A preparation method of a pyrrolo[2,3-e]indole hydrogen storage material

Abstract

The application belongs to the technical field of organic hydrogen storage material preparation, and particularly relates to a preparation method of a pyrrolo[2,3-e]indole hydrogen storage material. The preparation method comprises the following steps: in a reactor, benzene diamine and o-diol, catalyst alpha and catalyst beta are put in, then reaction is carried out at 25-250 DEG C for 0.1-48 hours, and pyrrolo[2,3-e]indole compounds are obtained; the catalyst alpha is a catalyst with hydrogen activation ability and dehydrogenation ability; the catalyst beta is an acid with Hammett acidity function H0 < 0. The application provides a method for preparing the hydrogen storage material pyrrolo[2,3-e]indole compounds, benzene diamine and diol are used for reaction, two catalysts are used, and a one-step closed double ring is realized, and the atom economy is high. The starting material of the application is cheap and easy to obtain, and is easy to be industrialized, and helps hydrogen energy industry. The method of the application has high universality and high substrate tolerance.

Description

Technical Field

[0001] This invention belongs to the field of organic hydrogen storage material preparation technology, specifically relating to a method for preparing pyrrolo[2,3-e]indole hydrogen storage materials. Background Technology

[0002] Patent CN113233413A mentions a hydrogen storage material, pyrrolo[2,3-e]indole (molecule M4 as claimed in claim 2). Compared with previously reported carbazole, indole, and benzylbenzene organic hydrogen storage materials, it has a lower hydrogenation / dehydrogenation reaction temperature, more stable molecular properties, and higher reaction efficiency, making it an ideal hydrogen storage material. However, there are currently few references for the synthesis of such materials. If the classic Fischer process is used to close the bicyclic rings, it requires raw materials such as m-phenylenedihydrazine and strong acids, which are highly toxic and corrosive. If phenylenediamines are used, such as those mentioned in J. Chem. Soc., 1953, 4114-4116, which describes the synthesis of pyrrolo[2,3-e]indole by reacting phenylenediamines with hydroxy ketones, there are problems such as the difficulty in obtaining hydroxy ketones and the high cost of raw materials.

[0003] The molecular M4 structural formula of claim 2 in patent CN113233413A is as follows:

[0004] .

[0005] Therefore, there is an urgent need for a suitable industrial-scale preparation method. To address these issues, this invention is proposed. Summary of the Invention

[0006] This invention provides a one-step method for preparing pyrrolo[2,3-e]indole compounds, which are used as hydrogen storage materials.

[0007] In a reactor, phenylenediamines and vicinal diols, catalysts α and β, and solvent are added in a certain proportion, and the reaction is carried out at 150-180℃ for 0.5-24 hours to obtain pyrrolo[2,3-e]indole compounds.

[0008] The structural formulas of pyrrolo[2,3-e]indole compounds are as follows:

[0009] ;

[0010] The reaction equations for the above reactions are as follows:

[0011] .

[0012] The phenylenediamine class includes alkyl-substituted homologues of the ring or nitrogen atom of the meta-phenylenediamine, particularly meta-phenylenediamine, N-methylphenylenediamine, N1,N3-dimethylphenyl-1,3-diamine, N-ethylphenylenediamine, N1,N3-dibutylphenyl-1,3-diamine, 2,4-diaminotoluene, 5-methylphenyl-1,3-diamine, etc.

[0013] The general structural formula of the phenylenediamine class is as follows:

[0014] ;

[0015] R1 and R2 may be the same or different, and R1 and R2 are independently derived from H atoms or alkyl groups containing 1-4 carbons;

[0016] R3 and R4 may be the same or different, and R3 and R4 may be independently derived from H or methyl groups;

[0017] The aforementioned vicinal diols refer to alkyl-substituted homologues of ethylene glycol at the 1 or 2 position, particularly ethylene glycol, 1,2-propanediol, 2,3-butanediol, 1,2-cyclohexanediol, 1,2-hexanediol, etc.

