An ionic carbon nitride photocatalyst, a preparation method thereof and a method for photocatalytic synthesis of sulfenamide compounds

Abstract

The application discloses an ionic carbon nitride photocatalyst, a preparation method thereof and a method for photocatalytically synthesizing a sulfenamide compound. The catalyst takes carbon nitride as a base, and carbon and metal cations are doped in the carbon nitride. (1) A carbon nitride precursor, a metal chloride and 2,4,6-triaminopyrimidine are mixed and ground, dried, and subjected to first high-temperature calcination at 500-600 DEG C for 3-5 hours, and then washed, dried and obtained as an intermediate product; (2) the intermediate product and potassium thiocyanate are mixed and ground, and subjected to second high-temperature calcination at 500-520 DEG C for 0.5-1.5 hours under an inert atmosphere, and then washed, dried and obtained as the ionic carbon nitride photocatalyst. A mercapto compound, an amine compound, the ionic carbon nitride photocatalyst and acetonitrile are subjected to photoreaction in an oxygen or air environment at 0.1-0.3 MPa and at 0-40 DEG C for 5-24 hours, and a sulfenamide compound is obtained. The ionic carbon nitride photocatalyst prepared by the application has a wide range of substrates and does not need to use an alkali assistant in the process of synthesizing the sulfenamide compound.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of synthesis of hydrazine amide compounds, and particularly relates to an ionic carbon nitride photocatalyst, a preparation method thereof and a method for photocatalytic synthesis of hydrazine amide compounds. BACKGROUND

[0002] Hydrazine amide compounds containing S-N bonds are an important bioactive framework, and have a wide range of applications in organic synthesis, medicine, fine chemicals, material science and biological science. In the field of medicine, some hydrazine amide drugs have good effects in antibacterial, antiviral and antidepressant aspects. In the field of biological science, research shows that hydrazine amide compounds have excellent activity in improving endothelial function and plasma hemostasis. In the field of materials, hydrazine amide compounds including N-tert-butyl-benzothiazole-2-sulfonamide (TBBS), N-cyclohexyl benzothiazole-2-sulfonamide (CBS) and N-oxadiethyl-benzothiazole sulfonamide (NOB) have been widely used as rubber vulcanization accelerators in industry. In view of the important role of S-N bonds in medicine, biology and materials, exploring green, simple and efficient preparation methods has become a popular research field in the organic synthesis of S-N bonds.

[0003] Currently, there are many studies on the method for synthesizing sulfenamide compounds containing S-N bonds. Chinese Patent CN114540843 A reports an electrochemical synthesis method of sulfenamide compounds, using mercapto compounds and amine compounds as starting materials, using potassium iodide as an electrolyte, and mixing the obtained mixed solution of acetonitrile and water (1:1) to obtain a mixed solution as a reaction solution, and then performing a reaction under the condition of a reaction current of 10 mA for 6 h at room temperature to prepare a sulfur-containing compound with S-N bond. This method needs to add potassium iodide as an electrolyte during preparation, and has the disadvantages of harsh preparation conditions, narrow substrate range, etc. Sustainable aerobic oxidative coupling of thiols and amines for selective formation of sulfenamides using MOF-derived cobalt nanoparticles supported on N-doped carbon [J]. New Journal of Chemistry, 2022, 46(48): 23321-23327, this paper reports a new method for catalyzing the aerobic oxidative coupling of thiols and amines to generate sulfenamide compounds using cobalt nanoparticle-supported nitrogen-doped carbon materials. 2-mercaptobenzothiazole and tert-butylamine were used as raw materials, oxygen atmosphere, cobalt nanoparticle-supported nitrogen-doped carbon material as catalyst, potassium carbonate as additive, dissolved in dimethyl sulfoxide, 45 ℃ reaction for 4 h. This method has the disadvantages of requiring external alkali, non-environmental solvent, unavoidable salt-containing wastewater, and low yield of catalyst preparation.

