A method for preparing primary aromatic amines by catalytic reduction of nitroaromatic hydrocarbons by silver trifluoromethanesulfonate

Abstract

The invention discloses a method for preparing primary aromatic amines by catalytic reduction of nitroaromatics by silver trifluoromethanesulfonate, wherein the method uses cheap and readily available silver trifluoromethanesulfonate as a catalyst, phenylsilane as a hydrogen source, and a mixed solution of water and ethanol as a solvent, and does not require the use of expensive ligands. The nitroaromatics can be reduced to obtain primary aromatic amines by stirring the reaction under room temperature. The invention adopts a homogeneous silver catalytic system for the reduction of nitroaromatics, has the advantages of low cost, short reaction time, mild reaction conditions, etc., and avoids the use of special equipment such as hydrogen and autoclaves and excessive sodium borohydride reducing agents, etc.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrogenation of nitroaromatics, and particularly relates to a method for preparing primary aromatic amines with high selectivity by catalytic reduction of nitroaromatics by silver trifluoromethanesulfonate. Background Art

[0002] Amines are important starting materials and intermediates in the chemical industry and are widely used to synthesize a variety of chemical products, including various dyes, pharmaceutical products, agricultural chemicals, surfactants, polymers, resins, curing agents, etc. Therefore, developing efficient strategies to prepare amine compounds has important scientific research significance. Using nitro compounds as raw materials, direct reduction is the main way to obtain amine compounds. So far, many methods for the direct reduction of nitroaromatics to aromatic primary amines have been reported in the literature, such as catalytic hydrogenation, metal reduction, electrochemical reduction, photochemical reduction, etc.

[0003] In 2021, Wu's group started with nitroaromatics and, under hydrosilation conditions, used a well-defined N-heterocyclic carbene iron (0) complex (IMes)Fe(CO)4 as a catalyst and phenylsilane as a reducing agent to obtain the corresponding aniline derivatives with an isolated yield of 61% to 92%. This system has very good substrate applicability and is compatible with most reducing groups, and can obtain excellent yields (Adv. Synth. Catal. 2021, 363, 3859–3865).

[0004] In 2022, Behera's group reported that divalent manganese complexes were used as catalysts to efficiently catalyze the hydrosilylation of nitroaromatics to produce the corresponding aromatic amines under solvent-free conditions. This transition metal-catalyzed hydrosilylation reaction is a simple and sustainable alternative to classical hydrogenation reactions. Nitroaromatics containing different functional groups were selectively converted into the corresponding aromatic amines with good yields (Org. Lett. 2022, 24, 9179–9183).

[0005] In 2022, Han's team used B2(OH)4 as a reducing agent and added a catalyst-loaded amount of 4,4'-bipyridine to the system. It only took 5 minutes to highly selectively reduce the nitro group with excellent yield. This catalytic system is compatible with functional groups such as halogens, CN, N3, OH, COOH, and alkynyl. It is also suitable for nitroheteroaromatic hydrocarbons such as nitropyridine, quinoline, and benzimidazole, with high efficiency and good selectivity (J.Org.Chem.2022,87,910).

[0006] In 2023, Ashok Kumar's team used thiolate complexes and PhSiH3 in toluene at 60°C for 14 hours to achieve the selective reduction of aromatic nitro compounds under mild conditions. This system has very good substrate applicability and is compatible with most reducing groups, and can obtain excellent yields. In addition, this mild catalytic system can also be used for the selective reduction of aldehydes and ketones (Organometallics. 2023, 42, 732–744).

[0007] The above methods have the disadvantages of requiring chemically equivalent catalysts and precious metals, long reaction time, strict conditions and complex operations, which bring certain environmental pollution and economic cost problems, especially in large-scale industrial production processes. Therefore, developing a green and efficient strategy to prepare aromatic primary amines has important scientific research significance. Summary of the invention

[0008] The purpose of the present invention is to provide a method for preparing aromatic primary amines by highly selective reduction and hydrogenation of nitroaromatic hydrocarbons in a non-hydrogen atmosphere, using silver trifluoromethanesulfonate as a catalyst and phenylsilane as a hydrogen source.

