Method for preparing sulfoxide derivative through continuous flow photocatalytic oxidation

Abstract

The invention relates to the technical field of synthesis, in particular to a method for preparing a sulfoxide derivative through continuous flow photocatalytic oxidation. The reaction formula is shown in the specification, and the method comprises the following steps: # imgabs0 #; dissolving the compound in the formula 1 and a photosensitizer in an organic solvent to obtain a mixed solution; and introducing the mixed solution and oxygen into a continuous flow photoreactor to carry out photocatalytic oxidation reaction, and after the reaction is finished, carrying out post-treatment to obtain the sulfoxide derivative as shown in the formula 2. Oxygen is adopted as an oxidizing agent for synthesis, so that the method has the advantages of few three wastes and simple post-treatment; by adopting a continuous flow preparation mode, mass transfer and heat transfer efficiency are enhanced, and the method has the characteristics of low energy consumption, high raw material utilization rate and environmental protection, and can effectively avoid resource waste.

Description

Technical Field

[0001] The present invention relates to the field of synthesis technology, and specifically, to a method for continuously preparing sulfoxide derivatives by photo-catalytic oxidation in a flowing stream. Background Art

[0002] Oxaziclomefone is a pre-emergence soil herbicide developed by Nippon Soda. Most of the disclosed preparation methods involve the oxidation of the compound of formula 1, and the preparation methods are often complex. Compared with the oxidation of sulfide derivatives to sulfone derivatives, the preparation of sulfoxide derivatives is relatively easy, which also makes it possible to prepare sulfoxide derivatives under mild conditions.

[0003] Chinese Patent CN111393427A discloses a method for preparing oxaziclomefone by oxidizing the compound of formula 1 with hydrogen peroxide as the oxidant and acid and sodium tungstate as the catalysts. This method uses an aqueous oxidant, and after the solvent is recovered, the amount of wastewater is large, which is not conducive to environmental protection. Chinese Patent CN1368965A discloses a method for preparing sulfoxide derivatives with m-chloroperbenzoic acid as the oxidant. The organic peroxide used in this method is expensive, and there is a large amount of m-chlorobenzoic acid after the reaction, which increases the difficulty of post-treatment and is not conducive to industrialization. Chinese Patent CN119143745A discloses a method for preparing oxaziclomefone with ozone as the oxidant, and its equipment and operating costs are relatively high, which is not conducive to industrialization.

[0004] Summary of the Invention

[0005] The present invention provides a method for continuously preparing sulfoxide derivatives by photo-catalytic oxidation in a flowing stream. The reaction formula is as follows, and the method includes the following steps: Dissolve the compound of formula 1 and a photosensitizer in an organic solvent to obtain a mixed solution; introduce the mixed solution and oxygen into a continuous flow photoreactor, and carry out a photo-catalytic oxidation reaction under the irradiation of LED blue light. After the reaction is completed, the sulfoxide derivative of formula 2 is obtained through post-treatment.

[0006] Optionally, dissolve the compound of formula 1 and a photosensitizer in an organic solvent, and then add an acid to obtain a mixed solution; introduce the mixed solution and oxygen into a continuous flow photoreactor, and carry out a photo-catalytic oxidation reaction under the irradiation of LED blue light. After the reaction is completed, the sulfoxide derivative of formula 2 is obtained through post-treatment.

[0007] The photosensitizer includes one or more combinations of acetophenone, benzophenone, anthraquinone, 2,3-butanedione, and porphyrin derivatives.

[0008] Optionally, the photosensitizer includes one or more combinations of acetophenone, 2,3-butanedione, and porphyrin derivatives.

[0009] Optionally, the porphyrin derivative includes 5,10,15,20-tetrakis(4-nitrophenyl)porphyrin.

[0010] The organic solvent includes one or more combinations of alcohols, nitriles, carboxylic acids, carboxylic acid esters, and halogenated hydrocarbons.

[0011] Optionally, the organic solvent is one of nitriles and alcohols.

[0012] The acid includes one or more combinations of formic acid, acetic acid, propionic acid, butyric acid, sulfuric acid, and phosphoric acid.

[0013] The molar ratio of the compound of Formula 1, photosensitizer, acid, and oxygen is 1:(0.01 - 0.1):(0.01 - 0.1):(1 - 3).

[0014] Optionally, the molar ratio of the compound of Formula 1, photosensitizer, acid, and oxygen is 1:(0.02 - 0.05):(0.01 - 0.03):(1 - 2).