[0004] The above methods have the problems of low catalytic efficiency, narrow adaptability, the need for additional heating or harsh reaction conditions when constructing sulfenamide compounds. The use of organic solvents makes the product post-treatment step complicated and difficult, and the inorganic / organic waste liquid increases the post-treatment cost. Therefore, these unfavorable factors greatly limit the use of the above methods.

[0005] In summary, from the perspective of the biological structure of sulfenamide compounds containing organic S-N bonds and the production of fine chemical industry, in order to solve the common problem of three wastes generated in the existing preparation process, it is very important to construct a method for green and clean preparation of sulfenamide compounds containing S-N bonds by reducing the use of alkali as an additive, realizing good substrate adaptability, and aerobic oxidative coupling. SUMMARY

[0006] In order to overcome the deficiencies in the prior art, the purpose of the present application is to provide an ionic carbon nitride photocatalyst, a preparation method thereof, and a method for photocatalytic synthesis of sulfenamide compounds

[0007] To achieve the above object, the technical scheme adopted by the present application is as follows:

[0008] An ionic carbon nitride photocatalyst, the catalyst taking carbon nitride as a base, carbon and metal cations being doped in the carbon nitride, the metal cations being K + , Na + , Ca 2+ , Fe 3+ , Co 2+ or Cu 2+ .

[0009] A preparation method of the ionic carbon nitride photocatalyst, the steps being as follows:

[0010] (1) mixing, grinding and drying carbon nitride precursors, metal chlorides and 2,4,6-triaminopyrimidine, then first high-temperature calcining at 500-600 ℃ for 3-5 h, finally washing and drying to obtain an intermediate product; wherein the metal chlorides are chlorides corresponding to the metal cations, the molar ratio of the carbon nitride precursors to the metal chlorides is 1:(2-4), the mass ratio of the carbon nitride precursors to the 2,4,6-triaminopyrimidine is (1-8):(0-8) and the 2,4,6-triaminopyrimidine cannot be 0;

[0011] (2) mixing and grinding the intermediate product prepared in step (1) and potassium thiocyanate, then second high-temperature calcining at 500-520 ℃ for 0.5-1.5 h under an inert atmosphere, finally washing and drying to obtain the ionic carbon nitride photocatalyst; wherein the mass ratio of the intermediate product to the potassium thiocyanate is 1:(2-5).

[0012] Preferably, in step (1), the carbon nitride precursors are melamine, double cyanamide or urea; the metal chlorides are potassium chloride, sodium chloride, calcium chloride, iron chloride hexahydrate, cobalt chloride hexahydrate or copper chloride.

[0013] Preferably, in step (2), the second high-temperature calcining adopts two-step heating: first heating to 380-400 ℃ for 0.5-1.5 h, then heating to 500-520 ℃ for 0.5-1.5 h.

[0014] Preferably, in step (1) and step (2), all the drying is vacuum drying, the temperature of the vacuum drying being 40-100 ℃, all the washing refers to centrifugal washing several times with a mixed solvent composed of water and anhydrous ethanol in a volume ratio of (1-4):(6-9) as a washing agent (the centrifugal washing speed being 8000-10000 rpm and the time being 5-60 min), and the inert atmosphere refers to nitrogen, argon or helium.

[0015] A method for synthesizing a sulfenamide compound by using the ionic carbon nitride photocatalyst: a mercapto compound, an amine compound, the ionic carbon nitride photocatalyst and acetonitrile are subjected to photoreaction in an oxygen or air environment at 0.1-0.3 MPa and at 0-40 DEG C for 5-24 h; after the reaction is completed, post-treatment is performed to obtain the sulfenamide compound.

[0016] Preferably, the mercapto compound is a mercaptan or a thiophenol; and the amine compound is an aliphatic amine or an aromatic amine.

