A method for ultraviolet light driven molybdenum diselenide nanocarbon material heterogeneous catalysis reduction of nitroaromatic hydrocarbons

Abstract

The present invention develops a new method for selective reduction of nitroaromatics by heterogeneous catalysis under ultraviolet light drive. The method designs, synthesizes and uses a new type of molybdenum diselenide nanocarbon material as a catalyst for the reaction, uses nitroaromatics as a raw material, and isopropanol as a reaction hydrogen source, and carries out heterogeneous catalytic reduction driven by ultraviolet light under room temperature, and can successfully reduce nitroaromatics to corresponding aromatic amines. The method has the advantages of mild reaction conditions, simple reaction operation, and less reaction pollution.

Description

Technical Field

[0001] The invention relates to a method for light-driven heterogeneous catalytic reduction of nitroaromatics, and in particular to a method for ultraviolet light-driven heterogeneous catalytic reduction of nitroaromatics by molybdenum diselenide nanocarbon materials, and belongs to the field of organic photochemistry and heterogeneous catalysis. Background Art

[0002] Nitrogen-containing compounds are bulk chemicals, specialty chemicals and pharmaceuticals with important commercial value. They are widely present in existing substances in nature and have good biological activity. Organic nitrogen-containing compounds can be roughly divided into nitro compounds, amine compounds, nitriles and isonitriles, among which nitro compounds and amine compounds are two very important branches of organic nitrogen-containing compounds. Nitro compounds can be used in the industrial production of explosives, chemical fibers, rubber and other products. Amine compounds can be used in the production of agricultural chemicals, surfactants and polymers. Therefore, the research on nitro compounds and amine compounds is of great significance.

[0003] Molybdenum diselenide (MoSe2) is a narrow bandgap semiconductor material. Its absorption of light can extend to the infrared region, which enables it to make full use of sunlight. At the same time, MoSe2 is also a type of material with good anti-photocorrosion stability. These advantages make MoSe2 have potential value in photocatalytic applications. However, there are still few reports on the use of MoSe2 for photocatalytic applications. This is mainly due to the fact that MoSe2 is easy to aggregate and it is easy to form photogenerated electron-hole pairs with relatively high recombination with photogenerated electrons. The photocatalytic activity of MoSe2 is limited, thus limiting its photocatalytic application. According to literature reports, the photocatalytic activity of MoSe2 can be improved by constructing a heterojunction. The construction of a heterojunction can effectively separate and transfer photogenerated electrons and hole pairs. Commonly used methods for constructing heterojunctions include: compounding MoSe2 with carbon materials such as graphene oxide and carbon nanofibers, or compounding with semiconductor materials such as NiSe, ZnIn2S4, and HfS2. At present, a preparation process of a molybdenum diselenide nanocarbon material has been disclosed [reference: CN202210476918.8]. We envision using the molybdenum diselenide nanocarbon material as a heterogeneous catalyst to design a photocatalytic selective reduction method for nitroaromatics. Summary of the invention

[0004] Different from the existing heterogeneous catalytic nitro reduction method, we have developed a UV-driven molybdenum diselenide nanocarbon material heterogeneous catalytic nitroaromatic reduction method. This method uses molybdenum diselenide nanocarbon material as a catalyst, nitroaromatics as a raw material, and isopropanol as a reaction hydrogen source. Under room temperature, the heterogeneous photocatalytic reduction of nitroaromatics can be achieved by ultraviolet light irradiation.

[0005] In order to achieve the above-mentioned object of the invention, the present invention proposes the following technical solutions:

[0006]

[0007] This scheme uses nitroaromatic hydrocarbon I as a raw material, uses isopropanol as a solvent, adds maleic acid as a reaction additive, and performs a selective nitro reduction reaction under ultraviolet light irradiation at room temperature to obtain aromatic amine II in the presence of molybdenum diselenide catalyst.

