Photochemical preparation method and application of tetraphenylhexahydrotetrazine compound

Abstract

The invention belongs to the technical field of organic compound preparation, and discloses a photochemical preparation method of a tetraphenylhexahydrotetrazine compound. The preparation method comprises the following steps: mixing an azobenzene compound, biborate, a carbon source and an organic solvent, wherein the carbon source comprises alkyl aldehyde or nitroalkane; and reacting under light irradiation, removing the organic solvent, and separating and purifying to obtain the compound. The tetraphenylhexahydrotetrazine compound with high yield can be prepared by taking an azobenzene compound as a raw material, taking aldehyde or nitroalkane as a carbon source, adding bis (borate), and carrying out illumination in the absence of a metal catalyst within the reaction time of less than 1 hour. Moreover, the preparation method disclosed by the invention shows wide functional group compatibility, so that various types of azobenzene compounds can be converted into tetraphenylhexahydrotetrazine compounds, and the application prospect is wide.

Description

Technical Field

[0001] This invention belongs to the field of organic compound preparation technology, and specifically relates to a photochemical preparation method for tetraphenylhexahydrotetraazine compounds. Background Technology

[0002] Tetraphenylhexahydrotetraazine compounds, as novel nitrogen heterocyclic compounds containing multiple tertiary amines, have broad application potential in the synthesis of various fine chemical products such as organic dyes, pigments, pesticides, pharmaceuticals, and functional materials.

[0003] In existing technologies, there are few methods for preparing tetraphenylhexahydrotetraazine compounds, and most of them suffer from technical problems such as high energy consumption, low yield, and poor method adaptability. For example, there are reports of synthesizing tetraazine products by reacting pre-synthesized hydrazine with formaldehyde / paraformaldehyde, but the yield is low, and both hydrazine and formaldehyde have certain toxicity, which greatly limits their application. Alternatively, tetraazine products can be synthesized by reacting biphenyl and formaldehyde in the presence of toxic and malodorous hydrogen sulfide, but this also faces problems such as extremely low yield, unstable reaction, and high toxicity of the reactants. Another method involves the reaction of azobenzene in methanol to produce tetraazine under the action of titanium dioxide. However, the reaction requires irradiation under a 400W high-pressure mercury lamp and in the presence of excess acetic acid and oxygen, which are too harsh conditions, resulting in low yield and cumbersome separation and purification steps, thus failing to attract much attention.

[0004] Therefore, there is an urgent need to develop a green, environmentally friendly, and efficient method for synthesizing tetraphenylhexahydrotetraazine compounds. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a photochemical preparation method for tetraphenylhexahydrotetraazine compounds. This method not only eliminates the need for metal catalysts and heating, but also allows for the preparation of tetraphenylhexahydrotetraazine compounds under ambient temperature conditions via light irradiation. Furthermore, the reaction time is short, the separation and purification process is simple, and the product yield is high.

[0006] The inventive concept of this invention is as follows: Using azobenzene compounds as raw materials, this invention adds borate esters and a carbon source (such as alkyl aldehydes or nitroalkanes). Utilizing the decarbonylation property of borate esters, a ring-closure reaction is initiated. Unlike the intramolecular deoxygenation ring-closure of indazole compounds, the reaction mechanism of this invention involves the reaction between azobenzene compounds and alkyl aldehydes or nitroalkanes to obtain nitrogen-containing heterocyclic compounds. This method can produce tetraphenylhexahydrotetraazine compounds in high yields with less than one hour of UV irradiation, without a metal catalyst. Furthermore, the method described in this invention exhibits broad functional group compatibility, allowing various types of azobenzene compounds to be converted into tetraphenylhexahydrotetraazine compounds, showing broad application prospects. Moreover, the preparation process does not require the addition of additional water to promote the reaction, and uses less organic solvent, effectively reducing the hazards associated with organic solvents and improving economic efficiency.

[0007] Furthermore, green chemistry index analysis shows that the preparation method of this invention has an atom economy of up to 49.9%, uses safe solvents and auxiliaries, uses renewable raw materials, produces no harmful derivatives, has no ecotoxicity, has a carbon efficiency of up to 44.4%, and a reaction mass efficiency of up to 45.6%, making it a green and efficient method for synthesizing tetraphenylhexahydrotetraazine.

