is 1.5% (v / v), the fluorescence intensity of the test solution has decreased to 47% of that without water. Among them, when the trace water content is in the range of 0 - 1.2% (v / v), there is a good linear relationship between the fluorescence peak intensity of the benzothiazole-based aggregation-induced emission enhanced fluorescence probe in the test solution and the trace water content, as Figure 7 shown. The linear relationship formula is y = -2258.53994x + 5455.6281, where y represents the fluorescence peak intensity and x represents the trace water content (unit: % (v / v)). According to the detection limit (LOD) formula in the literature (Highly sensitive sensing of polarity, temperature, and acid gases by a smart fluorescent molecule, Sensors&Actuators: B. Chemical 344 (2021) 130120), the extremely low detection limit of the trace water content is calculated to be 0.021%.

[0076] The test solution with a trace water content of 0.8% (v / v) was used as an unknown sample, and its fluorescence emission at an excitation wavelength of 525 nm was measured using a fluorescence spectrophotometer to obtain a fluorescence peak intensity of 3632.5. According to the above linear relationship formula, the theoretical value of the trace water content of the unknown sample was calculated to be 0.8072% (v / v), with an error of 0.9%. Therefore, the detection of trace water in the water-soluble organic solvent tetrahydrofuran can be realized using this linear formula.

[0077] The benzothiazole-based aggregation-induced emission enhancement fluorescence probes synthesized in Examples 2 to 5 above have the same technical effects as the benzothiazole-based aggregation-induced emission enhancement fluorescence probe synthesized in Example 1.

[0078] The above provides an exemplary description of the present invention. It should be noted that any simple deformation, modification, or equivalent substitution that can be made by those skilled in the art without creative labor falls within the protection scope of the present invention without departing from the core of the present invention.

Claims

1. An application of a benzothiazole-type aggregation-induced emission enhanced fluorescent probe in comparing the frying time of edible oil, characterized in that: The total cumulative frying time was 20 h. As the frying time increased, the viscosity of the oil gradually increased, which hindered the single bond rotation in the benzothiazole-type aggregation-induced emission-enhanced fluorescent probe, thereby increasing the fluorescence intensity. The structural formula of the benzothiazole-type aggregation-induced emission-enhanced fluorescent probe is as follows: 。 2. The use according to claim 1, characterized in that The synthesis method of the benzothiazole-type aggregation-induced emission enhanced fluorescent probe comprises the following steps: The intermediate C, the intermediate A and the first organic solvent are mixed uniformly, the first base is added under stirring, the mixture is refluxed for 24 to 28 hours under stirring, cooled to room temperature of 20 to 25°C, and rotary evaporation, column chromatography separation and rotary evaporation are performed in sequence to obtain a benzothiazole-type aggregation-induced emission enhanced fluorescent probe, wherein the structural formula of the intermediate C is ; The structural formula of intermediate A is ; Calculated by amount of substance, the ratio of intermediate C to intermediate A is (1~10):(1~5).

3. The use according to claim 2, characterized in that: The first base is one or more of sodium ethoxide and piperidine. When the first base is sodium ethoxide, the ratio of the amount of intermediate A, the volume of the first organic solvent and the mass of the first base is (1-5):50:(0.5-2). When the first base is piperidine, the ratio of the amount of intermediate A, the volume of the first organic solvent and the volume of the first base is (1-5):50:(2-10). The unit of the amount of substance is mmol, the unit of the volume is mL, and the unit of the mass is g.

4. The use according to claim 2, characterized in that: The first organic solvent is one or more of DMSO, DMF, anhydrous ethanol, THF, toluene and acetonitrile.

5. The use according to claim 2, characterized in that: The method for synthesizing intermediate A comprises: uniformly mixing 2,6-dimethyl-4-pyrone, 1,3-indanedione and acetic anhydride to obtain a reaction solution, refluxing the reaction solution under stirring conditions for 6 to 9 hours, terminating the reaction, adjusting the pH to neutral with a sodium hydroxide aqueous solution, sequentially performing extraction, washing, rotary evaporation, drying and column chromatography separation to obtain intermediate A, wherein the ratio of the amount of 2,6-dimethyl-4-pyrone, the amount of 1,3-indanedione and the volume of acetic anhydride is (1 to 5): (1 to 5): 10, the unit of the amount of the substance is mmol, and the unit of the volume is mL.

6. The use according to claim 2, characterized in that: The method for synthesizing intermediate C comprises: uniformly mixing 4-diphenylaminobenzaldehyde, 2-methylbenzothiazole, an alcohol solution and a second base to obtain a mixed solution, refluxing the mixed solution under stirring conditions for 12 to 15 hours, terminating the reaction, sequentially performing extraction, washing, rotary evaporation, drying, and column chromatography separation to obtain intermediate B; uniformly dispersing intermediate B in a second organic solvent, adding phosphorus oxychloride, and stirring at 80 to 100° C. for 12 to 15 hours to obtain intermediate C; The structural formula of the intermediate B is .

7. The use according to claim 6, characterized in that: The second organic solvent is one or more of DMSO, DMF, anhydrous ethanol, toluene and acetonitrile; the second base is one or more of sodium hydroxide, potassium hydroxide, sodium ethoxide and piperidine.

8. The use according to claim 6, characterized in that: The alcohol solution is one or more of anhydrous ethanol, methanol and butanol.

9. The use according to claim 6, characterized in that: Calculated by molar mass, the ratio of 4-diphenylaminobenzaldehyde, 2-methylbenzothiazole and the second base is (1-5): (1-5): (2-3); calculated by molar mass, the ratio of intermediate B and phosphorus oxychloride is 1: (6-8).

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