[0015] By defining the molar ratio of the compound of Formula 1, photosensitizer, acid, and oxygen as 1:(0.01 - 0.1):(0.01 - 0.1):(1 - 3), the product purity can be increased to 97%. Under LED blue light irradiation, the photosensitizer absorbs light energy and transitions from the ground state to the excited state. A specific content of the photosensitizer can efficiently transfer electrons to oxygen to generate superoxide anion radicals, while the photosensitizer is oxidized to the photosensitizer cation radical. The addition of a specific acid may help stabilize the active species in the reaction system, promote the reaction, and at the same time, the acid can provide protons to help the superoxide anion radical transform into hydrogen peroxide, or adjust the pH value of the reaction system to reduce the formation of by-products.

[0016] The reaction time of the photocatalytic oxidation reaction is 0.1 - 5 h.

[0017] Optionally, the reaction time of the photocatalytic oxidation reaction is 0.75 - 2 h.

[0018] Beneficial Effects

[0019] 1. By selecting one or more combinations of acetophenone, 2,3-butanedione, and porphyrin derivatives as the photosensitizer and performing the photocatalytic oxidation reaction under LED blue light irradiation, side reactions can be reduced and the product purity can be improved.

[0020] 2. By defining the molar ratio of the compound of Formula 1, photosensitizer, acid, and oxygen as 1:(0.01 - 0.1):(0.01 - 0.1):(1 - 3), the product purity can be increased to 97%.

[0022] 3. By limiting the reaction time of the photocatalytic oxidation reaction to 0.1 - 5 h, the product yield can be further increased to 97%.

[0024] 4. The synthesis method provided by the present invention uses oxygen as an oxidant, and the raw materials are cheap and easily available, with the advantages of less three wastes and simple post-treatment.

[0025] 5. The present invention adopts a continuous flow preparation method, which strengthens the mass transfer and heat transfer efficiency, has the characteristics of low energy consumption, high raw material utilization rate and environmental friendliness, and can effectively avoid resource waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is the NMR spectrum of the compound of formula 1 in Example 1.

[0027] Figure 2 It is the NMR spectrum of the sulfoxide derivative in Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0028] Example 1

[0029] A method for continuously flowing photocatalytic oxidation to prepare a sulfoxide derivative, the reaction formula is as follows, and the steps are as follows:

[0030] Dissolve the compound of formula 1 (0.49 mol) and acetophenone (9.8 mmol) in 450 g of acetonitrile, add formic acid (9.8 mmol) to form a solution, pump this solution into a continuous flow photoreactor with a metering pump, and simultaneously introduce oxygen. Under the irradiation of LED blue light (450 ± 10 nm), carry out the oxidation reaction at room temperature (25 °C), keep the residence time in the reactor at 45 min, the solution flow rate at 14 g / min, and the oxygen flow rate at 0.52 g / min. After the reaction is completed, through post-treatment (negative pressure desolvation, filtration, drying), the white solid sulfoxide derivative of formula 2 can be obtained.

[0031] The photosensitizer is acetophenone.

[0032] Example 2

[0033] A method for continuously flowing photocatalytic oxidation to prepare a sulfoxide derivative, the reaction formula is as follows, and the steps are as follows:

[0034] Dissolve the compound of formula 1 (0.49 mol) and acetophenone (9.8 mmol) in 450 g of acetic acid to form a solution. Pump this solution into a continuous flow photoreactor using a metering pump, while introducing oxygen. Under the irradiation of blue LED light, carry out the oxidation reaction at room temperature (25 °C), maintaining a residence time of 45 min in the reactor, a solution flow rate of 14 g / min, and an oxygen flow rate of 0.52 g / min. After the reaction is completed, through post-treatment, a white solid sulfoxide derivative of formula 2 can be obtained.

[0035] The photosensitizer is acetophenone.

[0036] Example 3

[0037] A method for continuously flowing photocatalytic oxidation to prepare a sulfoxide derivative, the reaction formula is as follows, and the steps are as follows:

[0038] Dissolve the compound of formula 1 (0.49 mol) and 2,3-butanedione (14.7 mmol) in 450 g of ethyl acetate, add acetic acid (9.8 mmol) to form a solution. Pump this solution into a continuous flow photoreactor using a metering pump, while introducing oxygen. Under the irradiation of blue LED light, carry out the oxidation reaction at room temperature (25 °C), maintaining a residence time of 60 min in the reactor, a solution flow rate of 10.5 g / min, and an oxygen flow rate of 0.52 g / min. After the reaction is completed, through post-treatment, a white solid sulfoxide derivative of formula 2 can be obtained.

[0039] The photosensitizer is 2,3-butanedione.