[0009] In view of the above purpose, the technical scheme adopted by the present invention is: using silver trifluoromethanesulfonate as a catalyst, phenylsilane as a hydrogen source, and a mixed solution of water and ethanol as a solvent, stirring the nitroaromatic hydrocarbon represented by formula I at room temperature, separating and purifying the product after the reaction, and obtaining the aromatic primary amine represented by formula I′.

[0010]

[0011] In formulas I and I′, R represents any one of phenyl, naphthyl, fluorenyl, pyridyl, quinolyl, phenylboronic acid pinacol ester, 3,4-methylenedioxyphenyl, and 9,9-dimethyl substituted fluorenyl, or phenyl substituted by any one or two of hydrogen, fluorine, chlorine, bromine, trifluoromethyl, trifluoromethoxy, C1-C4 alkyl, hydroxyl, C1-C4 hydroxyalkyl, cyano, C1-C4 alkoxy, acetylamino, amino, C1-C4 alkylamino, phenyl, benzyl, benzyloxy, styryl, styryl, and ester.

[0012] In the above preparation method, it is further preferred that the amount of silver trifluoromethanesulfonate added is 1% to 10% of the molar amount of nitroaromatic hydrocarbon.

[0013] In the above preparation method, it is further preferred that the amount of phenylsilane added is 2 to 4 times the molar amount of nitroaromatic hydrocarbon.

[0014] In the above preparation method, it is further preferred to react under nitrogen atmosphere and sealed conditions at room temperature with stirring for 4 to 24 hours.

[0015] In the above preparation method, it is further preferred that the volume ratio of water to ethanol in the solvent is 1 to 3:1.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] (1) The present invention reports for the first time the use of a homogeneous silver catalytic system for the reduction of aromatic nitro compounds, thus expanding the research scope of the silver catalytic system.

[0018] (2) The present invention has mild reaction conditions, simple and green operation, and uses phenylsilane instead of H2 as a hydrogen source, avoiding the use of hydrogen and autoclave equipment, thereby improving reaction safety. The post-reaction treatment is simple, avoiding the use of acid or alkali hydrolysis, and reducing the cost of the reaction.

[0019] (3) The present invention has good substrate universality and is also compatible with some reducing functional groups such as halogens, alkenes, amides, etc., and the product yield is good. DETAILED DESCRIPTION

[0020] The present invention is further described in detail below in conjunction with the embodiments, but the protection scope of the present invention is not limited to these embodiments.

[0021] Example 1

[0022] Synthesize 1-naphthylamine with the following structural formula

[0023]

[0024] 0.0051 g (0.02 mmol) of silver trifluoromethanesulfonate and 0.0362 g (0.2 mmol) of 1-nitronaphthalene were added to a 25 mL Schlenk reaction tube, and the tube was charged and discharged three times using a double-row tube. 0.1 mL (0.8 mmol) of phenylsilane, 2.5 mL of water and a mixture of ethanol in a volume ratio of 2:1 were added in sequence under a nitrogen flow. After sealing the tube, the reaction was stirred at room temperature for 24 hours. 10 mL of saturated aqueous ammonium chloride solution was added to quench the reaction. The tube was extracted with ethyl acetate (10 mL each time, 3 times). The extracts were combined, dried with anhydrous sodium sulfate, and the product was separated by column chromatography using a mixture of petroleum ether and ethyl acetate in a volume ratio of 2:1 as a developing solvent to obtain brown solid 1-naphthylamine with a yield of 92%.

[0025] The spectral data of the obtained product are: 1 H NMR (400MHz, DMSO-d6): δ = 7.96 (d, J = 8.3Hz, 1H), 7.65-7.57 (m, 1H), 7.35-7.21 (m, 2H), 7.09(t,J=7.8Hz,1H),6.96(d,J=8.1Hz,1H),6.57(dd,J=7.5,0.9Hz,1H),5.61(s,2H);13 C NMR (100MHz, DMSO-D6): δ = 144.2, 133.7, 127.4, 126.3, 125.0, 123.2, 122.3, 121.9, 114.9, 106.9.

[0026] Comparative Example 1

[0027] 2.5 mL of the mixed solution of water and ethanol in a volume ratio of 2:1 in Example 1 was replaced with 2.5 mL of water. The other steps were the same as in Example 1. The yield of 1-naphthylamine was 60%.