[0008] As a preferred embodiment, the nitroaromatic hydrocarbon I has a structure shown in Formula 1:

[0009]

[0010] Wherein, Ar is various substituted phenyl groups and various substituted naphthyl groups. In the nitroaromatics of the present invention, Ar can be various substituted phenyl groups, including monosubstituted phenyl groups and polysubstituted phenyl groups, and the positions of the substituents are not limited, such as phenyl groups substituted by methyl, ethyl, chlorine atoms, etc. at the 2nd position, and phenyl groups disubstituted by methyl groups at the 3rd and 4th positions, etc. Ar can be various monosubstituted naphthyl groups, and the positions of the substituents are not limited.

[0011] As a preferred solution, the aromatic amine II has a structure as shown in Formula 2:

[0012]

[0013] Wherein, Ar is various substituted phenyl groups and various substituted naphthyl groups. In the nitroaromatics of the present invention, Ar can be various substituted phenyl groups, including monosubstituted phenyl groups and polysubstituted phenyl groups, and the positions of the substituents are not limited, such as phenyl groups substituted by methyl, ethyl, chlorine atoms, etc. at the 2nd position, and phenyl groups disubstituted by methyl groups at the 3rd and 4th positions, etc. Ar can be various monosubstituted naphthyl groups, and the positions of the substituents are not limited.

[0014] As a preferred solution, the amount of the molybdenum diselenide catalyst is 3% to 14% of the nitroaromatic reaction equivalent. The increase in the amount of the molybdenum diselenide catalyst has a more obvious improvement in the yield of the target product. When the amount of the molybdenum diselenide catalyst exceeds 10% of the nitroaromatic reaction equivalent, the yield of the target product is not significantly improved.

[0015] As a preferred solution, the amount of maleic acid used is 0.5 to 1 times the reaction equivalent of nitroaromatic hydrocarbons. After adding maleic acid, the yield of the target product is significantly improved. When the amount of maleic acid used reaches 0.5 times the reaction equivalent of 2 nitroaromatic hydrocarbons, the yield of the target product of the reaction is good. As the amount of maleic acid increases, the yield of the target product begins to decrease.

[0016] As a preferred solution, the solvent used in the reaction is isopropanol. When other solvents such as methanol, ethanol, and 1,4-dioxane are used, the yield of the target product is poor.

[0017] The specific reaction principle of the ultraviolet-driven molybdenum diselenide nanocarbon material heterogeneously catalyzed selective reduction reaction of nitroaromatics of the present invention may be as follows: isopropanol releases hydrogen to generate acetone under the conditions of light and the presence of molybdenum diselenide catalyst. Nitrobenzene is reduced by combining with the hydrogen released by isopropanol to generate nitrosobenzene, which is further reduced by hydrogenation to phenylhydroxylamine, and finally phenylhydroxylamine is reduced by combining with the hydrogen released by isopropanol to obtain aniline. Compared with the prior art, the technical solution of the present invention has the following advantages:

[0018] First, the method is tolerant to a wide range of functional groups;

[0019] Second, the method is simple, mild, green, and effective for the synthesis of aromatic amines;

[0020] Third, this method only requires one step of reaction, and the yield of the target product can reach 66%.

[0021] Fourth, this method has certain feasibility for industrial large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The proposed method for the selective reduction of nitroaromatics by heterogeneous catalysis of molybdenum diselenide nanocarbon materials driven by ultraviolet light; Figure 2 is the H NMR spectrum of aniline; Figure 3 This is the carbon NMR spectrum of aniline. DETAILED DESCRIPTION

[0023] In order to make the above-mentioned features, advantages and purposes of the present invention more clear and easy to understand, the content of the present invention is described in detail below in conjunction with specific embodiments. Many specific details are set forth in the above description to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific implementation disclosed below.

[0024] The reaction raw materials and catalysts involved in the following examples, unless otherwise specified, are conventional commercially available reagents on the market.

[0025] Condition optimization experiment: Taking the light-driven selective reduction of nitrobenzene as an example, the optimal reaction conditions were obtained by optimizing the amount of catalyst, solvent selection, acid / base selection and dosage, reaction time and light source, and monitoring the reaction yield by gas chromatography. The specific reaction under the optimal reaction conditions is as follows:

[0026] In a 10mL reaction tube, 0.2mmol of nitrobenzene, 0.02mmol of molybdenum diselenide catalyst, and 0.1mmol of maleic acid were added, and 3.0mL of isopropanol was added as a solvent. The reaction was carried out for 12 hours under room temperature with a power of 72W and a wavelength of 365-375nm ultraviolet light. After the reaction was completed, diphenyl ether was added as an internal standard, and the supernatant was separated after sufficient shaking and centrifugation. The conversion rate of nitrobenzene was>99%, and the selectivity of aniline was 66%. The target product aniline was obtained by column chromatography separation using a proportioning solvent of petroleum ether and ethyl acetate, and a light yellow oily liquid was obtained.