[0008] To address the aforementioned technical problems, the first aspect of this invention provides a photochemical preparation method for tetraphenylhexahydrotetraazine compounds, comprising the following steps:

[0009] An azobenzene compound, a borate ester, a carbon source, and an organic solvent are mixed, wherein the carbon source includes an alkyl aldehyde or a nitroalkane; the reaction is carried out under light irradiation, the organic solvent is removed, and the mixture is separated and purified to obtain the tetraphenylhexahydrotetraazine compound.

[0010] In some embodiments of the present invention, the light is ultraviolet light, for example, an ultraviolet lamp with a wavelength of 400 nm can be used for irradiation.

[0011] In some embodiments of the present invention, the reaction time is less than 1 hour; preferably, the reaction time is 30-60 minutes.

[0012] In some embodiments of the present invention, the azobenzene compound has the general structural formula Ar. 1 -N=N-Ar 2 , where: Ar 1 and Ar 2 Each can be used to represent an aryl group or a substituted aryl group, respectively.

[0013] In some embodiments of the present invention, the aryl group is an aromatic ring with 6-16 carbon atoms; preferably, the aryl group is an aromatic ring with 6-10 carbon atoms; more preferably, the aryl group is a phenyl group.

[0014] In some embodiments of the present invention, the substituted aryl group has one or more substituent groups, and the plurality of substituent groups refers to two or more substituent groups. When there are multiple substituent groups, the multiple substituent groups may be the same or different.

[0015] In some embodiments of the present invention, the substituent group is selected from at least one of alkyl, halogen, carbonyl, alkoxy, cyano, phenyl, and trifluoromethyl.

[0016] In some embodiments of the present invention, the alkyl or alkoxy group has 1-15 carbon atoms; preferably, the alkyl or alkoxy group has 2-8 carbon atoms.

[0017] In some embodiments of the present invention, the structural formula of the azobenzene compound is selected from any of the following: .

[0018] In some embodiments of the present invention, the diboronate includes bis(catechol)boronate, abbreviated as B2cat2, with the following structure: .

[0019] In some embodiments of the present invention, the alkyl aldehyde includes glutaraldehyde, with the following structural formula: .

[0020] In some embodiments of the present invention, the nitroalkane includes 1,3-dinitropropane, with the following structural formula: .

[0021] In some embodiments of the present invention, the organic solvent is selected from at least one of N,N-dimethylformamide (DMF), tetrahydrofuran (THF), acetonitrile (MeCN), methanol (MeOH), and dichloromethane (DCM), preferably, the organic solvent is selected from DMF.

[0022] In some embodiments of the present invention, the molar ratio of the azobenzene compound, the diboronate, and the carbon source is 1:(1-3):(1-5).

[0023] In some embodiments of the present invention, the molar volume ratio of the azobenzene compound to the organic solvent is 0.1 mmol:(0.5-5) mL; preferably, the molar volume ratio of the azobenzene compound to the organic solvent is 0.1 mmol:(0.5-1) mL.

[0024] In some embodiments of the present invention, the mixing process is to simultaneously feed and mix the components, or to mix them in stages.

[0025] In some embodiments of the present invention, the reaction is carried out at normal temperature and pressure, under atmospheric conditions and light.

[0026] In some embodiments of the present invention, the method for removing organic solvents is rotary evaporation.

[0027] In some embodiments of the present invention, the separation and purification method is column chromatography or recrystallization; preferably, recrystallization is a method of extraction followed by recrystallization separation, which is more economical and environmentally friendly than column chromatography.

[0028] In some embodiments of the present invention, the structural formula of the tetraphenylhexahydrotetraazine compound is selected from any one of the following: .

[0029] The second aspect of the present invention provides the application of the photochemical preparation method of the above-mentioned tetraphenylhexahydrotetraazine compounds in the field of organic synthesis.

[0030] In some embodiments of the present invention, the application includes applications in the field of synthesis of organic dyes, pigments, pesticides, pharmaceuticals, or functional materials.

[0031] Compared with the prior art, the above-described technical solution of the present invention has at least the following technical effects or advantages: (1) In this invention, azobenzene compounds are used as raw materials, aldehydes or nitroalkanes are used as carbon sources, and borate esters are added. In the absence of metal catalysts, tetraphenylhexahydrotetraazine compounds can be obtained in a high yield by light irradiation in a reaction time of less than 1 hour.