[0028] Example 2

[0029] Synthesize 2-aminofluorene with the following structural formula

[0030]

[0031] In this example, 1-nitronaphthalene in Example 1 was replaced with an equal molar amount of 2-nitrofluorene, and the other steps were the same as those in Example 1 to obtain 2-aminofluorene with a yield of 86%.

[0032] The spectral data of the obtained product are: 1 H NMR (400MHz, CDCl3): δ = 7.54 (d, J = 7.6Hz, 1H), 7.46 (d, J = 8.1Hz, 1H), 7.37 (d, J = 7.4Hz, 1H), 7.22 (t, J = 7.7Hz,1H),7.14-7.04(m,1H),6.74(s,1H),6.59(dd,J=8.1,2.0Hz,1H),3.69(s,2H),3.61(s,2H); 13 C NMR (100MHz, CDCl3): δ=144.7,144.1,141.2,141.1,131.9,125.6,124.0,123.7,119.6,117.5,112.9,110.8.

[0033] Example 3

[0034] Synthesize o-aminophenol with the following structural formula

[0035]

[0036] In this example, 1-nitronaphthalene in Example 1 is replaced by an equal mole of o-nitrophenol, and the other steps are the same as those in Example 1 to obtain o-aminophenol with a yield of 85%.

[0037] The spectral data of the obtained product are: 1H NMR (400MHz, DMSO-d6): δ = 8.81 (s, 1H), 6.47 (dd, J = 7.7, 1.4Hz, 1H), 6.44-6.34 (m, 2H), 6.22 (td, J = 7.5, 1.8Hz, 1H), 4.31 (s, 2H); 13 C NMR (100MHz, DMSO-D6): δ = 143.6, 136.1, 119.1, 116.1, 114.1, 113.9.

[0038] Example 4

[0039] Synthesize p-aminophenol with the following structural formula

[0040]

[0041] In this example, 1-nitronaphthalene in Example 1 was replaced by an equal molar amount of p-nitrophenol, and the other steps were the same as those in Example 1 to obtain p-aminophenol with a yield of 82%.

[0042] The spectral data of the obtained product are: 1 H NMR (400MHz, DMSO-d6): δ = 8.24 (s, 1H), 6.37-6.18 (m, 4H), 4.24 (s, 2H); 13 C NMR (100MHz, DMSO-D6): δ = 147.8, 140.3, 115.1, 114.8.

[0043] Example 5

[0044] Synthesize 4-cyanoaniline with the following structural formula

[0045]

[0046] In this example, 1-nitronaphthalene in Example 1 was replaced by an equal mole of 4-nitrophenyl isocyanide, and the other steps were the same as those in Example 1 to obtain 4-cyanoaniline with a yield of 74%.

[0047] The spectral data of the obtained product are: 1 H NMR (400MHz, CDCl3): δ=7.42-7.38(m,2H),6.71-6.54(m,2H),4.20(s,2H); 13 C NMR (100MHz, CDCl3): δ=150.4, 133.7, 120.2, 114.4, 99.9.

[0048] Example 6

[0049] Synthesize 3,4-dimethoxyaniline with the following structural formula

[0050]

[0051] In this example, 1-nitronaphthalene in Example 1 was replaced with an equal molar amount of 3,4-dimethoxynitrobenzene, and the other steps were the same as those in Example 1 to obtain 3,4-dimethoxyaniline with a yield of 82%.

[0052] The spectral data of the obtained product are: 1 H NMR (400MHz, CDCl3): δ = 6.69 (d, J = 8.4Hz, 1H), 6.30 (d, J = 2.6Hz, 1H), 6.22 (dd, J = 8.4, 2.6Hz, 1H), 3.81 (d, J = 9.4Hz, 6H), 3.41 (s, 2H); 13 CNMR (100MHz, CDCl3): δ=149.7,142.0,140.5,112.8,106.2,100.5,56.5,55.6.

[0053] Example 7

[0054] Synthesize 4-aminoanisole with the following structural formula

[0055]

[0056] In the present embodiment, 1-nitronaphthalene in Example 1 was replaced with equimolar p-nitroanisole, and other steps were the same as in Example 1 to obtain 4-aminoanisole in a productive rate of 76%.