[0027]

[0028]

[0029] It can be seen from experimental groups 1 to 5 in the above table that as the amount of molybdenum diselenide catalyst increases, the selectivity of the target product of the reaction also increases. When the amount of molybdenum diselenide catalyst reaches 10% to 14% of the nitrobenzene reaction equivalent, the selectivity of the target product of the reaction is good.

[0030] It can be seen from the experimental groups 1 and 6 to 12 in the above table that isopropanol is a better reaction solvent, and a higher reactant conversion rate and target product selectivity can be obtained when reacting in this solvent.

[0031] It can be seen from experimental groups 1 and 13-16 in the above table that the reaction will not occur without light, and the reactant conversion rate and the target product selectivity will be significantly affected as the wavelength of light changes. When the wavelength of light is between 365-375nm and the light power reaches 72W, the reactant conversion rate and the target product selectivity are better.

[0032] From the experimental groups 1 and 17-25 in the above table, it can be seen that maleic acid plays a positive role in promoting the formation of the target product, but with the increase of the amount of maleic acid added, the selectivity of the target product shows a trend of first increasing and then decreasing. When 0.1 mmol of acetic acid is added, the yield of the target product of the reaction is better. Sodium bicarbonate, sodium dihydrogen phosphate and oxalic acid do not have a strong promoting effect on the formation of the target product as maleic acid.

[0033] It can be seen from experimental groups 1 and 26-27 in the above table that the reaction time will affect the reactant conversion rate and the target product selectivity of the reaction. When the reaction time increases, the reactant conversion rate and the target product selectivity will also increase. When the reaction time reaches 12h, the reactant conversion rate and the target product selectivity are better.

[0034] The present invention is further described below in conjunction with specific preparation examples 1 to 11:

[0035] Preparation Example 1

[0036] In a 10mL reaction tube, 0.2mmol of nitrobenzene, 0.02mmol of molybdenum diselenide catalyst, and 0.1mmol of maleic acid were added, and 3.0mL of isopropanol was added as a solvent. The reaction was carried out for 12 hours under room temperature with a power of 72W and a wavelength of 365-375nm ultraviolet irradiation. After the reaction was completed, diphenyl ether was added as an internal standard, and the supernatant was separated after sufficient shaking and then centrifuged. The conversion rate of nitrobenzene was >99%, and the selectivity of aniline was 66%. The target product aniline was obtained by column chromatography separation, and a light yellow oily liquid was obtained.

[0037] 1 H NMR (400MHz, CDCl3) δ7.21–7.14(m,2H),6.78(tt,J=7.4,1.1Hz,1H),6.73–6.67(m,2H),3.52(s,2H).

[0038] 13 C NMR (101MHz, CDCl3) δ146.4,129.3,118.6,115.2.

[0039] Preparation Example 2

[0040] 2-nitrotoluene 0.2mmol, molybdenum diselenide catalyst 0.02mmol, maleic acid 0.1mmol were added to a 10mL reaction tube, 3.0mL isopropanol was added as a solvent, and the reaction was carried out for 12h under room temperature with a power of 72W and a wavelength of 365-375nm ultraviolet light. After the reaction was completed, diphenyl ether was added as an internal standard, centrifuged after full concussion, the supernatant was separated, and a gas chromatograph was used to detect that the conversion rate of 2-nitrotoluene was 63%, and the selectivity of 2-methylaniline was 25%. The target product 2-methylaniline was obtained by column chromatography, and an orange oily liquid was obtained.

[0041] 1 H NMR (400MHz, CDCl3) δ7.17(t,J=7.4Hz,2H),6.84(t,J=7.4Hz,1H),6.76(d,J=7.9Hz,1H),3.62(s,2H),2.27(s,3H).

