Method for selectively hydrogenating polycyclic aromatic hydrocarbon under electrochemical condition and application thereof

Abstract

The invention discloses a method for selectively hydrogenating polycyclic aromatic hydrocarbon under an electrochemical condition and application of the method, and belongs to the technical field of electrolysis processes for producing compounds. According to the method for selectively hydrogenating the polycyclic aromatic hydrocarbon under the electrochemical condition, preparation of alkenyl-substituted aromatic hydrocarbon or alkyl-substituted aromatic hydrocarbon is realized with high selectivity under current driving, and the method has the advantages that raw materials are cheap and easy to obtain, green and environment-friendly, and reaction conditions are safe and mild, and has good application potential in modification and synthesis of medicines and chemical raw materials.

Description

Technical Field

[0001] The invention relates to the technical field of electrolytic process for producing compounds, and in particular to a method for selective hydrogenation of polycyclic aromatic hydrocarbons under electrochemical conditions and application thereof. Background Art

[0002] Aromatic hydrocarbons are widely present in nature. The reduction products and derivatives of aromatic hydrocarbons are a very important class of compounds. Their skeletons are widely present in many natural products and drugs with biological activity. The preparation of their corresponding reduction products by reduction of aromatic hydrocarbons is a direct and step-economical method.

[0003] Using aromatic hydrocarbons as substrates, the preparation of corresponding alkenes and alkanes often requires two completely different reaction conditions.

[0004] The first is the Birch reduction to obtain olefin products, which was first published by Australian chemist Birch ([1]. J. Chem. Soc. 1944, 430; [2.] Nature 1946, 158, 60.). The Birch reduction product requires a single-electron reducing agent, such as highly active metallic lithium or metallic sodium, and the reaction is prepared in low-temperature liquid ammonia. In recent years, a series of other single-electron reducing agents have also been developed in the research literature of scholars in this field ([1]. J. Am. Chem. Soc. 2005, 127, 9338; [2]. Nat. Protoc. 2007, 2, 1888; [3]. Tetrahedron Lett. 2009, 50, 5463-5466), but all require an equivalent to an excess amount of chemical reducing agent.

[0005] The second method is the catalytic hydrogenation method for preparing alkanes, which uses transition metal catalysts such as palladium, rhodium, ruthenium, iridium, and nickel to react with high-pressure hydrogen under high temperature conditions. Recent research literature ([1]. Nat. Commun. 2016, 7, 11326; [2]. ACS. Catal. 2020, 10, 11365; [3]. Org. Lett. 2021, 23, 1910) has also proposed and developed relatively mild reaction conditions. In 2019, a method for selective hydrogenation of polycyclic aromatic hydrocarbons catalyzed by inexpensive metals (J. Am. Chem. Soc. 2019, 141, 9018) was reported. The use of cobalt and chromium can achieve different degrees of hydrogenation of polycyclic aromatic hydrocarbons and synthesize alkyl-substituted aromatic hydrocarbons.

[0006] Although the above hydrogenation method is widely used, the alkali metals, liquid ammonia and high-pressure hydrogen used in the reaction are highly dangerous, the metal catalyst is expensive, the reaction conditions are relatively harsh, and the compatibility with functional groups is poor. There is still a large gap and challenges in achieving safe, green and large-scale industrial production.

[0007] Therefore, proposing a simple, green and widely applicable selective hydrogenation pathway for aromatics can reduce production costs and the difficulty of expanding production, which is of great significance to the chemical, pharmaceutical and other fields. Summary of the invention

[0008] In view of the above-mentioned defects of the prior art, in a first aspect of the present invention, a simple, green, well-applicable and low-cost method for selective hydrogenation of polycyclic aromatic hydrocarbons under electrochemical conditions is provided, comprising the following steps: In an inert atmosphere, polycyclic aromatic hydrocarbon compounds are mixed with an organic amine additive, an electrolyte, and an organic solvent to obtain an electrolyte; the electrolyte is electrolyzed under the action of direct current to complete selective hydrogenation, and hydrogenated aromatic hydrocarbons are obtained after separation and purification; The polycyclic aromatic hydrocarbon compounds include polycyclic aromatic hydrocarbons having 2-5 aromatic rings and their substitutes; the organic solvent includes an olefin-forming organic solvent or an alkane-forming organic solvent; the hydrogenated aromatic hydrocarbons include an olefin-substituted aromatic hydrocarbon or an alkyl-substituted aromatic hydrocarbon; in the preparation process of the electrolyte, the olefin-forming organic solvent or the alkane-forming organic solvent is selected according to the product form of the target olefin-substituted aromatic hydrocarbon or alkyl-substituted aromatic hydrocarbon; The olefin-forming organic solvent includes at least one of tetrahydrofuran, dioxane, and acetonitrile; the alkane-forming organic solvent includes N, N -dimethylformamide, N,N - At least one of dimethylacetamide and dimethyl sulfoxide.

[0009] Based on the above technical scheme, the inventive concept of the present invention is to achieve the purpose of selective hydrogenation by selecting different types of organic solvents. The selectivity of organic solvents for the reaction originates from the electrochemical properties of different solvents, that is, it is achieved by affecting the rate of generation and migration of anode protons during the electrolysis process. The diffusion rate of protons released by the anode in olefin-forming organic solvents is slow, and only the process of electrochemical reduction of aromatic hydrocarbons exists in the reaction; in alkane-forming organic solvents, the proton diffusion rate is fast, hydrogen ions can be further reduced to hydrogen radicals, and hydrogen radicals can further reduce olefins to alkane products. There are two processes in the reaction: electrochemical reduction and hydrogen radical reduction. Therefore, by controlling the type of organic solvent, the electrolysis process can be adjusted, and the path of selective hydrogenation of polycyclic aromatic hydrocarbons can be adjusted in a simple way.