[0057] The spectral data of the obtained product are: 1 H NMR (400MHz, CDCl3): δ=6.77-6.73(m,2H),6.67-6.63(m,2H),3.75(s,3H),3.33(s,2H); 13 C NMR (100MHz, CDCl3): δ=152.9, 140.0, 116.6, 114.9, 55.8.

[0058] Example 8

[0059] Synthesize 4-aminophenylethanol with the following structural formula

[0060]

[0061] In this example, 1-nitronaphthalene in Example 1 was replaced by an equal molar amount of p-nitrophenylethanol, and the other steps were the same as those in Example 1 to obtain 4-aminophenylethanol with a yield of 76%.

[0062] The spectral data of the obtained product are:1 H NMR (400MHz, DMSO-d6): δ = 6.78 (d, J = 8.4Hz, 2H), 6.41 (d, J = 8.4Hz, 2H), 4.77 (s ,2H),4.49(t,J=5.2Hz,1H),3.41(t,J=7.4,5.2Hz,2H),2.45(d,J=7.7Hz,2H); 13 C NMR (100MHz, DMSO-D6): δ = 146.67, 129.28, 126.25, 113.95, 62.94, 38.49.

[0063] Example 9

[0064] Synthesize o-phenylenediamine with the following structural formula

[0065]

[0066] In this example, 1-nitronaphthalene in Example 1 is replaced by an equal molar amount of 2-nitroaniline, and the other steps are the same as those in Example 1 to obtain o-phenylenediamine with a yield of 94%.

[0067] The spectral data of the obtained product are: 1 H NMR (400MHz, CDCl3): δ = 6.77-6.70 (m, 4H), 3.41 (s, 4H); 13 C NMR (100MHz, CDCl3): δ=134.61, 120.12, 116.59.

[0068] Example 10

[0069] Synthesize p-phenylenediamine with the following structural formula

[0070]

[0071] In this example, 1-nitronaphthalene in Example 1 is replaced by an equal molar amount of 4-nitroaniline, and the other steps are the same as those in Example 1 to obtain p-phenylenediamine with a yield of 77%.

[0072] The spectral data of the obtained product are: 1 H NMR (400MHz, CDCl3): δ = 6.57 (s, 4H), 3.34 (s, 4H); 13 C NMR (100MHz, CDCl3): δ=138.78,116.92.

[0073] Embodiment 11

[0074] Synthesize 4-fluoroaniline with the following structural formula

[0075]

[0076] In this example, 1-nitronaphthalene in Example 1 was replaced by an equal molar amount of 4-fluoronitrobenzene, and the other steps were the same as those in Example 1 to obtain 4-fluoroaniline with a yield of 86%.

[0077] The spectral data of the obtained product are: 1 H NMR (400MHz, CDCl3): δ=6.89-6.82(m,2H),6.65-6.58(m,2H),3.55(s,2H); 13 C NMR (100MHz, CDCl3): δ=156.4(d,J=235.7Hz), 142.3(d,J=2.0Hz), 116.0(d,J=7.6Hz), 115.7(d,J=22.5Hz). 19 F NMR (376MHz, CDCl3): δ=-126.64.

[0078] Example 12

[0079] Synthesize 4-chloroaniline with the following structural formula

[0080]

[0081] In this example, 1-nitronaphthalene in Example 1 was replaced by an equal molar amount of 4-chloronitrobenzene, and the other steps were the same as those in Example 1 to obtain 4-chloroaniline with a yield of 88%.

[0082] The spectral data of the obtained product are: 1 H NMR (400MHz, CDCl3): δ=7.14-7.04(m,2H),6.66-6.55(m,2H),3.65(s,2H); 13 C NMR (100MHz, CDCl3): δ=144.95, 129.12, 123.13, 116.24.

[0083] Embodiment 13

[0084] Synthesize 4-bromoaniline with the following structural formula

[0085]

[0086] In this example, 1-nitronaphthalene in Example 1 was replaced by an equal molar amount of 4-bromonitrobenzene, and the other steps were the same as those in Example 1 to obtain 4-bromoaniline with a yield of 73%.