[0017] Preferably, the molar ratio of the mercapto compound to the amine compound is 1:(1-24); the molar volume ratio of the mercapto compound to acetonitrile is 1 mmol:(1-4) mL; and the amount of the ionic carbon nitride photocatalyst is 0.5-12% of the mercapto compound in terms of mass ratio.

[0018] Preferably, the light is a white xenon lamp or a white LED lamp, or is one of the light sources with wavelengths of 365 nm, 455 nm, 525 nm, 600 nm and 650 nm.

[0019] Preferably, the post-treatment step is as follows: after the reaction is completed, the reaction solution is filtered, the obtained solid material after the filtration is the catalyst, and after being washed and dried, the catalyst is reused; saturated sodium chloride solution is added to the obtained solution after the filtration, and the solution is extracted several times with diethyl ether; the obtained organic layer after the extraction is washed with saturated sodium chloride solution, then with water, and then dried with anhydrous magnesium sulfate, and after the removal of magnesium sulfate by filtration, column chromatography is performed, the eluent is a mixture of petroleum ether and ethyl acetate in a volume ratio of (10-15):1, and the obtained eluent is filtered and dried to obtain the sulfenamide compound.

[0020] Advantages: (1) the ionic carbon nitride photocatalyst prepared by the method has low cost, is simple to recover, can be reused after being filtered and dried, and has superior catalytic activity; (2) the ionic carbon nitride photocatalyst prepared by the method has full-spectrum absorption; (3) the ionic carbon nitride photocatalyst prepared by the method can be used in the synthesis of a sulfenamide compound without using an alkali-based auxiliary agent, can effectively improve the reaction efficiency of the sulfenamide compound, shorten the reaction time, has a wide range of substrates, and has high product purity. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 X-ray diffraction pattern of the ionic carbon nitride prepared in Example 1.

[0022] Figure 2 Infrared spectrum of the ionic carbon nitride prepared in Example 1.

[0023] Figure 3X-ray photoelectron spectroscopy of the ion-type carbon nitride prepared in Example 1 and Comparative Example 1.

[0024] Figure 4 Transmission electron microscopy of the ion-type carbon nitride prepared in Example 1.

[0025] Figure 5 Structural schematic diagram of the ion-type carbon nitride prepared in Example 1.

[0026] Figure 6 X-ray powder diffraction of the N-tert-butyl-2-benzothiazole sulfenamide prepared in Example 2. 1 H-NMR (a) and 13 C-NMR spectrogram (b).

[0027] Figure 7 Gas chromatography (a) - mass spectrometry (b) combined spectrogram of the N-tert-butyl-2-benzothiazole sulfenamide prepared in Example 2.

[0028] Figure 8 X-ray powder diffraction of the N-thio-diethyl-2-benzothiazole sulfenamide prepared in Example 10. 1 H-NMR (a) and 13 C-NMR spectrogram (b). DETAILED DESCRIPTION

[0029] In order to make the present application clearer and more explicit, the present application is further described in detail below. It should be understood that the specific examples described herein are only used to explain the present application and are not used to limit the present application.

[0030] Preparation of the ion-type carbon nitride photocatalyst

[0031] Example 1

[0032] The preparation method of the ion-type carbon nitride photocatalyst is as follows:

[0033] (1) 4.0 g of melamine, 8.0 g of potassium chloride and 4.0 g of 2,4,6-triaminopyrimidine are mixed and ground, and then dried in a vacuum drying box at a temperature of 60 ℃ for 3 h; the mixture is placed in a muffle furnace, the calcination temperature is set to 600 ℃, and the temperature is raised to 600 ℃ at a rate of 3 ℃ min -1 -1, and then kept for 3 h; the temperature is lowered to room temperature, and then removed and added with a mixed solution of deionized water and anhydrous ethanol (volume ratio of 1:1); in a centrifuge, the solution is centrifuged at a speed of 9000 rpm for 20 min, and the operation is repeated for 3 times; and then dried in a vacuum drying box at a temperature of 60 ℃ for 12 h to obtain an intermediate product;