[0010] Preferably, the polycyclic aromatic hydrocarbons include one of naphthalene, anthracene, perylene, carbazole, benzofuran, dibenzofuran, dibenzothiophene, biphenyl, and quinoline; in the substituents of the polycyclic aromatic hydrocarbons, the substituents include at least one of phenyl, hydroxyl, dimethylamino, cyclohex-3-ene-1-carboxamide, fluorine, cyano, methoxy, and ethyl 1-methylacetate.

[0011] Further preferably, the polycyclic aromatic hydrocarbon compounds include naphthalene, N -phenylcarbazole, perylene, dibenzofuran, dibenzothiophene, benzofuran, 1-naphthol, N,N - one of dimethyl-1-naphthylamine, cyclohex-3-ene-1-carboxamidonaphthalene, 1-fluoronaphthalene, 2-naphthalenenitrile, naproxen ethyl ester, terphenyl, 2-phenylquinoline, and 1,6-dimethoxynaphthalene.

[0012] Preferably, the organic amine additive includes triethylamine, trimethylamine, tri-n-butylamine, N,N - at least one of diisopropylethylamine, dibenzylamine and diethylamine.

[0013] When the electrolysis is powered on, the organic amine additive will be oxidized at the anode, releasing hydrogen ions in situ and providing a hydrogen source for the hydrogenation reaction, while also providing electrons for the cathode reduction reaction.

[0014] The changes of organic amine additives during electrolysis are as follows: ; In the formula, R only represents the concept of functional groups or atoms in the organic amine additive, and the types thereof may be the same or different, depending on the specific type of the organic amine additive (for example, when triethylamine is used, R is an ethyl group; when dibenzylamine is used, R includes a benzyl group and a hydrogen atom).

[0015] Electrolytes play a role in improving the conductivity of the system during electrolysis and are a common form of additive added in the field. Electrolytes are chemically inert relative to reaction substrates and products, and there are many types of electrolytes to choose from. Those skilled in the art can select the appropriate type of electrolyte based on actual conditions.

[0016] Preferably, the electrolyte includes at least one of tetra-n-butylammonium hexafluorophosphate, tetra-n-butylammonium bromide, tetra-n-butylammonium tetrafluoroborate, tetraethylammonium chloride, lithium bromide, and lithium perchlorate.

[0017] Controlling the raw material ratio within a suitable range is crucial for optimizing electrolysis efficiency and product quality. A suitable raw material ratio can increase the reaction rate, avoid waste of raw materials, and reduce energy consumption while increasing industrial production capacity. Those skilled in the art can select a suitable amount of organic solvent according to the actual amount of raw materials and the electrolysis production method, without special limitations. For example, in an ordinary electrolytic cell, an organic solvent is added and the polycyclic aromatic hydrocarbons are controlled to be 0.05-0.1 mol / L; in an industrial flow electrolysis process, a larger amount of organic solvent can be added according to actual conditions, which can also achieve the purpose of the present invention.

[0018] Preferably, the molar ratio of the polycyclic aromatic hydrocarbon compound, the electrolyte, and the organic amine additive is 1:(0.2-2):(1-12) respectively.

[0019] The present invention can complete the selective hydrogenation of polycyclic aromatic hydrocarbons with high current efficiency and low current density, which is conducive to reducing energy consumption. In addition, the electrolysis can be carried out at a wide range of temperatures without the need for extremely high or low temperatures and high pressure reaction environments. For the purpose of taking into account both the product yield and the electrolysis energy consumption, the electrolysis time is suitably controlled within a suitable range. As presented in one or more embodiments of the present invention, the above effect can be achieved by electrolyzing for 3-12 h.

[0020] Preferably, the current density of the electrolysis is 2-100 mA / cm 2 ; The ambient temperature for electrolysis is 0-50 ℃; The duration of electrolysis is 3-12 h.

[0021] Preferably, in the electrodes for electrolysis, the anode includes one of a carbon electrode or a platinum electrode; and the cathode includes one of a carbon electrode or a lead electrode.

[0022] In the second aspect of the present invention, there is provided an application of the method for selective hydrogenation of polycyclic aromatic hydrocarbons under electrochemical conditions according to the first aspect of the present invention, which is used for the synthesis of chemical raw materials and drugs.

[0023] Preferably, the method for selective hydrogenation of polycyclic aromatic hydrocarbons under electrochemical conditions is used to synthesize the pharmaceutical intermediate 5-methoxy-2-tetralone for the preparation of the drug rotigotine.

[0024] The present invention does not require specialized production equipment and specific container surface treatment, and can be implemented using a common electrolysis device in the field, and has good applicability in industrial production. Those skilled in the art can use an electrolytic cell or flow electrochemistry to complete the selective hydrogenation, and it is easy to scale up the production. After the electrolysis is completed, the product is easy to separate and purify, and the target product can be obtained simply and quickly by conventional methods, such as extraction.

[0025] Compared with the prior art, the present invention has the following advantages and beneficial effects: The present invention provides a method for selective hydrogenation of polycyclic aromatic hydrocarbons under electrochemical conditions, which realizes the preparation of alkenyl-substituted aromatic hydrocarbons or alkyl-substituted aromatic hydrocarbons with high selectivity under current drive, and has the advantages of cheap and readily available raw materials, green environmental protection, and safe and mild reaction conditions.

[0026] The present invention provides an application of a method for selective hydrogenation of polycyclic aromatic hydrocarbons under electrochemical conditions, which has good application potential in the modification and synthesis of drugs and chemical raw materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the reaction principle of polycyclic aromatic hydrocarbons at the cathode during electrolysis. DETAILED DESCRIPTION

[0028] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The experimental methods in the following examples without specifying specific conditions are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0029] Example 1 The method for selective hydrogenation of polycyclic aromatic hydrocarbons under electrochemical conditions comprises the following steps:

[0030] In the electrolytic cell, a platinum electrode (1.5 cm×2 cm×0.03 cm) was fixed as the anode and a carbon electrode (1.5 cm×2 cm×0.3 cm) was fixed as the cathode. Under an inert atmosphere, 0.3 mmol naphthalene and 0.3 mmol tetrabutylammonium tetrafluoroborate ( n Bu 4 NBF 4 ), 0.8 mmol triethylamine (Et 3 N), 6 mL tetrahydrofuran (THF), electrolyzed at 10 mA for 3 h at room temperature with good stirring; the reaction was stopped, ethyl acetate and water were added for extraction, washed with saturated sodium chloride solution, dried, and the solvent was evaporated to obtain 1,4-dihydronaphthalene with a yield of 72%.