[0018] The general structural formula of the vicinal diols is as follows: A or B;

[0019] ;

[0020] In formula A, R5 and R6 may be the same or different, and R5 and R6 are derived from H atoms or alkyl groups containing 1-4 carbons;

[0021] The molar ratio of the phenylenediamine and the vicinal diol is 1:2 to 1:10.

[0022] The molar ratio of phenylenediamine to catalyst α is 1:0.01 to 1:0.05.

[0023] The molar ratio of phenylenediamine to catalyst β is 1:0.05-1:0.1.

[0024] The catalyst α is a catalyst that simultaneously possesses hydrocarbon activation and dehydrogenation capabilities, including noble metal catalysts, transition metal catalysts, and alloys of both. Specifically, it refers to: palladium-carbon, ruthenium-molecular sieve, palladium-silica / alumina, Pt-LDH (layered double hydroxide), platinum-zinc-alumina, nickel-silica-alumina, copper-alumina, silver-copper-silica, etc.

[0025] The catalyst β is an acid with a Hammett acidity function H0 < 0, specifically referring to: zirconium oxide superacid (zirconia sulfate), p-toluenesulfonic acid, perfluorobutylsulfonic acid, perfluorosulfonic acid resin (Nafion-H), zirconium tungstate, etc.

[0026] The reactor is an organic synthesis reaction device, specifically referring to reaction flasks, reaction kettles, fixed-bed reaction devices, microchannel reaction devices, and loop reactors.

[0027] Preferably, the crude product after the reaction is purified and separated by filtration.

[0028] In the reactor, solvents may be added, either alone or in combination.

[0029] The solvent is a high-boiling-point solvent, especially a liquid with a boiling point above 200°C. For example, one or more of N-methylpyrrolidone, sulfolane, ethylene carbonate, tetraethylene glycol dimethyl ether, 1-butyl-3-methylimidazolium trifluoromethanesulfonate (ionic liquid), 1-ethyl-3-methylimidazolium tetrafluoroborate (ionic liquid), etc.

[0030] Preferably, the reaction temperature is 150-180℃; the reaction time is 0.5-24 hours.

[0031] The purification methods include one or more of the following organic synthesis purification methods: centrifugation, filtration, distillation, extraction, column chromatography, recrystallization, etc.

[0032] Preferably, the above reaction is carried out with or without stirring.

[0033] The beneficial effects of this invention are as follows:

[0034] 1. This application provides a method for preparing pyrrolo[2,3-e]indole compounds for hydrogen storage, which uses phenylenediamine and diol reactions and two catalysts to achieve one-step bicyclic closure with high atom economy.

[0035] 2. The starting materials used in this application are inexpensive and readily available, making them easy to industrialize and contributing to the hydrogen energy industry.

[0036] 3. The method of this application has high versatility and high substrate tolerance. Attached Figure Description

[0037] Figure 1 The image shows the ¹H-NMR nuclear magnetic resonance spectrum of 1,6-dihydropyrrole[2,3-e]indole synthesized in Example 2.

[0038] Figure 2 The image shows the ¹H-NMR spectrum of 1,2,3,4,5,8,9,10,11,12-decahydroindole[32,a]carbazole synthesized in Example 8. Detailed Implementation

[0039] The present invention will be described below with reference to specific embodiments, but the implementation of the present invention is not limited thereto. Experimental methods not specifically described in the embodiments generally use conventional conditions and conditions described in the manual, or conditions recommended by the manufacturer. The general equipment, materials, reagents, etc., used are all commercially available unless otherwise specified. The raw materials required in the following embodiments and comparative examples are all commercially available.

[0040] Unless otherwise specified, all percentages in this application are mass percentages.

[0041] Example 1 Synthesis of N,N-1,6-dimethylpyrrolo[2,3-e]indole

[0042] 5% palladium-carbon, i.e., carbon-supported palladium, with a palladium loading of 5 wt%.