[0032] (2) The preparation method of the present invention exhibits broad functional group compatibility, enabling various types of azobenzene compounds to be converted into tetraphenylhexahydrotetraazine compounds, which has broad application prospects. At the same time, no additional water is needed to promote the reaction during the preparation process, and less organic solvent is used; the separation and purification of the product can be carried out by non-column chromatography, which has economic and environmental characteristics. Attached Figure Description

[0033] Figure 1 The single-crystal structure of the product 1,2,4,5-tetraphenyl-1,2,4,5-hexahydrotetraazine prepared in Example 1 of the present invention; Figure 2 The single-crystal structure of the product 1,2,4,5-tetrakis(4-tert-butylphenyl)-1,2,4,5-hexahydrotetraazine prepared in Example 8 of the present invention; Figure 3 The single-crystal structure of the product 1,4,-bis(4-trifluoromethylphenyl)-2,5-diphenyl-1,2,4,5-hexahydrotetraazine prepared in Example 8 of this invention. Detailed Implementation

[0034] The present invention will now be described in detail with reference to embodiments to facilitate understanding of the invention by those skilled in the art. It is particularly important to note that the embodiments are merely illustrative of the invention and should not be construed as limiting the scope of protection of the invention. Non-essential improvements and adjustments made to the invention by those skilled in the art based on the above description should still fall within the scope of protection of the invention. Furthermore, all raw materials mentioned below, unless otherwise specified, are commercially available products; all process steps or preparation methods not mentioned in detail are process steps or preparation methods known to those skilled in the art.

[0035] Example 1: Preparation of 1,2,4,5-tetraphenyl-1,2,4,5-hexahydrotetraazine The reaction equations for the preparation of 1,2,4,5-tetraphenyl-1,2,4,5-hexahydrotetraazine (showing only the target product) are as follows: .

[0036] A non-column chromatography photochemical method for preparing tetraphenylhexahydrotetraazine compounds from azobenzene compounds includes the following steps: At room temperature and pressure, 0.6 mol of bis(catechol) borate (B2cat2), 2.0 mL of N,N-dimethylformamide, 0.2 mmol of azobenzene, and 1.0 mmol of glutaraldehyde were added sequentially to a 10 mL quartz test tube equipped with a stir bar. The mixture was sealed and placed under a 400 nm UV lamp with stirring for 30 minutes. After the light was removed, the reaction mixture was extracted with DCM and washed three times with sodium hydroxide solution. The combined organic phase was dried over anhydrous sodium sulfate, concentrated under reduced pressure, and recrystallized to obtain a purer product, yielding 1,2,4,5-tetraphenyl-1,2,4,5-hexahydrotetraazine in 75% yield.

[0037] The 1H NMR and 1C NMR characterization results of the product obtained in this embodiment are as follows: 1 H-NMR(CDCl3,400MHzδ(ppm)7.17-7.13(t,J=8.0Hz,8H),6.95-6.93(d,J=7.9Hz,8H),6.78-6.75(t,J=7.3Hz,4H),5.37(s,4H); 13 C-NMR (CDCl3, 101MHz) δ (ppm) 147.70, 129.18, 120.08, 114.13, 60.36. Example 2: 1,2,4,5-Tetra(2-methylphenyl)-1,2,4,5-hexahydrotetraazine The reaction equations for the preparation of 1,2,4,5-tetra(2-methylphenyl)-1,2,4,5-hexahydrotetraazine (showing only the target product) are as follows: .

[0038] A non-column chromatography photochemical method for preparing tetraphenylhexahydrotetraazine compounds from azobenzene compounds includes the following steps: At room temperature and pressure, 0.2 mol of bis(2-catechol borate) ester (B2cat2), 2.0 mL of N,N-dimethylformamide, 0.2 mmol of (E)-1,2-bis(2-methylphenyl)azo, and 1.0 mmol of glutaraldehyde were added sequentially to a 10 mL quartz test tube equipped with a stir bar. The mixture was stirred under ultraviolet light for 30 minutes, and then the light was removed. The reaction mixture was extracted with DCM and washed three times with sodium hydroxide solution. The combined organic phase was dried over anhydrous sodium sulfate, concentrated under reduced pressure, and recrystallized to obtain a purer product, yielding 1,2,4,5-tetra(2-methylphenyl)-1,2,4,5-hexahydrotetraazine in 74% yield.