[0031] The NMR spectrum data of the product are as follows: 1 H NMR (400 MHz, CDCl 3 ) δ 7.06-7.07 (m, 4H), 5.92 (t, J = 1.2 Hz, 2H),3.39 (d, J = 1.2 Hz, 4H). 13C NMR (101 MHz, CDCl 3 ) δ 134.34, 128.55, 126.02, 124.90, 77.48,77.16, 76.84, 29.88, 29.86. The above data results show that the target product was synthesized.

[0032] Example 2 The method for selective hydrogenation of polycyclic aromatic hydrocarbons under electrochemical conditions comprises the following steps:

[0033] In the electrolytic cell, a platinum electrode (1.5 cm × 2 cm × 0.03 cm) was fixed as the anode and a carbon electrode (1.5 cm × 2 cm × 0.3 cm) was fixed as the cathode. Under an inert atmosphere, 0.3 mmol naphthalene, 0.3 mmol tetrabutylammonium tetrafluoroborate, 1.5 mmol triethylamine, and 6 mL N,N -Dimethylformamide ( N,N -Dimethylformamide, DMF), under well-stirred room temperature conditions, electrolyzed at 10 mA current for 5 h; the reaction was stopped, ethyl acetate and water were added for extraction, washed with saturated sodium chloride solution, dried, and the solvent was evaporated to obtain 1,2,3,4-tetrahydronaphthalene with a yield of 75%.

[0034] The NMR spectrum data of the product are as follows: 1 H NMR (400 MHz, CDCl 3 ) δ 7.08-7.06 (m, 4H), 2.78-2.75 (m, 4H), 1.81-1.78 (m, 4H). 13 C NMR (101 MHz, CDCl 3 ) δ 137.23, 129.26, 125.52, 125.50, 29.50,29.49, 23.33, 23.31. The above data results show that the target product was synthesized.

[0035] Example 3 The method for selective hydrogenation of polycyclic aromatic hydrocarbons under electrochemical conditions comprises the following steps:

[0036] In the electrolytic cell, fixed carbon electrodes (1.5 cm × 2 cm × 0.3 cm) were used as anode and cathode. Under inert atmosphere, 0.5 mmol N-phenylcarbazole, 0.3 mmol lithium bromide (LiBr), 1.0 mmol tri-n-butylamine (Bu 3 N), 6 mL tetrahydrofuran, electrolyzed at 30 mA current for 3 h under well-stirred room temperature conditions; stopped the reaction, added ethyl acetate and water for extraction, washed with saturated sodium chloride solution, dried, and evaporated the solvent to obtain N -Dihydrogen product of phenylcarbazole, yield 80%.

[0037] The NMR spectrum data of the product are as follows: 1 H NMR (400 MHz, CDCl 3 ) δ 7.55-7.49 (m, 3H), 7.40-7.35 (m, 3H), 7.24-7.21 (m, 1H), 7.15-7.12 (m, 2H), 6.07-6.04 (m, 1H), 5.91-5.88 (m, 1H), 3.53-3.50 (m, 2H), 3.31-3.28 (m, 2H). 13 C NMR (101 MHz, CDCl 3 ) δ 137.93, 137.54, 132.93, 129.46, 127.44,127.34, 127.18, 125.32, 122.81, 121.61, 119.73, 118.00, 109.91, 108.07,24.50, 23.61. HRMS (ESI) ([M + H] + ) calculated for C 18 H 16 N: 246.1277, found:246.1277. The above data results show that the target product was synthesized.

[0038] Example 4 The method for selective hydrogenation of polycyclic aromatic hydrocarbons under electrochemical conditions comprises the following steps:

[0039] In the electrolytic cell, fixed carbon electrodes (1.5 cm × 2 cm × 0.3 cm) were used as anode and cathode. Under inert atmosphere, 0.5 mmol N -phenylcarbazole, 0.3 mmol tetrabutylammonium tetrafluoroborate, 2.5 mmol tri-n-butylamine, 6 mL N,N-dimethylformamide, under well-stirred room temperature conditions, electrolyzed at 30 mA current for 5 h; stopped the reaction, added ethyl acetate and water for extraction, washed with saturated sodium chloride solution, dried, and evaporated the solvent to obtain N -The tetrahydro product of phenylcarbazole was obtained in 70% yield.

[0040] The NMR spectrum data of the product are as follows: 1 H NMR (400 MHz, CDCl 3 ) δ 7.52-7.48 (m, 3H), 7.38-7.35 (m, 3H), 7.24-7.22 (m, 1H), 7.13-7.10 (m, 2H), 2.81-2.79 (m, 2H), 2.62-2.59 (m, 2H), 1.90-1.89 (m, 4H). 13 C NMR (101 MHz, CDCl 3 ) δ 138.07, 137.19, 135.96, 129.43, 127.77,127.30, 127.09, 121.37, 119.67, 117.85, 111.02, 109.95, 23.50, 23.36, 23.25,21.22. The above data results show that the target product was synthesized.