[0043] Zirconia superacid (zirconia sulfate) was purchased from Guangdong Wengjiang Chemical Reagent Co., Ltd., with a loading rate of 15% and product number YA139992.

[0044] N1,N3-Dimethylphenyl-1,3-diamine, CAS No. 14814-75-6, Structural formula: .

[0045] The synthesis method of N,N-1,6-dimethylpyrrole[2,3-e]indole is as follows:

[0046] In a 500 ml high-pressure reactor, 13.6 g (0.1 mol) of N1,N3-dimethylphenyl-1,3-diamine and 14.4 g (0.2 mol) of ethylene glycol were added, along with 4.3 g (0.002 mol) of 5% palladium-carbon and 2.8 g (0.01 mol) of zirconium oxide superacid (zirconia sulfate). 100 g of N-methylpyrrolidone was then added. The mixture was heated to 150 °C and reacted for 8 hours. The reaction was then stopped. The crude product was filtered through a Buchner funnel, the catalyst was recovered, and the filtrate was extracted using a water-ethyl acetate system. The organic phase was concentrated by distillation to obtain 10 g of a white solid, N,N-1,6-dimethylpyrrole[2,3-e]indole. The yield of N,N-1,6-dimethylpyrrole[2,3-e]indole was calculated to be 54.3%.

[0047] The structure of the N,N-1,6-dimethylpyrrole[2,3-e]indole compound prepared by the above method was identified by the following method:

[0048] ¹H-NMR (400 MHz, CDCl3) : 3.73ppm (s, 3H), 4.02ppm (s, 3H), 6.46ppm (m, 1H), 6.70ppm (m, 1H), 6.85ppm (s, 1H), 6.95ppm (s, 1H), 7.01-7.03ppm (m, 1H), 7.36-7.39ppm (m, 1H).

[0049] Therefore, it can be determined from the above that the structural formula of the compound is: Its name is N,N-1,6-dimethylpyrrole[2,3-e]indole.

[0050] Example 2 Synthesis of 1,6-dihydropyrrole[2,3-e]indole

[0051] The palladium-silica / alumina spheres (particle size = 1 mm) were sourced from Shaanxi Ruike New Material Co., Ltd., with a palladium loading of 5%.

[0052] Perfluorobutylsulfonic acid CAS No. 375-73-5.

[0053] The synthesis method of 1,6-dihydropyrrole[2,3-e]indole is as follows:

[0054] In a fixed-bed reactor, the column temperature was controlled at 180℃. An 18ml column was filled with 15g of 5% palladium-silica / alumina spheres (particle size = 1mm). After hydrogen activation of the bed, the hydrogen flow rate was controlled at 20ml / min. A horizontal flow pump was used to control the injection rate at 0.5ml / min. The injection solution was a m-phenylenediamine-ethylene glycol solution (m-phenylenediamine to ethylene glycol molar ratio of 10%), with perfluorobutylsulfonic acid added as a catalyst. The molar ratio of m-phenylenediamine to perfluorobutylsulfonic acid was 1:0.05. After 1 hour, the eluent was collected as the crude product. Water was added to the crude product for precipitation, resulting in a grayish-brown solid. The grayish-brown solid was recrystallized from 75% ethanol to obtain a white solid, identified as 1,6-dihydropyrrole[2,3-e]indole. The yield of 1,6-dihydropyrrole[2,3-e]indole was calculated to be 88%.

[0055] The method for identifying off-white solids is ¹H-NMR:

[0056] ¹H-NMR (600 MHz, CDCl3): 6.69ppm (m,2H), 7.13-7.14ppm (m,1H), 7.18-7.19ppm m,1H),7.21-7.23ppm(d,J=9Hz,1H),7.50-7.52ppm(d,J=9Hz,1H),8.25ppm(m,1H),8.38ppm(m,1H).