[0034] (2) Mix and grind 2.5 g of intermediate product with 5 g of potassium thiocyanate, place in a tube furnace, purge with argon gas for protection, set the calcination temperature to 400 ℃, and use programmed temperature rise at 30 ℃ min. -1 The temperature was increased to 400 °C at a rate of [missing value], held for 1 h, and then increased to 33 °C min [missing value]. -1 The temperature was increased to 500 °C at a certain rate and held for 30 min. The temperature was then reduced to room temperature. The sample was removed and a mixed solution of deionized water and anhydrous ethanol (volume ratio 1:1) was added. The sample was centrifuged at 9000 rpm for 20 min, and the process was repeated 3 times. The sample was then dried in a vacuum drying oven at 60 °C for 12 h to obtain an ionic carbon nitride photocatalyst.

[0035] Compare with Example 1

[0036] The difference from Example 1 is that 2,4,6-triaminopyrimidine was not added in step (1); everything else is the same as in Example 1.

[0037] Figure 1 The image shows the X-ray diffraction pattern of the ionic carbon nitride prepared in Example 1. The (100) and (002) peaks correspond to the in-plane packing and interlayer ordered packing structures of the ionic carbon nitride sample obtained in Example 1, respectively. The appearance of the (100) and (002) peaks indicates that the ionic carbon nitride sample obtained in Example 1 has a highly crystalline phase structure.

[0038] Figure 2 The infrared spectrum of ionic carbon nitride prepared in Example 1 is shown. The range is 3000–3600 cm⁻¹. -1 The peak at 2000–2200 cm⁻¹ represents the vibrational absorption peak of the -NHx / OH group. -1 The vibrational peak is attributed to the cyano group (-C≡N). - ) group, 1200~1700 cm -1 and 810 cm -1 The characteristic peaks at 920 cm⁻¹ represent the tensile vibration and out-of-plane bending vibration of the heptaazine ring, which forms the basic framework of carbon nitride. -1 990 cm -1 and 1160 cm -1 The vibrational peak at that point belongs to the imine-bonded metal K. + Asymmetric and symmetric changes. Figure 2 The results confirmed that Example 1 successfully prepared ionic carbon nitride and doped it with K. + .

[0039] Figure 3X-ray photoelectron spectrograms of the ionic carbon nitride prepared for Example 1 and Comparative Example 1. It can be seen that the ionic carbon nitride samples prepared in Example 1 and Comparative Example 1 contain N, C, O and K elements, but the C:N ratio in Example 1 is 0.91, and the C:N ratio in Comparative Example 1 is 0.62, the C element content in Example 1 is increased relative to Comparative Example 1, indicating that the addition of 2,4,6-triaminopyrimidine successfully dopes carbon atoms into the carbon nitride framework; as for the O element, the reason should be that the oxygen in the air environment during step (1) muffle calcination is introduced.

[0040] Figure 4 The transmission electron micrograph of the ionic carbon nitride prepared for Example 1. It can be seen that the ionic carbon nitride sample prepared in Example 1 has a layered structure.

[0041] Figure 5 The structural schematic diagram of the ionic carbon nitride photocatalyst prepared for Example 1, wherein the blue ball represents N atom, the black ball represents C atom, and the pink ball represents K atom.

[0042] Preparation of sulfenamide compounds

[0043] Examples 2-37

[0044] Preparation steps:

[0045] (1) 1 mmol of mercapto compound and 25 mg of ionic carbon nitride photocatalyst prepared in Example 1 were added into a pressure-resistant reaction tube, vacuumed, filled with 0.15 MPa of oxygen for three times, 10 mmol of amine compound and 4 mL of acetonitrile were added under the condition of oxygen filling, and the mixture was stirred at room temperature under white LED light for 8 h;

[0046] (2) After the reaction was completed, the reaction liquid was filtered, the obtained solid material was the catalyst, which could be reused after washing and drying; the obtained filtrate was a mixed solution containing sulfenamide compounds, 5 mL of saturated sodium chloride solution was added to the filtrate, and 10 mL of diethyl ether was extracted three times; the obtained organic layer was first washed with 10 mL of saturated sodium chloride three times, then washed with 10 mL of deionized water three times, then dried with anhydrous magnesium sulfate overnight, filtered to remove magnesium sulfate, and then column chromatography was performed on silica gel, the eluent was petroleum ether: ethyl acetate = 15:1 (volume ratio), and the product was obtained after filtration and drying, which was detected by gas chromatography to determine the yield.