[0041] Example 5 The method for selective hydrogenation of polycyclic aromatic hydrocarbons under electrochemical conditions comprises the following steps:

[0042] In the electrolytic cell, fixed carbon electrodes (1.5 cm×2 cm×0.3 cm) were used as anode and cathode. Under an inert atmosphere, 0.3 mmol perylene, 0.3 mmol tetrabutylammonium tetrafluoroborate, 3.0 mmol triethylamine, and 6 mL tetrahydrofuran were added. Under well-stirred conditions at 40 °C, electrolysis was carried out at a current of 50 mA for 3 h. The reaction was stopped, ethyl acetate and water were added for extraction, washed with saturated sodium chloride solution, dried, and the solvent was evaporated to obtain the octahydro product of perylene with a yield of 50%.

[0043] The NMR spectrum data of the product are as follows: 1 H NMR (400 MHz, CDCl 3) δ 7.25-7.22 (m, 2H), 7.16-7.12 (m, 2H), 7.01-6.99 (m, 2H), 3.57-3.53 (m, 2H), 2.87-2.83 (m, 4H), 2.72-2.69 (m, 2H), 2.21-2.16 (m, 2H), 2.01-1.91 (m, 4H). 13 C NMR (101 MHz, CDCl 3 ) δ 141.48, 136.76, 135.82, 126.74, 125.57,121.28, 37.92, 30.21, 27.47, 22.72. The above data results show that the target product was synthesized.

[0044] Example 6 The method for selective hydrogenation of polycyclic aromatic hydrocarbons under electrochemical conditions comprises the following steps:

[0045] In the electrolytic cell, fixed carbon electrodes (1.5 cm × 2 cm × 0.3 cm) were used as anode and cathode. Under an inert atmosphere, 0.3 mmol of dibenzofuran and 0.3 mmol of lithium perchlorate (LiClO) were added. 4 ), 1.0 mmol tri-n-butylamine, 5 mL 1,4-dioxane and 1 mL acetonitrile (MeCN), under well-stirred room temperature conditions, electrolyzed at 10 mA current for 3 h; stopped the reaction, added ethyl acetate and water for extraction, washed with saturated sodium chloride solution, dried, and evaporated the solvent to obtain 1,4-dihydrodibenzofuran with a yield of 73%.

[0046] The NMR spectrum data of the product are as follows: 1 H NMR (400 MHz, CDCl 3 ) δ 7.44-7.41 (m, 2H), 7.23-7.20 (m, 2H), 5.98-5.89 (m, 2H), 3.43-3.35 (m, 4H). 13 C NMR (101 MHz, CDCl 3 ) δ 154.45, 151.26, 128.17, 124.82, 123.41,122.88, 122.41, 118.68, 111.00, 110.35, 25.06, 23.67. The above data results show that the target product was synthesized.

[0047] Example 7 The method for selective hydrogenation of polycyclic aromatic hydrocarbons under electrochemical conditions comprises the following steps:

[0048] In the electrolytic cell, a fixed carbon electrode (1.5 cm × 2 cm × 0.3 cm) was used as the anode and a lead electrode (1.5 cm × 2 cm × 0.05 cm) was used as the cathode. Under an inert atmosphere, 0.3 mmol of dibenzothiophene, 0.3 mmol of tetra-n-butylammonium tetrafluoroborate, 1.5 mmol of tri-n-butylamine, and 6 mL of N,N -dimethylformamide, under well-stirred room temperature conditions, electrolyzed at 10 mA current for 5 h; the reaction was stopped, ethyl acetate and water were added for extraction, washed with saturated sodium chloride solution, dried, and the solvent was evaporated to obtain 1,2,3,4-tetrahydrodibenzothiophene with a yield of 64%.

[0049] The NMR spectrum data of the product are as follows: 1 H NMR (400 MHz, CDCl 3 ) δ 7.76 -7.74 (m, 1H), 7.57-7.55 (m, 1H), 7.34-7.30 (m, 1H), 7.27-7.23 (m, 1H), 2.86-2.83 (m, 2H), 2.76-2.72 (m, 2H), 1.93-1.91 (m, 4H). 13 C NMR (101 MHz, CDCl 3 ) δ 139.88, 138.47, 137.14, 129.58, 123.89,123.64, 122.35, 120.53, 25.79, 23.77, 23.73, 22.44. The above data results show that the target product was synthesized.

[0050] Example 8 The method for selective hydrogenation of polycyclic aromatic hydrocarbons under electrochemical conditions comprises the following steps:

[0051] In the electrolytic cell, fixed carbon electrodes (1.5 cm × 2 cm × 0.3 cm) were used as anode and cathode. Under an inert atmosphere, 1.5 mmol benzofuran and 0.3 mmol tetra-n-butylammonium bromide ( nBu 4 NBr), 2 mmol diethylamine (Et 2 NH), 6 mL N, N -Dimethylformamide was electrolyzed at 30 mA for 6 h at room temperature with good stirring; the reaction was stopped, ethyl acetate and water were added for extraction, washed with saturated sodium chloride solution, dried, and the solvent was evaporated to obtain 2,3-dihydrobenzofuran in a yield of 68%.

[0052] The NMR spectrum data of the product are as follows: 1 H NMR (400 MHz, CDCl 3 ) δ 7.19 (d, J = 6.4 Hz, 1H), 7.08-7.13 (m, 1H), 6.81-6.86 (m, 2H), 6.79 (d, J = 8.0 Hz, 1H), 4.56 (t, J = 8.8 Hz, 2H), 3.21 (t, J =8.8 Hz, 2H); 13 C NMR (101 MHz, CDCl 3 ) δ = 161.17, 127.87, 27.76, 124.90, 120.35,109.33, 71.01, 29.80. The above data results show that the target product was synthesized.