[0039] The 1H NMR and 1C NMR characterization results of the product obtained in this embodiment are as follows: 1 H-NMR(CDCl3,400MHzδ(ppm)6.96-6.94(d, J =8.2Hz, 4H), 6.86-6.84(d, J =8.4Hz, 8H), 6.75-6.73(d, J =8.4Hz,4H),5.15(s,4H),2.23(s,12H); 13 C-NMR (CDCl3, 101MHz) δ (ppm) 142.60, 127.32, 116.61, 116.31, 114.91. 114.49, 55.61, 21.24. Example 3: 1,2,4,5-Tetra(4-methoxyphenyl)-1,2,4,5-hexahydrotetraazine The reaction equations for the preparation of 1,2,4,5-tetra(4-methoxyphenyl)-1,2,4,5-hexahydrotetraazine (showing only the target product) are as follows: .

[0040] A non-column chromatography photochemical method for preparing tetraphenylhexahydrotetraazine compounds from azobenzene compounds includes the following steps: At room temperature and pressure, 0.2 mol of bis(2-catechol borate) ester (B2cat2), 2.0 mL of N,N-dimethylformamide, 0.2 mmol of (E)-1,2-bis(4-methoxyphenyl)azo, and 1.0 mmol of glutaraldehyde were added sequentially to a 10 mL quartz test tube equipped with a stir bar. The mixture was stirred under ultraviolet light for 30 minutes, and then the light was removed. The reaction mixture was extracted with DCM and washed three times with sodium hydroxide solution. The combined organic phase was dried over anhydrous sodium sulfate, concentrated under reduced pressure, and recrystallized to obtain a purer product, yielding 1,2,4,5-tetra(4-methoxyphenyl)-1,2,4,5-hexahydrotetraazine in 74% yield.

[0041] The 1H NMR and 1C NMR characterization results of the product obtained in this embodiment are as follows: 1 H-NMR(CDCl3,400MHzδ(ppm)6.96-6.93(d, J =8.2Hz, 8H), 6.76-6.73(d, J =8.4Hz,8H),5.29(s,4H),2.20(s,12H); 13 C-NMR (CDCl3, 101MHz) δ (ppm) 143.20, 124.52, 122.61, 114.91. 116.46, 56.23, 22.46. Example 4: Preparation of 1,2,4,5-tetra(4-acetylphenyl)-1,2,4,5-hexahydrotetraazine The reaction equations for the preparation of 1,2,4,5-tetra(4-acetylphenyl)-1,2,4,5-hexahydrotetraazine (showing only the target product) are as follows: .

[0042] A non-column chromatography photochemical method for preparing tetraphenylhexahydrotetraazine compounds from azobenzene compounds includes the following steps: At room temperature and pressure, 0.2 mol of bis(2-catechol borate) ester (B2cat2), 2.0 mL of N,N-dimethylformamide, 0.2 mmol of (E)-1,2-bis(4-acetylphenyl)azo, and 1.0 mmol of glutaraldehyde were added sequentially to a 10 mL quartz test tube equipped with a stir bar. The mixture was then sealed and stirred under ultraviolet light for 30 minutes. After the light was removed, the reaction mixture was extracted with DCM and washed three times with sodium hydroxide solution. The combined organic phase was dried over anhydrous sodium sulfate, concentrated under reduced pressure, and recrystallized to obtain a purer product, yielding 1,2,4,5-tetra(4-acetylphenyl)-1,2,4,5-hexahydrotetraazine in 73% yield.

[0043] The 1H NMR and 1C NMR characterization results of the product obtained in this embodiment are as follows: 1 H-NMR(CDCl3,400MHzδ(ppm)6.96-6.94(d, J =8.2Hz, 8H), 6.85-6.83(d, J =8.4Hz,8H),5.29(s,4H),2.30(s,12H); 13 C-NMR (CDCl3, 101MHz) δ (ppm) 187.66, 145.37, 129.62, 128.97, 114.14, 56.62, 20.32. Example 5: 1,2,4,5-Tetra(2-chlorophenyl)-1,2,4,5-hexahydrotetraazine The reaction equations for the preparation of 1,2,4,5-tetra(2-chlorophenyl)-1,2,4,5-hexahydrotetraazine (showing only the target product) are as follows: .