[0087] The spectral data of the obtained product are: 1H NMR (400MHz, CDCl3): δ=7.25-7.13(m,2H),6.57-6.43(m,2H),3.60(s,2H); 13 C NMR (100MHz, CDCl3): δ=145.50, 132.11, 116.82, 110.30.

[0088] Embodiment 14

[0089] Synthesize 4-trifluoromethoxyaniline with the following structural formula

[0090]

[0091] In this example, 1-nitronaphthalene in Example 1 was replaced by an equal molar amount of 4-(trifluoromethoxy)nitrobenzene, and the other steps were the same as those in Example 1 to obtain 4-trifluoromethoxyaniline with a yield of 89%.

[0092] The spectral data of the obtained product are: 1 H NMR (400MHz, CDCl3): δ=7.09-6.97(m,2H),6.76-6.53(m,2H),3.69(s,2H); 13 C NMR (100MHz, CDCl3): δ = 145.17, 141.22, 122.39, 119.34 (q, J = 253.7).115.44. 19 F NMR (376MHz, CDCl3): δ=-58.36.

[0093] Embodiment 15

[0094] Synthesize 4-aminobenzoic acid ethyl ester with the following structural formula

[0095]

[0096] In this example, 1-nitronaphthalene in Example 1 was replaced by ethyl p-nitrobenzoate in an equal mole, and the other steps were the same as in Example 1 to obtain ethyl 4-aminobenzoate with a yield of 93%.

[0097] The spectral data of the obtained product are: 1 H NMR (400MHz, CDCl3): δ=7.87-7.82(m,2H),6.64-6.59(m,2H),4.31(q,J=7.1Hz,2H),4.15(s,2H),1.35(t,J=7.1Hz,3H); 13C NMR (100MHz, CDCl3): δ=166.78, 150.90, 131.46, 119.69, 113.67, 60.27, 14.34.

[0098] Example 16

[0099] Synthesize (E)-4-phenylvinylaniline with the following structural formula

[0100]

[0101] In this example, 1-nitronaphthalene in Example 1 was replaced by an equal molar amount of (E)-1-nitro-4-phenylvinylbenzene, and the other steps were the same as those in Example 1 to obtain (E)-4-phenylvinylaniline with a yield of 85%.

[0102] The spectral data of the obtained product are: 1 H NMR (400MHz, CDCl3): δ=7.51-7.46(m,2H),7.34(td,J=6.9,1.6Hz,4H),7.25-7.19(m,1H),7.08-6.89(m,2H),6.71-6.66(m,2H),3.75(s,2H); 13 C NMR (100MHz, CDCl3): δ=146.1,137.9,128.6,127.9,127.7,126.9,126.1,125.0,115.2.

[0103] Embodiment 17

[0104] Synthesize 4-aminoacetanilide with the following structural formula

[0105]

[0106] In this example, 1-nitronaphthalene in Example 1 was replaced by an equal mole of p-nitroacetanilide, and the other steps were the same as those in Example 1 to obtain 4-aminoacetanilide with a yield of 91%.

[0107] The spectral data of the obtained product are: 1 H NMR (400MHz, DMSO-d6) δ9.50(s,1H),7.21-7.17(m,2H),6.52-6.42(m,2H),4.85(s,2H),1.95(s,3H); 13 C NMR (100MHz, DMSO-d6): δ=167.31, 144.68, 128.64, 120.89, 113.86, 23.77.

[0108] Embodiment 18

[0109] Synthesize 3-(benzyloxy)-2-methylaniline with the following structural formula

[0110]

[0111] In this example, 1-nitronaphthalene in Example 1 was replaced with an equal molar amount of 1-(benzyloxy)-2-methyl-3-nitrobenzene, and the other steps were the same as in Example 1 to obtain 3-(benzyloxy)-2-methylaniline with a yield of 94%.

[0112] The spectral data of the obtained product are: 1 H NMR (400MHz, CDCl3): δ=7.41-7.18(m,5H),6.88(t,J=8.0Hz,1H),6.29(dd,J=17.9,8.0Hz,2H),4.95(s,2H),3.52(s,2H),2.01(s,3H); 13 C NMR (100MHz, CDCl3): δ=157.5,145.9,137.9,128.7,127.9,127.4,126.7,111.1,108.8,102.7,70.3,9.4.