[0053] Example 9 The method for selective hydrogenation of polycyclic aromatic hydrocarbons under electrochemical conditions comprises the following steps:

[0054] In the electrolytic cell, a platinum electrode (1.5 cm × 2 cm × 0.03 cm) was fixed as the anode and a carbon electrode (1.5 cm × 2 cm × 0.3 cm) was fixed as the cathode. Under an inert atmosphere, 0.5 mmol 1-naphthol and 0.3 mmol tetraethylammonium chloride (Et 4 NCl), 1.0 mmol dibenzylamine (Bn 2 NH), 5 mL tetrahydrofuran and 1 mL acetonitrile, under well-stirred room temperature conditions, electrolyzed at 10 mA for 4 h; the reaction was stopped, ethyl acetate and water were added for extraction, washed with saturated sodium chloride solution, dried, and the solvent was evaporated to obtain 5,8-dihydro-1-naphthol with a yield of 73%.

[0055] The NMR spectrum data of the product are as follows: 1 H NMR (400 MHz, CDCl 3 ) δ 7.05-7.01 (m, 1H), 6.73-6.71 (m, 1H), 6.63-6.61 (m, 1H), 5.94-5.87 (m, 2H), 4.71 (s, 1H), 3.40-3.38 (m, 2H), 3.29-3.27(m, 2H). 13 C NMR (101 MHz, CDCl 3 ) δ 153.09, 135.87, 126.64, 124.51, 123.76,121.04, 112.12, 29.54, 23.97. The above data results show that the target product was synthesized.

[0056] Example 10 The method for selective hydrogenation of polycyclic aromatic hydrocarbons under electrochemical conditions comprises the following steps:

[0057] In the electrolytic cell, a platinum electrode (1.5 cm × 2 cm × 0.03 cm) was fixed as the anode and a carbon electrode (1.5 cm × 2 cm × 0.3 cm) was fixed as the cathode. Under an inert atmosphere, 0.3 mmol N,N -dimethyl-1-naphthylamine, 0.3 mmol tetra-n-butylammonium hexafluorophosphate ( n Bu 4 NPF 6 ), 1.5 mmol triethylamine, 6 mL dimethyl sulfoxide (DMSO), under stirring at room temperature, electrolyze at 10 mA current for 5 h; stop the reaction, add ethyl acetate and water to extract, wash with saturated sodium chloride solution, dry, and evaporate the solvent to obtain N,N -dimethyl-5,6,7,8-tetrahydro-1-naphthylamine, the yield was 45%.

[0058] The NMR spectrum data of the product are as follows: 1 H NMR (400 MHz, CDCl 3 ) δ 7.09 (t, J = 8.0 Hz, 1H), 6.90 (d, J = 8.0 Hz,1H), 6.81(d, J= 7.6 Hz, 1H), 2.80 (t, J = 6.0 Hz, 2H), 2.73(t, J = 6.0 Hz, 2H), 2.67 (s, 6H), 1.78-1.76 (m, 4H). 13 C NMR (101 MHz, CDCl 3 ) δ 152.67, 138.31, 132.30, 125.78, 124.17,115.80, 44.62, 29.82, 25.62, 23.33, 23.16. The above data results show that the target product was synthesized.

[0059] Embodiment 11 The method for selective hydrogenation of polycyclic aromatic hydrocarbons under electrochemical conditions comprises the following steps:

[0060] In the electrolytic cell, a platinum electrode (1.5 cm×2 cm×0.03 cm) was fixed as the anode and a carbon electrode (1.5 cm×2 cm×0.3 cm) was fixed as the cathode. Under an inert atmosphere, 0.5 mmol of cyclohex-3-ene-1-carboxamidonaphthalene, 0.3 mmol of tetra-n-butylammonium hexafluorophosphate, and 1.5 mmol of N,N -Diisopropylethylamine ( N,N -Diisopropylethylamine, DIPEA), 5 mL tetrahydrofuran and 1 mL acetonitrile were electrolyzed at 20 mA for 3 hours under well-stirred room temperature conditions. The reaction was stopped, ethyl acetate and water were added for extraction, and the product was washed with saturated sodium chloride solution, dried, and the solvent was evaporated to obtain the enamide naphthalene dihydrogen product with a yield of 59%.

[0061] The NMR spectrum data of the product are as follows: 1 H NMR (400 MHz, CDCl 3 ) δ 7.66 (d, J = 8.0 Hz, 1H) 7.16 (d, J = 8.0 Hz,1H), 7.10 (s, 1H), 6.95 (d, J= 8.0 Hz, 1H), 5.93-5.84 (m, 2H), 5.76 (s, 2H), 3.42-3.41 (m, 2H), 3.21-3.19 (m, 2H), 2.58-2.55 (m, 1H), 2.39-2.33 (m, 2H),2.20-2.15 (m, 2H), 2.06-2.02 (m, 1H), 1.87-1.82 (m, 1H). 13 C NMR (101 MHz, CDCl 3 ) δ 174.13, 135.01, 134.89, 127.32, 126.54,125.68, 125.35, 124.88, 122.99, 121.26, 42.19, 29.89, 28.32, 25.91, 25.59,24.59. HRMS (ESI) ([M + H] + ) calculated for C 17 H 20 NO: 254.1539, found:254.1537. The above data results show that the target product was synthesized.

[0062] Example 12 The method for selective hydrogenation of polycyclic aromatic hydrocarbons under electrochemical conditions comprises the following steps:

[0063] In the electrolytic cell, a platinum electrode (1.5 cm×2 cm×0.03 cm) was fixed as the anode and a carbon electrode (1.5 cm×2 cm×0.3 cm) was fixed as the cathode. Under an inert atmosphere, 0.5 mmol 1-fluoronaphthalene, 0.3 mmol tetra-n-butylammonium tetrafluoroborate, and 1.5 mmol N,N -Diisopropylethylamine, 4 mL tetrahydrofuran and 2 mL acetonitrile were electrolyzed at 15 mA for 5 h at room temperature with good stirring; the reaction was stopped, ethyl acetate and water were added for extraction, washed with saturated sodium chloride solution, dried, and the solvent was evaporated to obtain 5,8-dihydro-1-fluoronaphthalene with a yield of 75%.