[0044] A non-column chromatography photochemical method for preparing tetraphenylhexahydrotetraazine compounds from azobenzene compounds includes the following steps: At room temperature and pressure, 0.2 mol of bis(2-catechol borate) ester (B2cat2), 2.0 mL of N,N-dimethylformamide, 0.2 mmol of (E)-1,2-bis(2-chlorophenyl)azo, and 1.0 mmol of glutaraldehyde were added sequentially to a 10 mL quartz test tube equipped with a stir bar. The mixture was then sealed and stirred under ultraviolet light for 30 minutes. After the light was removed, the reaction mixture was extracted with DCM and washed three times with sodium hydroxide solution. The combined organic phase was dried over anhydrous sodium sulfate, concentrated under reduced pressure, and recrystallized to obtain a purer product, yielding 1,2,4,5-tetra(2-chlorophenyl)-1,2,4,5-hexahydrotetraazine in 68% yield.

[0045] The 1H NMR and 1C NMR characterization results of the product obtained in this embodiment are as follows: 1 H-NMR(CDCl3,400MHzδ(ppm)7.22-7.18(d, J =8.2Hz, 4H), 6.88-6.85(d, J =8.4Hz, 8H), 6.76-6.74(d, J =8.4Hz, 4H), 5.46(s, 4H); 13C-NMR (CDCl3, 101MHz) δ (ppm) 142.60, 127.32, 116.61, 116.31, 114.91. 114.49, 55.61, 21.24. Example 6: 1,2,4,5-Tetra(4-biphenyl)-1,2,4,5-Hexahydrotetraazine The reaction equations for the preparation of 1,2,4,5-tetra(4-biphenyl)-1,2,4,5-hexahydrotetraazine (showing only the target product) are as follows: .

[0046] A non-column chromatography photochemical method for preparing tetraphenylhexahydrotetraazine compounds from azobenzene compounds includes the following steps: At room temperature and pressure, 0.2 mol of bis(2-catechol)boronic acid ester (B2cat2), 2.0 mL of N,N-dimethylformamide, 0.2 mmol of (E)-1,2-tetra(4-biphenyl)azo, and 1.0 mmol of glutaraldehyde were added sequentially to a 10 mL quartz test tube equipped with a stir bar. The mixture was then sealed and placed under sunlight with stirring for 30 minutes. After the light exposure was stopped, the reaction mixture was extracted with DCM and washed three times with sodium hydroxide solution. The combined organic phase was dried over anhydrous sodium sulfate, concentrated under reduced pressure, and recrystallized to obtain a purer product, yielding 1,2,4,5-tetra(4-biphenyl)-1,2,4,5-hexahydrotetraazine in 69% yield.

[0047] The 1H NMR and 1C NMR characterization results of the product obtained in this embodiment are as follows: 1 H-NMR(CDCl3,400MHzδ(ppm)7.36-7.34(d, J =8.4Hz, 8H), 7.27-7.25(d, J =8.2Hz, 10H), 7.15-7.13(d, J =8.4Hz, 8H), 6.95-6.93(d, J =8.2Hz, 10H), 5.37(s, 4H); 13 C-NMR (CDCl3, 101MHz) δ (ppm) 142.48, 129.01, 117.33, 116.81, 115.72. 114.36, 56.04. Example 7: 1,2,4,5-Tetra(4-cyanophenyl)-1,2,4,5-hexahydrotetraazine The reaction equations for the preparation of 1,2,4,5-tetra(4-cyanophenyl)-1,2,4,5-hexahydrotetraazine (showing only the target product) are as follows: .

[0048] A non-column chromatography photochemical method for preparing tetraphenylhexahydrotetraazine compounds from azobenzene compounds includes the following steps: At room temperature and pressure, 0.2 mol of bis(2-catechol borate) ester (B2cat2), 2.0 mL of N,N-dimethylformamide, 0.2 mmol of (E)-1,2-bis(4-cyanophenyl)azo, and 1.0 mmol of glutaraldehyde were added sequentially to a 10 mL quartz test tube equipped with a stir bar. The mixture was sealed and stirred under ultraviolet light for 30 minutes. After the light was removed, the reaction mixture was extracted with DCM and washed three times with sodium hydroxide solution. The combined organic phase was dried over anhydrous sodium sulfate, concentrated under reduced pressure, and recrystallized to obtain a purer product, yielding 1,2,4,5-tetra(4-cyanophenyl)-1,2,4,5-hexahydrotetraazine in 68% yield.