[0113] Embodiment 19

[0114] Synthesize 3,4-methylenedioxyaniline with the following structural formula

[0115]

[0116] In this example, 1-nitronaphthalene in Example 1 was replaced with an equal mole of 3,4-methylenedioxynitrobenzene, and the other steps were the same as those in Example 1 to obtain 3,4-methylenedioxyaniline with a yield of 77%.

[0117] The spectral data of the obtained product are: 1 H NMR (400MHz, DMSO-d6): δ = 6.52 (d, J = 8.2Hz, 1H), 6.16 (d, J = 2.2Hz, 1H), 5.94 (dd, J = 8.2, 2.2Hz, 1H), 5.74 (s, 2H), 4.69 (s, 2H); 13 C NMR (100MHz, DMSO-d6): δ=147.59, 144.12, 137.88, 108.52, 105.30, 99.90, 96.65.

[0118] Embodiment 20

[0119] Synthesize 8-aminoquinoline with the following structural formula

[0120]

[0121] In this example, 1-nitronaphthalene in Example 1 is replaced by an equal mole of 8-nitroquinoline, and the other steps are the same as those in Example 1 to obtain 8-aminoquinoline with a yield of 83%.

[0122] The spectral data of the obtained product are: 1 H NMR (400MHz, DMSO-d6): δ=8.72 (dd, J=4.1, 1.7Hz, 1H), 8.16 (dd, J=8.3, 1.7Hz, 1H), 7.44 (dd, J=8. 3,4.1Hz,1H),7.29(t,1H),7.05(dd,J=8.1,1.2Hz,1H),6.88(dd,J=7.6,1.3Hz,1H),5.94(s,1H); 13 C NMR (100MHz, DMSO-D6): δ = 147.03, 145.26, 137.45, 135.90, 128.61, 127.66, 121.50, 113.75, 108.72.

[0123] Embodiment 21

[0124] Synthesize 4-aminobiphenyl with the following structural formula

[0125]

[0126] In this example, 1-nitronaphthalene in Example 1 was replaced by an equal mole of 4-nitrobiphenyl, and the other steps were the same as those in Example 1 to obtain 4-aminobiphenyl with a yield of 96%.

[0127] The spectral data of the obtained product are: 1 H NMR (400MHz, DMSO-d6): δ=7.44(dd,J=8.2,1.0Hz,2H),7.31-7.22(m,4H),7.16-7.07(m,1H),6.59-6.53(m,2H),5.16(s,2H); 13 C NMR (100MHz, DMSO-D6): δ = 147.9, 140.2, 128.3, 126.9, 126.7, 125.2, 124.9, 113.8.

[0128] Embodiment 22

[0129] Synthesize 9,9-dimethyl-2-aminofluorene with the following structural formula

[0130]

[0131] In this example, 1-nitronaphthalene in Example 1 was replaced with an equal molar amount of 9,9-dimethyl-2-nitrofluorene, ethanol was used as the solvent, and the other steps were the same as those in Example 1 to obtain 9,9-dimethyl-2-aminofluorene with a yield of 94%.

[0132] The spectral data of the obtained product are: 1 H NMR (400MHz, CDCl3): δ = 7.49 (d, J = 7.7Hz, 1H), 7.41 (d, J = 8.0Hz, 1H), 7.27 (d, J = 7.4Hz, 1H), 7.19 (td, J = 7.4, 1.2Hz ,1H),7.12(td,J=7.4,1.5Hz,1H),6.64(d,J=2.1Hz,1H),6.55(dd,J=8.0,2.2Hz,1H),3.64(s,2H),1.35(s,6H); 13 C NMR (100MHz, CDCl3): δ=155.1,152.4,145.8,139.3,129.9,126.5,125.2,121.9,120.5,118.3,113.6,109.1,46.2,26.9.