[0042] 13 C NMR (101MHz, CDCl3) δ144.8,130.6,127.1,122.4,118.7,115.1,17.5. Preparation Example 3

[0043] 4-nitrotoluene 0.2mmol, molybdenum diselenide catalyst 0.02mmol, maleic acid 0.1mmol were added to a 10mL reaction tube, 3.0mL isopropanol was added as a solvent, and the reaction was carried out for 12h under room temperature with a power of 72W and a wavelength of 365-375nm ultraviolet irradiation. After the reaction was completed, diphenyl ether was added as an internal standard, centrifuged after sufficient shaking, the supernatant was separated, and a gas chromatograph was used to detect that the conversion rate of 4-nitrotoluene was>99%, and the selectivity of 4-methylaniline was 39%. The target product 4-methylaniline was obtained by column chromatography separation, and a light yellow solid was obtained.

[0044] 1 H NMR (400MHz, CDCl3) δ7.01 (d, J = 7.9 Hz, 2H), 6.64 (d, J = 8.0 Hz, 2H), 3.48 (s, 2H), 2.28 (s, 3H).

[0045] 13 C NMR (101MHz, CDCl3) δ143.9,129.8,127.8,115.3,20.5.

[0046] Preparation Example 4

[0047] 0.2mmol of 2-nitroethylbenzene, 0.02mmol of molybdenum diselenide catalyst, 0.1mmol of maleic acid were added to a 10mL reaction tube, and 3.0mL of isopropanol was added as a solvent. The reaction was carried out for 12 hours under room temperature with a power of 72W and a wavelength of 365-375nm ultraviolet irradiation. After the reaction was completed, diphenyl ether was added as an internal standard, and the supernatant was separated after sufficient shaking. The gas chromatograph was used to detect that the conversion rate of 2-nitroethylbenzene was 57%, and the selectivity of 2-ethylaniline was 20%. The target product aniline was obtained by column chromatography separation, and a light yellow oily liquid was obtained.

[0048] 1 H NMR (400MHz, CDCl3) δ7.19–7.10(m,2H),6.85(t,J=7.4Hz,1H),6.75(d,J=7.8Hz,1H),3.63(s,2H),2.59(q,J=7.5Hz,2H),1.34(t,J=7.3Hz,3H).

[0049] 13 C NMR (101MHz, CDCl3) δ144.1,128.4,128.2,126.9,118.9,115.5,24.1,13.1.

[0050] Preparation Example 5

[0051] 0.2 mmol of 3-nitrobenzotrifluoride, 0.02 mmol of molybdenum diselenide catalyst, 0.1 mmol of maleic acid were added to a 10 mL reaction tube, and 3.0 mL of isopropanol was added as a solvent. The reaction was carried out for 12 hours under room temperature with a power of 72 W and a wavelength of 365-375 nm ultraviolet irradiation. After the reaction was completed, diphenyl ether was added as an internal standard, and the supernatant was separated after sufficient shaking and then centrifuged. The supernatant was detected by gas chromatograph, and the conversion rate of 3-nitrobenzotrifluoride was 90%, and the selectivity of 3-trifluoromethylaniline was 50%. The target product aniline was obtained by column chromatography separation, and a light yellow oily liquid was obtained.

[0052] 1 H NMR (400MHz, CDCl3) δ7.24(t,J=7.9Hz,1H),7.00(d,J=7.7Hz,1H),6.89(s,1H),6.80(d,J=8.1Hz,1H),3.82(s,2H).

[0053] 13 C NMR (101MHz, CDCl3) δ146.8,131.7,131.4,131.1,129.8,128.4,125.7,123.0,120 .3,118.1,118.0,117.9,115.1,115.0,114.9,114.8,111.5,111.4,111.3,111.2.

[0054] 19 F NMR (376MHz, CDCl3) δ-62.8.