[0040] Example 4

[0041] A method for continuously flowing photocatalytic oxidation to prepare a sulfoxide derivative, the reaction formula is as follows, and the steps are as follows:

[0042] Dissolve the compound of formula 1 (0.49 mol) and 2,3-butanedione (14.7 mmol) in 450 g of dichloromethane, add sulfuric acid (14.7 mmol) to form a solution. Pump this solution into a continuous flow photoreactor using a metering pump, while introducing oxygen. Under the irradiation of blue LED light, carry out the oxidation reaction at room temperature (25 °C), maintaining a residence time of 60 min in the reactor, a solution flow rate of 10.5 g / min, and an oxygen flow rate of 0.52 g / min. After the reaction is completed, through post-treatment, a white solid sulfoxide derivative of formula 2 can be obtained.

[0043] The photosensitizer is 2,3-butanedione.

[0044] Example 5

[0045] A method for preparing sulfoxide derivatives by continuous flow photocatalytic oxidation, the reaction formula is as follows, and the steps are as follows:

[0046] Dissolve the compound of formula 1 (0.49 mol) and 5,10,15,20-tetrakis(4-nitrophenyl)porphyrin (4.9 mmol) in 450 g of methanol, add sulfuric acid (14.7 mmol) to form a solution, pump this solution into a continuous flow photoreactor with a metering pump, and simultaneously introduce oxygen. Under the irradiation of LED blue light, carry out the oxidation reaction at room temperature (25 °C), keep the residence time in the reactor at 90 min, the solution flow rate at 7 g / min, and the oxygen flow rate at 0.26 g / min. After the reaction is completed, the white solid sulfoxide derivative of formula 2 can be obtained through post-treatment.

[0047] The photosensitizer is 5,10,15,20-tetrakis(4-nitrophenyl)porphyrin.

[0048] Example 6

[0049] A method for preparing sulfoxide derivatives by continuous flow photocatalytic oxidation, the reaction formula is as follows, and the steps are as follows:

[0050] Dissolve the compound of formula 1 (0.49 mol) and 5,10,15,20-tetrakis(4-nitrophenyl)porphyrin (4.9 mmol) in 450 g of methanol, add phosphoric acid (9.8 mmol) to form a solution, pump this solution into a continuous flow photoreactor with a metering pump, and simultaneously introduce oxygen. Under the irradiation of LED blue light, carry out the oxidation reaction at room temperature (25 °C), keep the residence time in the reactor at 90 min, the solution flow rate at 7 g / min, and the oxygen flow rate at 0.44 g / min. After the reaction is completed, the white solid sulfoxide derivative of formula 2 can be obtained through post-treatment.

[0051] The photosensitizer is 5,10,15,20-tetrakis(4-nitrophenyl)porphyrin.

[0052] Comparative Example 1

[0053] A method for preparing sulfoxide derivatives by continuous flow photocatalytic oxidation, the reaction formula is as follows, and the steps are as follows:

[0054] Dissolve the compound of formula 1 (0.49 mol) and 2,3-butanedione (14.7 mmol) in 450 g of acetonitrile, add acetic acid (24.5 mmol) to form a solution. Pump this solution into a continuous flow photoreactor using a metering pump, while introducing oxygen. Conduct the oxidation reaction at room temperature (25 °C) in the dark, maintaining a residence time of 45 min in the reactor, a solution flow rate of 14 g / min, and an oxygen flow rate of 0.52 g / min. After the reaction, the sulfoxide derivative of formula 2 was not obtained.

[0055] The photosensitizer is 2,3-butanedione.

[0056] Comparative Example 2

[0057] A method for continuously flowing photocatalytic oxidation to prepare a sulfoxide derivative, the reaction formula is as follows, and the steps are as follows:

[0058] Dissolve the compound of formula 1 (0.49 mol) in 450 g of acetonitrile, add acetic acid (24.5 mmol) to form a solution. Pump this solution into a continuous flow photoreactor using a metering pump, while introducing oxygen. Conduct the oxidation reaction at room temperature (25 °C) under the irradiation of LED blue light, maintaining a residence time of 45 min in the reactor, a solution flow rate of 14 g / min, and an oxygen flow rate of 0.52 g / min. After the reaction, the sulfoxide derivative of formula 2 was not obtained.

[0059] Comparative Example 3

[0060] A method for continuously flowing photocatalytic oxidation to prepare a sulfoxide derivative, the reaction formula is as follows, and the steps are as follows:

[0061] Dissolve the compound of formula 1 (0.49 mol) and acetophenone (9.8 mmol) in 450 g of acetic acid to form a solution. Pump this solution into a continuous flow photoreactor using a metering pump, while introducing oxygen. Conduct the oxidation reaction at room temperature (25 °C) under the irradiation of sunlight, maintaining a residence time of 90 min in the reactor, a solution flow rate of 7 g / min, and an oxygen flow rate of 0.35 g / min. After the reaction, the white solid sulfoxide derivative of formula 2 can be obtained after post-treatment.