[0133] Embodiment 23

[0134] Synthesize 4-aminophenylboronic acid pinacol ester with the following structural formula

[0135]

[0136] In this example, 1-nitronaphthalene in Example 1 was replaced with an equal mole of 4-nitrobenzeneboronic acid pinacol ester, ethanol was used as the solvent, and the other steps were the same as those in Example 1 to obtain 4-aminophenylboronic acid pinacol ester with a yield of 94%.

[0137] The spectral data of the obtained product are: 1 H NMR (400MHz, CDCl3): δ=7.83-7.25(m,2H),6.87-6.27(m,2H),3.88(s,2H),1.34(s,12H); 13 C NMR (100MHz, CDCl3): δ=149.3, 136.4, 114.0, 83.3, 24.8.

[0138] Embodiment 24

[0139] Synthesize N-methyl-p-phenylenediamine with the following structural formula

[0140]

[0141] In this example, 1-nitronaphthalene in Example 1 was replaced by an equal molar amount of N-methyl-4-nitroaniline, ethanol was used as the solvent, and the other steps were the same as those in Example 1 to obtain N-methyl-p-phenylenediamine with a yield of 92%.

[0142] The spectral data of the obtained product are: 1 H NMR (400MHz, CDCl3): δ=6.66-6.60(m,2H),6.55-6.50(m,2H),3.26(s,3H),2.79(s,3H); 13 C NMR (100MHz, CDCl3): δ=141.6, 136.6, 115.9, 113.0, 30.8.

[0143] Embodiment 25

[0144] Synthesize aniline with the following structural formula

[0145]

[0146] In this example, 1-nitronaphthalene in Example 1 is replaced by an equal molar amount of nitrobenzene, and the other steps are the same as those in Example 1 to obtain aniline with a yield of 80%.

[0147] The spectral data of the obtained product are: 1 H NMR (400MHz, DMSO-d6): δ = 6.86-6.78 (m, 2H), 6.45-6.37 (m, 2H), 6.32 (t, J = 7.5Hz, 1H), 4.81 (s, 2H); 13 C NMR (100MHz, DMSO-D6): δ = 148.1, 128.4, 115.3, 113.5.

Claims

1. A method for preparing primary aromatic amines by catalytic reduction of nitroaromatic hydrocarbons using silver trifluoromethanesulfonate, characterized in that: Using silver trifluoromethanesulfonate as a catalyst, phenylsilane as a hydrogen source, and a mixture of water and ethanol as a solvent, the nitroaromatic hydrocarbon represented by formula I is stirred and reacted at room temperature, and the product is separated and purified after the reaction to obtain the aromatic primary amine represented by formula I′; In formulas I and I′, R represents any one of phenyl, naphthyl, fluorenyl, pyridyl, quinolyl, phenylboronic acid pinacol ester, 3,4-methylenedioxyphenyl, and 9,9-dimethyl substituted fluorenyl, or any one or two of fluorine, chlorine, bromine, trifluoromethyl, trifluoromethoxy, C1-C4 alkyl, hydroxyl, C1-C4 hydroxyalkyl, cyano, C1-C4 alkoxy, acetylamino, amino, C1-C4 alkylamino, phenyl, benzyl, benzyloxy, styryl, and phenylpropenyl substituted.

2. The method for preparing primary aromatic amines by catalytic reduction of nitroaromatic hydrocarbons by silver trifluoromethanesulfonate according to claim 1, characterized in that: The amount of silver trifluoromethanesulfonate added is 1% to 10% of the molar amount of the nitroaromatic hydrocarbon.

3. The method for preparing primary aromatic amines by catalytic reduction of nitroaromatic hydrocarbons by silver trifluoromethanesulfonate according to claim 1, characterized in that: The amount of phenylsilane added is 2 to 4 times the molar amount of nitroaromatic hydrocarbon.

4. The method for preparing primary aromatic amines by catalytic reduction of nitroaromatic hydrocarbons by silver trifluoromethanesulfonate according to claim 1, characterized in that: The reaction was stirred at room temperature under nitrogen atmosphere and sealed conditions for 4 to 24 hours.

5. The method for preparing primary aromatic amines by catalytic reduction of nitroaromatic hydrocarbons by silver trifluoromethanesulfonate according to claim 1, wherein the volume ratio of water to ethanol in the solvent is 1 to 3:1.

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