[0055] Preparation Example 6

[0056] 0.2 mmol of 3-nitrobenzonitrile, 0.02 mmol of molybdenum diselenide catalyst, 0.1 mmol of maleic acid were added to a 10 mL reaction tube, and 3.0 mL of isopropanol was added as a solvent. The reaction was carried out for 12 hours under room temperature with a power of 72 W and a wavelength of 365-375 nm ultraviolet light. After the reaction was completed, diphenyl ether was added as an internal standard, and the supernatant was separated after sufficient shaking and then centrifuged. The conversion rate of 3-nitrobenzonitrile was> 99%, and the selectivity of 3-cyanoaniline was 74%. The target product aniline was obtained by column chromatography separation, and a brown solid was obtained.

[0057] 1H NMR (400MHz, CDCl3) δ7.21(t,J=7.9Hz,1H),7.00(dt,J=7.5,1.3Hz,1H),6.91–6.84(m,2H),3.92(s,2H).

[0058] 13 C NMR (101MHz, CDCl3) δ146.9,130.0,121.8,119.2,119.1,117.3,112.8. Preparation Example 7

[0059] 0.2 mmol of 2-chloronitrobenzene, 0.02 mmol of molybdenum diselenide catalyst, and 0.1 mmol of maleic acid were added to a 10 mL reaction tube, and 3.0 mL of isopropanol was added as a solvent. The reaction was carried out for 12 hours under room temperature with a power of 72 W and a wavelength of 365-375 nm ultraviolet light. After the reaction was completed, diphenyl ether was added as an internal standard, and the supernatant was separated after sufficient shaking and detected by gas chromatograph. The conversion rate of 2-chloronitrobenzene was 64%, and the selectivity of 2-chloroaniline was 35%. The target product aniline was obtained by column chromatography, and a brown oily liquid was obtained.

[0060] 1 H NMR (400MHz, CDCl3) δ7.28 (s, 1H), 7.08 (t, J = 7.7Hz, 1H), 6.79–6.68 (m, 2H), 4.00 (s, 2H).

[0061] 13 C NMR (101MHz, CDCl3) δ143.0,129.5,127.7,119.3,119.1,116.0.

[0062] Preparation Example 8

[0063] 0.2 mmol of 3,4-dimethylnitrobenzene, 0.02 mmol of molybdenum diselenide catalyst, 0.1 mmol of maleic acid were added to a 10 mL reaction tube, and 3.0 mL of isopropanol was added as a solvent. The reaction was carried out for 12 hours under room temperature with ultraviolet irradiation of 72 W and a wavelength of 365-375 nm. After the reaction was completed, diphenyl ether was added as an internal standard, and the supernatant was separated after sufficient shaking and centrifugation. The conversion rate of 3,4-dimethylnitrobenzene was >99%, and the selectivity of 3,4-dimethylaniline was 66%. The target product aniline was obtained by column chromatography separation as a light yellow solid.

[0064] 1H NMR (400MHz, CDCl3) δ7.04(d,J=7.9Hz,1H),6.60(d,J=2.5Hz,1H),6.55(dd,J=7.9,2.5Hz,1H),3.56(s,2H),2.30(d,J=8.5Hz,6H).

[0065] 13 C NMR (101MHz, CDCl3) δ144.5,137.5,130.4,126.5,117.0,112.8,20.0,18.9.

[0066] Preparation Example 9

[0067] 5-chloro-2-nitrobenzoic acid methyl ester 0.2mmol, molybdenum diselenide catalyst 0.02mmol, maleic acid 0.1mmol were added to a 10mL reaction tube, 3.0mL isopropanol was added as a solvent, and the reaction was carried out for 12h by ultraviolet irradiation with a power of 72W and a wavelength of 365-375nm at room temperature. After the reaction was completed, diphenyl ether was added as an internal standard, centrifuged after full concussion, and the supernatant was separated, and a gas chromatograph was used to detect that the conversion rate of 5-chloro-2-nitrobenzoic acid methyl ester was 89%, and the selectivity of 5-chloro-2-aminobenzoic acid methyl ester was 65%. By column chromatography separation, the target product aniline was obtained, and a light yellow solid was obtained.

[0068] 1 H NMR (400MHz, CDCl3) δ7.84–7.79(m,1H),7.27–7.16(m,1H),6.60(dd,J=8.9,3.7Hz,1H),5.73(s,2H),3.86(d,J=4.0Hz,3H).