[0049] The 1H NMR and 1C NMR characterization results of the product obtained in this embodiment are as follows: 1 H-NMR(CDCl3,400MHzδ(ppm)7.22-7.18(d, J =8.4Hz, 8H), 6.85-6.81(d, J =8.4Hz, 8H), 5.41(s, 4H); 13 C-NMR (CDCl3, 101MHz) δ (ppm) 142.74, 128.53, 116.91, 115.86. 57.12. Example 8: 1,2,4,5-Tetra(4-tert-butylphenyl)-1,2,4,5-Hexahydrotetraazine The reaction equations for the preparation of 1,2,4,5-tetra(4-tert-butylphenyl)-1,2,4,5-hexahydrotetraazine (showing only the target product) are as follows: .

[0050] A non-column chromatography photochemical method for preparing tetraphenylhexahydrotetraazine compounds from azobenzene compounds includes the following steps: At room temperature and pressure, 0.2 mol of bis(2-catechol borate) ester (B2cat2), 2.0 mL of N,N-dimethylformamide, 0.2 mmol of (E)-1,2-bis(4-tert-butylphenyl)azo, and 1.0 mmol of glutaraldehyde were added sequentially to a 10 mL quartz test tube equipped with a stir bar. The mixture was then sealed and stirred under ultraviolet light for 30 minutes. After the light was removed, the reaction mixture was extracted with DCM and washed three times with sodium hydroxide solution. The combined organic phase was dried over anhydrous sodium sulfate, concentrated under reduced pressure, and recrystallized to obtain a purer product, yielding 1,2,4,5-tetra(4-tert-butylphenyl)-1,2,4,5-hexahydrotetraazine in 65% yield.

[0051] The 1H NMR and 1C NMR characterization results of the product obtained in this embodiment are as follows: 1 H-NMR(CDCl3,400MHzδ(ppm)7.10-7.08(d, J =8.2Hz, 8H), 6.84-6.81(d, J =8.6Hz,8H),5.22(s,4H),1.27(s,36H); 13 C-NMR (CDCl3, 101MHz) δ (ppm) 145.75, 126.02, 125.75, 116.34, 55.93, 31.45, 29.72. Example 9: 1,4,-Bis(4-trifluoromethylphenyl)-2,5-diphenyl-1,2,4,5-hexahydrotetraazine The reaction equations for the preparation of 1,4,-bis(4-trifluoromethylphenyl)-2,5-diphenyl-1,2,4,5-hexahydrotetraazine (showing only the target product) are as follows: .

[0052] A non-column chromatography photochemical method for preparing tetraphenylhexahydrotetraazine compounds from azobenzene compounds includes the following steps: At room temperature and pressure, 0.2 mol of bis(2-catechol borate) ester (B2cat2), 2.0 mL of N,N-dimethylformamide, 0.2 mmol of (E)-1-(4-trifluoromethylphenyl)-2-phenylazo, and 1.0 mmol of glutaraldehyde were added sequentially to a 10 mL quartz test tube equipped with a stir bar. The mixture was then sealed and stirred under ultraviolet light for 30 minutes. After the light was removed, the reaction mixture was extracted with DCM and washed three times with sodium hydroxide solution. The combined organic phase was dried over anhydrous sodium sulfate, concentrated under reduced pressure, and recrystallized to obtain a purer product, yielding 1,4,-bis(4-trifluoromethylphenyl)-2,5-diphenyl-1,2,4,5-hexahydrotetraazine in 51% yield.

[0053] The 1H NMR and 1C NMR characterization results of the product obtained in Example 9 are as follows: 1 H-NMR(CDCl3,400MHzδ(ppm)7.45-7.43(d, J =8.0Hz, 3H), 7.40-7.38(d, J =8.0Hz,2H)7.21-7.17(m, J =8.8Hz, 3H), 7.04-7.02(d, J =8.0Hz, 4H), 6.97-6.92(d, J =8.6Hz, 4H), 6.87-6.84(d, J =8.4Hz, 2H), 5.46(s, 4H); 13 C-NMR (CDCl3, 101MHz) δ (ppm) 146.86, 129.36, 126.67, 120.95, 114.53, 114.18, 113.36, 113.05, 53.40. Tetraphenylhexahydrotetraazine compounds were prepared according to the methods in Examples 1-9, except that the separation and purification methods were replaced by column chromatography or other carbon sources. The yields of the products were calculated, and the results are shown in Table 1.