[0064] The NMR spectrum data of the product are as follows: 1 H NMR (400 MHz, CDCl 3) δ 7.13-7.07 (m, 1H), 6.90-6.83 (m, 2H), 5.90-5.89 (m, 2H), 3.40-3.38 (m, 2H), 3.35-3.33 (m, 2H). 19 F NMR (377 MHz, CDCl 3 ) δ -118.65. The above data results show that the target product was synthesized.

[0065] Example 13 The method for selective hydrogenation of polycyclic aromatic hydrocarbons under electrochemical conditions comprises the following steps:

[0066] In the electrolytic cell, a platinum electrode (1.5 cm×2 cm×0.03 cm) was fixed as the anode and a carbon electrode (1.5 cm×2 cm×0.3 cm) was fixed as the cathode. Under an inert atmosphere, 0.5 mmol 2-naphthonitrile, 0.3 mmol tetra-n-butylammonium hexafluorophosphate, and 1.5 mmol N,N -Diisopropylethylamine, 5 mL tetrahydrofuran and 1 mL acetonitrile were electrolyzed at 5 mA for 3 h at 0 °C with good stirring; the reaction was stopped, ethyl acetate and water were added for extraction, washed with saturated sodium chloride solution, dried, and the solvent was evaporated to obtain 1,4-dihydronaphthalene-2-carbonitrile with a yield of 60%.

[0067] The NMR spectrum data of the product are as follows: 1 H NMR (400 MHz, CDCl 3 ) δ 7.25-7.20 (m, 2H), 7.17-7.11 (m, 2H), 6.83-6.83 (m, 1H), 3.58 (s, 3H). 13 C NMR (101 MHz, CDCl 3 ) δ 142.37, 131.96, 131.49, 128.50, 126.98,119.11, 110.59, 31.27, 30.73. HRMS (ESI) ([M + H] + ) calculated for C 11 H 10 N: 156.0808, found:156.0809. The above data results show that the target product was synthesized.

[0068] Embodiment 14 The method for selective hydrogenation of polycyclic aromatic hydrocarbons under electrochemical conditions comprises the following steps:

[0069] In the electrolytic cell, a platinum electrode (1.5 cm×2 cm×0.03 cm) was fixed as the anode and a carbon electrode (1.5 cm×2cm×0.3 cm) was used as the cathode. Under an inert atmosphere, 0.3 mmol of naproxen ethyl ester, 0.3 mmol of tetra-n-butylammonium hexafluorophosphate, 1.5 mmol of tri-n-butylamine, 5 mL of tetrahydrofuran and 1 mL of acetonitrile were added. The electrolysis was carried out at 20 mA for 3 h at room temperature with good stirring. The reaction was stopped, ethyl acetate and water were added for extraction, washed with saturated sodium chloride solution, dried, and the solvent was evaporated to obtain the dihydro product of naproxen ethyl ester with a yield of 68%.

[0070] The NMR spectrum data of the product are as follows: 1 H NMR (400 MHz, CDCl 3 ) δ 7.14 (s, 3H), 4.86-4.84 (1H), 4.23-4.10 (m,2H), 3.70 (t, J = 7.2 Hz, 1H), 3.65 (s, 3H), 3.55-3.51 (m, 2H), 3.45-3.43 (m, 2H), 1.53-1.51 (m, 3H), 1.30-1.23 (2m, 3H). 13 C NMR (101 MHz, CDCl 3 ) δ 174.83, 153.36, 138.45, 134.59, 132.62,128.67, 127.04, 125.09, 90.63, 60.81, 54.26, 45.29, 31.96, 29.58, 18.83,14.25. HRMS (ESI) ([M + H] + ) calculated for C 16 H 21 O 3 : 261.1485, found:261.1485. The above data results show that the target product was synthesized.

[0071] Embodiment 15 The method for selective hydrogenation of polycyclic aromatic hydrocarbons under electrochemical conditions comprises the following steps:

[0072] In the electrolytic cell, fixed carbon electrodes (1.5 cm × 2 cm × 0.3 cm) were used as anode and cathode. Under an inert atmosphere, 0.5 mmol terphenyl, 0.5 mmol tetra-n-butylammonium hexafluorophosphate, and 6.0 mmol N,N -Diisopropylethylamine, 6 mL N,N -dimethylformamide, under well-stirred conditions at 50 °C, electrolyzed at 30 mA for 12 h; the reaction was stopped, ethyl acetate and water were added for extraction, washed with saturated sodium chloride solution, dried, and the solvent was evaporated to obtain 1,4-dicyclohexylbenzene with a yield of 65%.

[0073] The NMR spectrum data of the product are as follows: 1 H NMR (400 MHz, CDCl 3 ) δ 7.13 (s, 4H), 2.49-2.43 (m, 2H), 1.86-1.82(m, 8H), 1.75-1.72 (m, 2H), 1.45-1.32 (m, 8H), 1.27-1.22 (m, 2H). 13 C NMR (101 MHz, CDCl 3 ) δ 145.53, 126.73, 44.17, 34.59, 27.03, 26.27. The above data results show that the target product was synthesized.

[0074] Example 16 The method for selective hydrogenation of polycyclic aromatic hydrocarbons under electrochemical conditions comprises the following steps:

[0075] In the electrolytic cell, a platinum electrode (1.5 cm×2 cm×0.03 cm) was fixed as the anode and a carbon electrode (1.5 cm×2 cm×0.3 cm) was fixed as the cathode. Under an inert atmosphere, 1.0 mmol 2-phenylquinoline, 0.5 mmol tetra-n-butylammonium hexafluorophosphate, and 2.5 mmol N,N -Diisopropylethylamine, 10 mL N,N -Dimethylacetamide ( N,N-Dimethylacetamide, DMAc), under well-stirred conditions at 10 °C, electrolyzed at 20 mA for 5 h; the reaction was stopped, ethyl acetate and water were added for extraction, washed with saturated sodium chloride solution, dried, and the solvent was evaporated to obtain 2-phenyl-1,2,3,4-tetrahydroquinoline with a yield of 50%.