[0062] The photosensitizer is acetophenone.

[0063] Performance testing method

[0064] Perform 1 1H NMR testing on the compound of formula 1 and the sulfoxide derivative in Example 1, as Figure 1 shown, the spectral characterization results: 11H NMR (400 MHz, CDCl3) δ 6.72 (t, J = 72.0 Hz, 1H), 4.18 (s, 2H), 3.82 (s, 2H), 2.78 (s, 2H), 1.42 (s, 6H); As Figure 2 shown, the characterization results of the spectrum are: 1 1H NMR (400 MHz, CDCl3) δ 6.95 (dd, 1H), 4.16 (s, 2H), 3.86 (s, 3H), 3.15 (q, 2H), 1.52 (d, 6H).

[0065] The yields and purities in the examples and comparative examples were tested, and the test data are listed in Table 1. Among them, no products were obtained in Comparative Examples 1 and 2, which were indicated by " / ".

[0066] Performance test data

[0067] Table 1

[0068] Yield % Purity % Example 1 98.2 98.8 Example 2 98.3 98.5 Example 3 97.9 98.7 Example 4 99.2 98.3 Example 5 98.5 99.2 Example 6 98.6 99.1 Comparative Example 1 / / Comparative Example 2 / / Comparative Example 3 32.5 74.2

Claims

1. A method for preparing sulfoxide derivatives by continuous flow photocatalytic oxidation, characterized in that, The reaction formula is as follows: It includes the following steps: Dissolve the compound of formula 1 and the photosensitizer in an organic solvent to obtain a mixed solution; introduce the mixed solution and oxygen into a continuous flow photoreactor, and carry out a photocatalytic oxidation reaction under the irradiation of blue LED light. After the reaction is completed, the sulfoxide derivative of formula 2 is obtained through post-treatment.

2. The method for continuously preparing sulfoxide derivatives by photoflow catalyzed oxidation according to claim 1, wherein Dissolve the compound of formula 1 and the photosensitizer in an organic solvent, and then add an acid to obtain a mixed solution; introduce the mixed solution and oxygen into a continuous flow photoreactor, and carry out photocatalytic oxidation reaction under the irradiation of blue LED light. After the reaction is completed, the sulfoxide derivative of formula 2 is obtained through post-treatment.

3. The method for preparing sulfoxide derivatives by continuous flow photocatalytic oxidation according to claim 1, characterized in that, The photosensitizer includes one or more combinations of acetophenone, benzophenone, anthraquinone, 2,3-butanedione, and porphyrin derivatives.

4. The method for continuously preparing sulfoxide derivatives by streamer photocatalytic oxidation according to claim 3, characterized in that, The photosensitizer includes one or more combinations of acetophenone, 2,3-butanedione, and porphyrin derivatives.

5. The method for continuously preparing sulfoxide derivatives by photoflow catalyzed oxidation according to claim 1, characterized in that, The organic solvent includes one or more combinations of alcohols, nitriles, carboxylic acids, carboxylic acid esters, and halogenated hydrocarbons.

6. The method for continuously preparing sulfoxide derivatives by photoflow catalyzed oxidation according to claim 2, wherein The acid includes one or more combinations of formic acid, acetic acid, propionic acid, butyric acid, sulfuric acid, and phosphoric acid.

7. The method for continuously preparing sulfoxide derivatives by streamer photocatalysis oxidation according to claim 6, wherein The molar ratio of the compound of formula 1, the photosensitizer, the acid, and oxygen is 1:(0.01 - 0.1):(0.01 - 0.1): (1～3)。 8. The method for preparing sulfoxide derivatives by continuous flow photocatalytic oxidation according to claim 7, characterized in that, The molar ratio of the compound of formula 1, the photosensitizer, the acid, and oxygen is 1:(0.02 - 0.05):(0.01 - 0.03): (1～2)。 9. The method for continuously preparing sulfoxide derivatives by photoflow catalyzed oxidation according to claim 1, characterized in that, The reaction time of the photocatalytic oxidation reaction is 0.1 - 5 h.

10. The method for continuously preparing sulfoxide derivatives by streamer photocatalytic oxidation according to claim 9, characterized in that, The reaction time of the photocatalytic oxidation reaction is 0.75 - 2 h.

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