[0069] 13 C NMR (101MHz, CDCl3) δ167.6,148.9,134.0,130.4,120.6,118.0,111.4,51.8.

[0070] Preparation Example 10

[0071] 1-nitronaphthalene 0.2mmol, molybdenum diselenide catalyst 0.02mmol, maleic acid 0.1mmol were added to 10mL reaction tubes, 3.0mL isopropanol was added as solvent, and the reaction was carried out for 12h by ultraviolet irradiation with a power of 72W and a wavelength of 365-375nm at room temperature. After the reaction was completed, diphenyl ether was added as internal standard, centrifuged after full concussion, and the supernatant was isolated, and gas chromatograph was used to detect that the conversion rate of 1-nitronaphthalene was 55%, and the selectivity of 1-naphthylamine was 21%. By column chromatography separation, the target product aniline was obtained, and a brown solid was obtained.

[0072] 1 H NMR (400MHz, CDCl3) δ7.87–7.80(m,2H),7.53–7.45(m,2H),7.38–7.29(m,2H),6.80(d,J=6.9Hz,1H),4.15(s,2H).

[0073] 13 C NMR (101MHz, CDCl3) δ142.1,134.4,128.6,126.4,125.9,124.9,123.7,120.9,119.0,109.7.

[0074] Preparation Example 11

[0075] 2-methyl-1-nitronaphthalene 0.2mmol, molybdenum diselenide catalyst 0.02mmol, maleic acid 0.1mmol were added to a 10mL reaction tube, 3.0mL isopropanol was added as a solvent, and the reaction was carried out for 12h by ultraviolet irradiation with a power of 72W and a wavelength of 365-375nm at room temperature. After the reaction was completed, diphenyl ether was added as an internal standard, centrifuged after full concussion, and the supernatant was isolated, and a gas chromatograph was used to detect that the conversion rate of 2-methyl-1-nitronaphthalene was 51%, and the selectivity of 2-methyl-1-naphthylamine was 24%. By column chromatography separation, the target product aniline was obtained, and a brown oily liquid was obtained.

[0076] 1 H NMR (400MHz, CDCl3) δ8.15(d,J=8.2Hz,1H),7.80(d,J=7.9Hz,1H),7.52–7.39(m,3H),7.28(s,1H),2.44(s,3H).

[0077] 13C NMR(101MHz,CDCl3)δ148.56,133.40,129.01,127.66,125.41,125.31,124.24,120.91,120.16,116.27,15.71.

Claims

1. A method for ultraviolet light driven molybdenum diselenide nanocarbon material heterogeneous catalytic reduction of nitroaromatic hydrocarbons, characterized in that: The photocatalytic reduction method of nitroaromatics is as follows: Using nitroaromatic hydrocarbon I as a raw material, in the presence of molybdenum diselenide nanocarbon material, using isopropanol as a solvent, adding maleic acid as a reaction additive, and performing a selective nitro reduction reaction under ultraviolet light irradiation at room temperature to obtain aromatic amine II; Wherein, nitroaromatic hydrocarbon I is nitrobenzene, 2-nitrotoluene, 4-nitrotoluene, 2-nitroethylbenzene, 3-nitrotrifluorotoluene, 3-nitrobenzenenitrile, 2-chloronitrobenzene, 3,4-dimethylnitrobenzene, 5-chloro-2-nitrobenzoic acid methyl ester, 1-nitronaphthalene or 2-methyl-1-nitronaphthalene.

2. The method for reducing nitroaromatic hydrocarbons by ultraviolet light-driven molybdenum diselenide nanocarbon materials in heterogeneous catalysis according to claim 1, characterized in that: The dosage of the molybdenum diselenide nano-carbon material catalyst is 3% to 10% of the reaction equivalent of nitroaromatic hydrocarbon I; the dosage of the maleic acid is 0.5 to 1 times of the reaction equivalent of nitroaromatic hydrocarbon I.

3. The method for reducing nitroaromatic hydrocarbons by ultraviolet light-driven molybdenum diselenide nanocarbon materials in heterogeneous catalysis according to claim 1 or 2, characterized in that: The reaction time of the ultraviolet light irradiation is 3 to 15 hours.

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