[0076] The NMR spectrum data of the product are as follows: 1 H NMR (400 MHz, CDCl 3 ) δ 7.42-7.27 (m, 4H), 7.31-7.22 (m, 1H), 7.01(t, J = 7.2 Hz, 2H), 6.65 (td, J = 7.2, 1.2 Hz, 1H), 6.61-6.50 (m, 1H), 4.43 (m,1H), 4.03 (s, 1H), 2.92 (m, 1H), 2.73 (m, 1H), 2.12 (m, 1H), 1.99 (m, 1H),1.27 (d, J = 11.6 Hz, 4H), 0.92-0.81 (m, 1H). 13 C NMR (101 MHz, CDCl 3 ) δ 144.8, 144.8, 129.3, 128.6, 127.5, 126.9,126.6, 120.9, 117.2, 114.0, 56.3, 31.0, 26.4. The above data results show that the target product was synthesized.

[0077] Embodiment 17 In this embodiment, the target product is synthesized by selective hydrogenation of polycyclic aromatic hydrocarbons under electrochemical conditions and applied to the synthesis of (+ / -)-Rotigotine, a drug for the treatment of early Parkinson's disease. The steps are as follows:

[0078] (1) In a flow electrolyzer, a fixed carbon electrode (90 cm 2) as the anode and cathode, 5.0 mmol 1,6-dimethoxynaphthalene, 10 mmol tetra-n-butylammonium tetrafluoroborate, 20 mmol triethylamine, 1000 mL tetrahydrofuran and 400 mL acetonitrile were added, and electrolysis was carried out at 9 A current for 12 h under good stirring at room temperature; the reaction was stopped, ethyl acetate and water were added for extraction, and saturated sodium chloride solution was used for washing, and the organic solvent was evaporated to remove the crude intermediate product; acetone was added to dissolve the intermediate product, and 1 mol / L hydrochloric acid solution was added for acid hydrolysis, and stirred at room temperature. After the reaction was completed, crystallization was obtained to obtain 5-methoxy-2-tetralone (5M2T) with a yield of 70%; this step completed the selective hydrogenation in a flow electrochemical manner, indicating that the method of the present invention has good applicability and convenience in scale-up production; The NMR spectrum data of 5-methoxy-2-tetralone are as follows: 1 H NMR (400 MHz, CDCl 3 ) δ 7.19 (t, J = 8.0 Hz, 1H), 6.79-6.73 (m, 2H), 3.85 (s, 3H), 3.58 (s, 2H), 3.09 (t, J = 6.8 Hz, 2H), 2.53 (t, J = 6.4 Hz, 2H). 13 C NMR (101 MHz, CDCl 3 ) δ 211.31, 156.49, 135.08, 127.64, 125.10,120.56, 108.54, 55.59, 44.83, 38.03, 21.02. The above data results show that the target product was synthesized.

[0079]

[0080] (2) In a flask equipped with a magnetic field, add 3 mmol of 5-methoxy-2-naphthalene ketone, 10 mL of dichloromethane and 4 mmol of 2-thienylethylamine under an inert atmosphere, and then add 9 mmol of sodium triacetoxyborohydride (NaBH(OAc) 3 ); the reactant was stirred at room temperature for 24 h; the mixture was concentrated and 2 mol.L sodium hydroxide aqueous solution was added dropwise until pH = 8; the solution was extracted with ethyl acetate and water; the combined organic layer was washed with brine and dried over anhydrous sodium sulfate; after removing the solvent, the residue was mixed with 15 mmol potassium carbonate (K2 CO 3 ) were put into 10 mL of dimethyl sulfoxide and stirred for 1 h; 4 mmol 1-iodopropane was slowly added to the mixture and stirred overnight at room temperature; after the reaction was completed, the mixture was extracted three times with ethyl acetate and water, and washed with saturated brine. The organic layers were combined, dried over anhydrous sodium sulfate and concentrated. The residue was added with 10 mL of dichloromethane and 4 mmol of boron tribromide (BBr) at 0 °C. 3 ) and stirred overnight; after the reaction was completed, the reaction mixture was poured into ethyl acetate and washed three times with a saturated sodium bicarbonate solution; the organic phases were combined, dried over anhydrous sodium sulfate and concentrated to obtain rotigotine with a total yield of 49%.

[0081] The NMR spectroscopy data of rotigotine are as follows: 1 H NMR (400 MHz, CDCl 3 ) δ 7.13-7.12 (m, 1H), 6.99 (t, J = 8.0 Hz, 1H),6.94-6.91 (m, 1H), 6.82-6.81 (m, 1H), 6.67 (d, J = 7.6 Hz, 1H), 6.59 (d, J = 8.0Hz, 1H), 3.01-2.72 (m, 8H), 2.59-2.55 (m, 3H), 2.14-2.09 (m, 1H), 1.67-1.58(m, 1H), 1.52 (h, J = 7.6 Hz, 2H), 0.90 (t, J = 7.6 Hz, 3H). 13 C NMR (101 MHz, CDCl 3 ) δ 153.49, 143.18, 138.50, 126.72, 126.54,124.69, 123.42, 123.03, 121.87, 112.03, 56.80, 52.80, 52.76, 32.24, 29.96,25.70, 23.72, 22.20, 12.09. The above data results show that the target product was synthesized.

[0082] In order to further illustrate the principle of the present invention, the inventors combine the above embodiments and take typical naphthalene and its substitution products in polycyclic aromatic hydrocarbon compounds as examples and make the following explanations. The reaction principle of the cathode during the electrolysis process is shown in FIG.Figure 1 ; In the figure, R 1 is selected from the group consisting of hydrogen, hydroxy, dimethylamino, cyclohex-3-ene-1-carboxamide, fluorine, cyano, and methoxy; R 2 One selected from hydrogen, methoxy and ethyl 1-methylacetate.