[0047] Among them, the raw materials and products corresponding to Examples 2-37 are shown in Table 1.

[0048]

[0049]

[0050]

[0051] Figure 6 The gas chromatography (a) - mass spectrometry (b) combined spectrum of N-tert-butyl-2-benzothiazolesulfenamide prepared in Example 2, 1 H-NMR (a) and 13 C-NMR (b) spectrum, Figure 6 It is shown that N-tert-butyl-2-benzothiazolesulfenamide is successfully prepared in Example 2.

[0052] Figure 7 The gas chromatography (a) - mass spectrometry (b) combined spectrum of N-tert-butyl-2-benzothiazolesulfenamide prepared in Example 2, Figure 7 It is shown that the yield and molecular weight of N-tert-butyl-2-benzothiazolesulfenamide prepared in Example 2 are consistent with the theoretical values.

[0053] Figure 8 The gas chromatography (a) - mass spectrometry (b) combined spectrum of N-tert-butyl-2-benzothiazolesulfenamide prepared in Example 2, 1 H-NMR (a) and 13 C-NMR (b) spectrum, Figure 8 It is shown that N-tert-butyl-2-benzothiazolesulfenamide is successfully prepared in Example 2.

[0054] Examples 38-42

[0055] Preparation steps:

[0056] The difference from Example 2 is that the white LED light in step (1) is replaced by LED light with wavelength of 365 nm, 455 nm, 525 nm, 600 nm and 650 nm respectively; and the other steps are the same as those in Example 1.

[0057] Comparative Example 2

[0058] Preparation steps:

[0059] The difference from Example 2 is that the ionic carbon nitride photocatalyst prepared in Example 1 in step (1) is replaced by the ionic carbon nitride photocatalyst prepared in Comparative Example 1; and the other steps are the same as those in Example 1.

[0060] The raw materials and products corresponding to Examples 38-42 and Comparative Example 2 are shown in Table 2. It can be seen that the spectral absorption range of the ionic carbon nitride photocatalyst prepared by the application can reach full spectral absorption; and compared with the ionic carbon nitride photocatalyst without adding 2,4,6-triaminopyrimidine, the yield of the product can be increased from 54% to 90% under the same conditions, which effectively improves the reaction efficiency of sulfenamide compounds.

[0061]

Claims

1. An ionic carbon nitride photocatalyst, characterized in that: The catalyst is based on carbon nitride, which is doped with carbon and a metal cation, wherein the metal cation is K. + The catalyst is prepared as follows: (1) The carbon nitride precursor, potassium chloride and 2,4,6-triaminopyrimidine are mixed and ground, then dried, and then calcined at 500~600 ℃ for 3~5 h. Finally, the mixture is washed and dried to obtain the intermediate product. The molar ratio of carbon nitride precursor to potassium chloride is 1:(2~4), the mass ratio of carbon nitride precursor to 2,4,6-triaminopyrimidine is (1~8):(0~8) and the mass of 2,4,6-triaminopyrimidine is not 0. (2) The intermediate product prepared in step (1) and potassium thiocyanate are mixed and ground, and then calcined at 500~520℃ for 0.5~1.5 h under an inert atmosphere. Finally, the product is washed and dried to obtain an ionic carbon nitride photocatalyst. The mass ratio of the intermediate product to potassium thiocyanate is 1: (2~5).