[0054] The separation and purification process of column chromatography is as follows: Column chromatography is used, and the developing solvent used in the separation and purification process is a mixed solution of n-hexane / ethyl acetate (volume ratio of 15:1). During the separation and purification process of column chromatography, n-hexane / ethyl acetate eluent and silica gel powder are consumed to separate the corresponding products.

[0055] Table 1:

[0056] As shown in Table 1, the tetraphenylhexahydrotetraazine compounds prepared by the method of the present invention are suitable for separation and purification by non-column chromatography. Compared with the traditional column chromatography purification method, the non-column chromatography method has lower material costs for separation and purification, avoids the use of harmful silica gel powder, and saves separation and purification time, thus having better economic and environmental benefits.

[0057] Economic cost comparison analysis, taking Implementation Example 1 as an example, shows that if the product is separated and purified by column chromatography, the time cost is approximately 2 hours, consuming about 500 mL of hexane / ethyl acetate eluent and 50-100 g of 300-400 mesh silica gel powder, with a total material cost of approximately 100 RMB (20 mmol, 5.4 g product). Furthermore, the use of silica gel powder is harmful to human health. In contrast, the non-column chromatography method of this invention requires approximately 0.5 hours for product separation and purification, uses less than 20 mL of solvent and a small amount of sodium hydroxide solution, with a total material cost of less than 10 RMB (20 mmol, 5.4 g product). Compared to column chromatography separation and purification, this invention saves more than 90% on separation and purification materials and avoids the use of harmful silica gel powder.

[0058] For those skilled in the art, several simple deductions or substitutions can be made without departing from the inventive concept, without requiring creative effort. Therefore, any simple improvements made to this invention by those skilled in the art based on the disclosure of this invention should be within the scope of protection of this invention. The above embodiments are preferred embodiments of this invention, and all processes similar to this invention and equivalent changes should fall within the scope of protection of this invention.

Claims

1. A method for the photochemical preparation of tetraphenylhexahydro- tetrazines, characterized in that, The method comprises the following steps: The azobenzene compound, the bisborate, the carbon source and the organic solvent are mixed, the carbon source comprises alkyl aldehyde or nitroalkane; the reaction is carried out under light irradiation, the organic solvent is removed, and the tetraphenylhexahydrotetrazine compound is prepared by separation and purification.

2. The photochemical preparation method of the tetraphenylhexahydro- tetrazine compound according to claim 1, characterized by, The light is ultraviolet light; and / or the reaction time is less than 1 hour.

3. The photochemical preparation method of the tetraphenylhexahydro- tetrazine compound according to claim 1, characterized by, The azobenzene compound has a structural formula selected from any one of the following: 。 4. The photochemical preparation method of the tetraphenylhexahydro- tetrazine compound according to claim 1 or 3, characterized in that, The bisborate comprises bis-o-benzosemicarbazide borate; and / or the alkyl aldehyde comprises glutaraldehyde; and / or the nitroalkane comprises 1,3 dinitropropane.

5. The photochemical preparation method of the tetraphenylhexahydro- tetrazine compound according to claim 1, characterized by, The organic solvent is selected from at least one of N,N-dimethylformamide, tetrahydrofuran, acetonitrile, methanol, dichloromethane.

6. The photochemical preparation method of the tetraphenylhexahydro- tetrazine compound according to claim 1, characterized by, The molar ratio of the azobenzene compound, the bisborate and the carbon source is 1: (1-3): (1-5); and / or the molar volume ratio of the azobenzene compound to the organic solvent is 0.1 mmol: (0.5-5) mL.

7. The photochemical preparation method of the tetraphenylhexahydro- tetrazine compound according to claim 1, characterized by, The separation and purification method is column chromatography or recrystallization.

8. The photochemical preparation method of the tetraphenylhexahydro- tetrazine compound according to claim 1, characterized by, The tetraphenylhexahydrotetrazine compound has a structural formula selected from any one of the following: 。 9. The application of the photochemical preparation method of the tetraphenylhexahydrotetrazine compound in any one of claims 1 to 8 in the field of organic synthesis.

10. Use according to claim 9, characterized in that, The application comprises application in the fields of organic dyes, pigments, pesticides, medicines or functional material synthesis.

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