[0083] like Figure 1 As shown, polycyclic aromatic hydrocarbons are first reduced to aromatic radical anions at the cathode, and then combine with protons to generate aromatic radicals. The aromatic radicals can be hydrogenated through further cathode reduction and proton combination. Among them. Organic solvents achieve selective hydrogenation by affecting the rate of generation and migration of anode protons during electrolysis. The diffusion rate of protons released by the anode in olefin-forming organic solvents is slow, and only the process of electrochemical reduction of aromatics exists in the reaction; while in alkane-forming organic solvents, the proton diffusion rate is fast, hydrogen ions can be further reduced to hydrogen radicals, and hydrogen radicals further reduce olefins to alkane products. There are two processes in the reaction: electrochemical reduction and hydrogen radical reduction.

[0084] In summary, the method for selective hydrogenation of polycyclic aromatic hydrocarbons under electrochemical conditions of the present invention realizes the preparation of alkenyl-substituted aromatic hydrocarbons or alkyl-substituted aromatic hydrocarbons with high selectivity under current drive, and has the advantages of cheap and readily available raw materials, green environmental protection, and safe and mild reaction conditions. The method of the present invention has good application potential in the modification and synthesis of drugs and chemical raw materials.

[0085] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A method for selective hydrogenation of polycyclic aromatic hydrocarbons under electrochemical conditions, characterized in that: The steps include: In an inert atmosphere, polycyclic aromatic hydrocarbon compounds are mixed with an organic amine additive, an electrolyte, and an organic solvent to obtain an electrolyte; the electrolyte is electrolyzed under the action of direct current to complete selective hydrogenation, and hydrogenated aromatic hydrocarbons are obtained after separation and purification; The polycyclic aromatic hydrocarbon compounds include polycyclic aromatic hydrocarbons having 2-5 aromatic rings and their substitutes; the organic solvent includes an olefin-forming organic solvent or an alkane-forming organic solvent; the hydrogenated aromatic hydrocarbons include an olefin-substituted aromatic hydrocarbon or an alkyl-substituted aromatic hydrocarbon; in the preparation process of the electrolyte, the olefin-forming organic solvent or the alkane-forming organic solvent is selected according to the product form of the target olefin-substituted aromatic hydrocarbon or alkyl-substituted aromatic hydrocarbon; The olefin-forming organic solvent includes at least one of tetrahydrofuran, dioxane, and acetonitrile; the alkane-forming organic solvent includes N,N -dimethylformamide, N,N - At least one of dimethylacetamide and dimethyl sulfoxide.

2. The method for selective hydrogenation of polycyclic aromatic hydrocarbons under electrochemical conditions according to claim 1, characterized in that: The polycyclic aromatic hydrocarbons include one of naphthalene, anthracene, perylene, carbazole, benzofuran, dibenzofuran, dibenzothiophene, biphenyl, and quinoline; in the substituents of the polycyclic aromatic hydrocarbons, the substituents include at least one of phenyl, hydroxyl, dimethylamino, cyclohex-3-ene-1-carboxamide, fluorine, cyano, methoxy, and ethyl 1-methylacetate.

3. The method for selective hydrogenation of polycyclic aromatic hydrocarbons under electrochemical conditions according to claim 2, characterized in that: The polycyclic aromatic hydrocarbon compounds include naphthalene, N -phenylcarbazole, perylene, dibenzofuran, dibenzothiophene, benzofuran, 1-naphthol, N, N - one of dimethyl-1-naphthylamine, cyclohex-3-ene-1-carboxamidonaphthalene, 1-fluoronaphthalene, 2-naphthalenenitrile, naproxen ethyl ester, terphenyl, 2-phenylquinoline, and 1,6-dimethoxynaphthalene.

4. The method for selective hydrogenation of polycyclic aromatic hydrocarbons under electrochemical conditions according to claim 1, characterized in that: The organic amine additives include triethylamine, trimethylamine, tri-n-butylamine, N,N - at least one of diisopropylethylamine, dibenzylamine and diethylamine.

5. The method for selective hydrogenation of polycyclic aromatic hydrocarbons under electrochemical conditions according to claim 1, characterized in that: The electrolyte includes at least one of tetra-n-butylammonium hexafluorophosphate, tetra-n-butylammonium bromide, tetra-n-butylammonium tetrafluoroborate, tetraethylammonium chloride, lithium bromide, and lithium perchlorate.

6. The method for selective hydrogenation of polycyclic aromatic hydrocarbons under electrochemical conditions according to claim 1, characterized in that: Preferably, the molar ratio of the polycyclic aromatic hydrocarbon compound, the electrolyte, and the organic amine additive is 1:(0.2-2):(1-12) respectively.

7. The method for selective hydrogenation of polycyclic aromatic hydrocarbons under electrochemical conditions according to claim 1, characterized in that: The current density of the electrolysis is 2-100 mA / cm 2 ; The ambient temperature for electrolysis is 0-50 ℃; The duration of electrolysis is 3-12 h.

8. The method for selective hydrogenation of polycyclic aromatic hydrocarbons under electrochemical conditions according to claim 1, characterized in that: In the electrolytic electrodes, the anode includes one of a carbon electrode or a platinum electrode; the cathode includes one of a carbon electrode or a lead electrode.

9. Use of the method for selective hydrogenation of polycyclic aromatic hydrocarbons under electrochemical conditions according to any one of claims 1 to 8 in the synthesis of chemical raw materials and drugs.

10. Use of the method for selective hydrogenation of polycyclic aromatic hydrocarbons under electrochemical conditions according to claim 9, characterized in that: The method for selective hydrogenation of polycyclic aromatic hydrocarbons under electrochemical conditions is used to synthesize the pharmaceutical intermediate 5-methoxy-2-tetralone, which is used for the preparation of the drug rotigotine.

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