[0057] Therefore, it can be determined from the above that the structural formula of the off-white solid is: Its name is 1,6-dihydropyrrole[2,3-e]indole.

[0058] Appendix Figure 1 The 1,6-dihydropyrrole[2,3-e]indole is ¹H-¹H-COSY (600 MHz, CDCl3), and the two hydrogens on the benzene ring are related, confirming it as the target structure.

[0059] Example 3 Synthesis of 3,8-dibutyl-4-methyl-1,6-dihydropyrrole[2,3-e]indole

[0060] The 65% nickel-silica-alumina catalyst was purchased from Aladdin, item number N475374-25g.

[0061] The CAS number for 2,4-diaminotoluene is 95-80-7, and its structural formula is: .

[0062] CAS number for 1,2-hexanediol is 6920-22-5. CAS number for tetraethylene glycol dimethyl ether is 143-24-8.

[0063] Zirconium tungstate was purchased through Aladdin, item number T141456.

[0064] In a 100 ml reaction flask, 6.1 g (0.05 mol) of 2,4-diaminotoluene, 17.7 g (0.15 mol) of 1,2-hexanediol, 0.23 g (0.0025 mol) of 65% nickel-silica-alumina catalyst, and 0.7 g (0.003 mol) of zirconium tungstate were added, along with 60 g of tetraethylene glycol dimethyl ether. The system was stirred until homogeneous. The mixture was then heated to 170 °C and reacted for 12 hours. The reaction was stopped, and the suspension was centrifuged to recover the catalyst. The clear liquid was washed twice with 100 ml of deionized water. The organic phase was dried over anhydrous sodium sulfate and then concentrated using a rotary evaporator to obtain 6 g of a pale yellow liquid, which was identified as 3,8-dibutyl-4-methyl-1,6-dihydropyrrole[2,3-e]indole, with a yield of 42.6%.

[0065] The structure of the pale yellow liquid was determined by ¹H-NMR analysis, and the results are as follows:

[0066] ¹H-NMR (400 MHz, CDCl3) : 0.83-0.88ppm (m, 6H), 1.22-1.43ppm (m, 4H), 1.60-1.66ppm (m, 4H), 2.65ppm (s, 3H), 2.75-2.80ppm (m, 2H), 2.85-2 .90ppm (m,2H), 7.11-7.13ppm (m,1H), 7.18-7.20ppm (m,1H), 7.24-7.30ppm (m,1H), 7.97ppm (s,1H), 8.12ppm (s,1H).

[0067] Therefore, it can be determined from the above that the structural formula of the compound is: Its name is 3,8-dibutyl-4-methyl-1,6-dihydropyrrole[2,3-e]indole.

[0068] Example 4: Synthesis of 2,3,6,7,8-pentamethyl-1-hydropyrrolo[2,3-e]indole

[0069] CAS No. 50617-73-7 for N-methyl-m-phenylenediamine, CAS No. 513-85-9 for 2,3-butanediol, CAS No. 174899-66-2 for 1-butyl-3-methylimidazolium trifluoromethanesulfonate, and CAS No. 104-15-4 for p-toluenesulfonic acid.

[0070] A 2% silver-copper-silicon oxide catalyst was prepared by an equal-volume impregnation method: First, the SiO2 support was activated by calcination at 550 °C. Then, silver nitrate and copper nitrate precursors were weighed according to a total loading of 2 wt% silver and a silver-copper atomic ratio of 1:1, dissolved in deionized water to prepare a mixed solution, and added dropwise to the SiO2 support. The mixture was impregnated at room temperature for 12 h, dried at 120 °C for 12 h, and calcined at 500 °C for 5 h in air. Finally, it was reduced at 350 °C for 3 h under a H2 / N2 atmosphere to obtain the 2% silver-copper-silicon oxide catalyst.