2. A method for preparing an ionic carbon nitride photocatalyst as described in claim 1, characterized in that, The steps are as follows: (1) The carbon nitride precursor, potassium chloride and 2,4,6-triaminopyrimidine are mixed and ground, then dried, and then calcined at 500~600 ℃ for 3~5 h. Finally, the mixture is washed and dried to obtain the intermediate product. The molar ratio of carbon nitride precursor to potassium chloride is 1:(2~4), the mass ratio of carbon nitride precursor to 2,4,6-triaminopyrimidine is (1~8):(0~8) and the mass of 2,4,6-triaminopyrimidine is not 0. (2) The intermediate product prepared in step (1) and potassium thiocyanate are mixed and ground, and then calcined at 500~520℃ for 0.5~1.5 h under an inert atmosphere. Finally, the product is washed and dried to obtain an ionic carbon nitride photocatalyst. The mass ratio of the intermediate product to potassium thiocyanate is 1: (2~5).

3. The method for preparing the ionic carbon nitride photocatalyst as described in claim 2, characterized in that: In step (1), the carbon nitride precursor is melamine, dimelamine or urea.

4. The method for preparing the ionic carbon nitride photocatalyst as described in claim 2, characterized in that: In step (2), the second high-temperature calcination adopts a two-step heating process: first, the temperature is raised to 380~400 ℃ and held for 0.5~1.5 h, and then the temperature is raised to 500~520 ℃ and held for 0.5~1.5 h.

5. The method for preparing the ionic carbon nitride photocatalyst as described in claim 2, characterized in that: In steps (1) and (2), all drying is vacuum drying at a temperature of 40-100 °C. All washing refers to centrifugation washing several times with a mixed solvent of water and anhydrous ethanol in a volume ratio of (1-4):(6-9). The inert atmosphere is nitrogen, argon, or helium.

6. A method for photocatalytic synthesis of sulfenamide compounds using the ionic carbon nitride photocatalyst as described in claim 1, characterized in that: Thiol compounds, amine compounds, ionic carbon nitride photocatalysts, and acetonitrile were reacted under light irradiation at 0-40 °C for 5-24 h in an oxygen or air environment at 0.1-0.3 MPa. After the reaction, post-treatment was performed to obtain sulfenamide compounds.

7. The method for photocatalytic synthesis of sulfenamide compounds using an ionic carbon nitride photocatalyst as described in claim 6, characterized in that: The thiol compound is a thiol or a thiophenol; the amine compound is an aliphatic amine or an aromatic amine.

8. The method for photocatalytic synthesis of sulfenamide compounds using an ionic carbon nitride photocatalyst as described in claim 6, characterized in that: The molar ratio of thiol compound to amine compound is 1:(1~24); the molar volume ratio of thiol compound to acetonitrile is 1 mmol:(1~4) mL; and the amount of ionic carbon nitride photocatalyst is 0.5~12% of the thiol compound by mass.

9. The method for photocatalytic synthesis of sulfenamide compounds using an ionic carbon nitride photocatalyst as described in claim 6, characterized in that: The illumination is a white xenon lamp or a white LED lamp, or a light source with a wavelength of 365 nm, 455 nm, 525 nm, 600 nm, or 650 nm.

10. The method for photocatalytic synthesis of sulfenamide compounds using an ionic carbon nitride photocatalyst as described in claim 6, characterized in that, The post-processing steps are as follows: After the reaction is completed, the reaction solution is filtered, and the solid substance obtained after filtration is the catalyst. After washing and drying, it is reused. Saturated sodium chloride solution is added to the solution obtained after filtration, and then ether is added for extraction several times. The organic layer obtained after extraction is first washed with saturated sodium chloride solution, then washed with water, and then dried with anhydrous magnesium sulfate. After filtering to remove magnesium sulfate, column chromatography is performed. The eluent is a mixture of petroleum ether and ethyl acetate in a volume ratio of (10~15):

1. The obtained eluent is filtered and dried to obtain sulfonamide compounds.

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