[0071] In a 1L tubular reactor, 48.8g (0.4mol) of N-methyl-m-phenylenediamine, 180g (2mol) of 2,3-butanediol, 4.9g of 1-butyl-3-methylimidazolium trifluoromethanesulfonate (ionic liquid), 21.6g of 2% silver-copper-silica catalyst (0.004mol), and 4.8g (0.028mol) of p-toluenesulfonic acid were added and stirred until homogeneous. The reactor temperature was then maintained at 150℃, the loop temperature at 180℃, and the system was kept under vacuum (≤2000pa) with stirring for 8 hours. The reaction was stopped, and the reaction solution was filtered using a small bag filter. 200g of ethyl acetate and 200g of water were added to the filtrate, and the mixture was extracted and separated using a 2L separatory funnel. The organic phase was then washed once with 200g of water. The organic phase was concentrated, and then purified by column chromatography with silica gel. The mobile phase was ethyl acetate:dichloromethane 1:10. Finally, 20 g of grayish-white solid was obtained, which was identified as 2,3,6,7,8-pentamethyl-1-hydropyrrole[2,3-e]indole, with a yield of 22.1%.

[0072] The structure of the grayish-white solid was determined by ¹H-NMR analysis, and the results are as follows:

[0073] ¹H-NMR (400 MHz, CDCl3): 2.29ppm (s,3H), 2.39ppm (s,3H), 2.44ppm (s,3H), 2.49ppm (s,3H), 3.56ppm (s,3H), 7.04-7.06ppm (d,J=8Hz,1H),

[0074] 7.20-7.22ppm(d,J=8Hz,1H),7.73ppm(m,1H).

[0075] Therefore, it can be determined from the above that the structural formula of the compound is: Its name is 2,3,6,7,8-pentamethyl-1-hydropyrrole[2,3-e]indole.

[0076] Example 5: Synthesis of 4-methyl-1,6-dihydropyrrole[2,3-e]indole

[0077] The preparation method of 5% platinum-zinc-alumina is as follows:

[0078] Carrier pretreatment: γ-alumina was calcined in a muffle furnace at 550℃ for 4 hours and dried for later use to obtain γ-alumina carrier.

[0079] Impregnation solution preparation: The precursor was prepared with a platinum loading of 5 wt% and a platinum / zinc atomic ratio of 1:0.5. The precursors were chloroplatinic acid and zinc nitrate, dissolved in water according to the saturated water absorption capacity of the support. The pH was adjusted to 2-3 with dilute hydrochloric acid to prevent hydrolysis, resulting in the impregnation solution. The 5 wt% platinum loading refers to a mass ratio of platinum to γ-alumina support of 5 wt%.

[0080] Co-impregnation: The γ-alumina support is added to the impregnation solution and allowed to stand at room temperature for 16 hours with intermittent stirring.

[0081] Drying and calcination: The impregnated carrier is dried at 110℃ for 12 hours and then calcined in air at 450℃ for 3 hours to ensure uniform dispersion of elements.

[0082] Reduction: Using 10 vol% H2 / N2 as the reducing gas, the dried and calcined material was reduced at 500℃ for 3 hours. During this time, zinc atoms diffused into the platinum lattice, completing the 5% platinum-zinc-alumina catalytic preparation. 10 vol% H2 / N2 refers to a hydrogen to nitrogen volume ratio of 1:9.

[0083] The perfluorosulfonic acid resin (Nafion-H) was purchased from Maclean's, product number N875244.

[0084] 5-Methylbenzene-1,3-diamine CAS No. 108-71-4.

[0085] The synthesis method of 4-methyl-1,6-dihydropyrrole[2,3-e]indole is as follows:

[0086] In the microchannel reaction apparatus, the column temperature was controlled at 160℃. A 7.8 ml column was filled with a well-mixed dual catalyst (4 g 5% platinum zinc-alumina (particle size = 0.05 mm) and 3 g perfluorosulfonic acid resin (Nafion-H)). The column was first purged with nitrogen at a rate of 20 ml / min. The three-way valve was then switched, and the catalyst was activated with hydrogen at a rate of 20 ml / min for 1 hour. The hydrogen flow rate was controlled at 20 ml / min. The high-pressure plunger pump was started, and the liquid flow rate was controlled at 0.05 ml / min. The injection solution was a mixed solution of 5-methylbenzene-1,3-diamine / ethylene glycol / sulfolane, in which the molar ratio of 5-methylbenzene-1,3-diamine / ethylene glycol was 1:4, and the total mass of both and the mass ratio of sulfolane was 30%.

[0087] After 0.5 hours, the eluent was collected. Water was added to the liquid to precipitate a brownish-yellow solid. The solid was recrystallized from isopropanol to give a yellow powder, which was identified as 4-methyl-1,6-dihydropyrrole[2,3-e]indole, with a yield of 89%.

[0088] The structure of the yellow powder was determined by ¹H-NMR analysis, and the results are as follows:

[0089] ¹H-NMR (400 MHz, CDCl3) : 2.58ppm (s, 3H), 6.62-6.64ppm (m, 1H), 6.66-6.68ppm (m, 1H), 7.09-7.10ppm (m, 1 H), 7.17-7.20ppm (m,1H), 7.24-7.30ppm (m,1H), 8.17ppm (s,1H), 8.31ppm (s,1H).

[0090] Therefore, it can be determined from the above that the structural formula of the compound is: Its name is 4-methyl-1,6-dihydropyrrole[2,3-e]indole.

[0091] Example 6: Synthesis of N,N-1,6-Butylpyrrole[2,3-e]indole:

[0092] N1,N3-Dibutylphenyl-1,3-diamine was synthesized using the method described in the European Journal of Organic Chemistry, 2014, vol. 2014, # 35, p. 7895 - 7905.

[0093] .

[0094] S1 Synthesis: m-Phenylenediamine (324 g) and p-toluenesulfonyl chloride (1258 g) were dissolved in pyridine (2.5 L). The mixture was heated at 120 °C with continuous stirring for 2 h. After cooling to room temperature, 0.1 N hydrochloric acid was added to precipitate the product. The solid product was collected by filtration, thoroughly washed with water, and the dried solid was further recrystallized from 95% ethanol to give S1 (1001 g), yield 80%.

[0095] S2 Synthesis: S1 (560 g) was dissolved in a mixture of acetone (10 L) and water (5 L), and sodium hydroxide (216 g) was added with continuous stirring at room temperature. The temperature of the resulting mixture was gradually increased to 80°C, and bromobutane (1110 g) was added dropwise. After stirring at 80°C for 10 hours, the reaction mixture was cooled to room temperature and extracted with ethyl acetate (3 × 7500 ml). The combined organic layers were dried over anhydrous magnesium sulfate, filtered, and concentrated. Purification was achieved by recrystallization from ethyl acetate / petroleum ether (1:5) to give 500 g of white solid S2 in 70% yield.

[0096] Synthesis of N1,N3-dibutylphenyl-1,3-diamine: S2 (106 g) was mixed with concentrated sulfuric acid (150 ml) and heated at 80°C for 4 hours. After cooling to room temperature, the reaction mixture was neutralized with sodium hydroxide (0.1 mol / L) and then extracted with ethyl acetate (5 × 500 ml). The mixed organic layer was dried over anhydrous magnesium sulfate, filtered, and then concentrated under vacuum to give a brown oil. Recrystallization from a mixture of petroleum ether and acetone (5:1) gave 40 g of pure pale yellow solid N1,N3-dibutylphenyl-1,3-diamine, in 91% yield.

[0097] 10% copper-alumina was purchased from Shanghai Xunkai Catalysis, model CuCAT-2400P.

[0098] The synthesis method of N,N-1,6-butylpyrrole[2,3-e]indole is as follows:

[0099] In a 1000 ml high-pressure reactor, 22 g (0.1 mol) of N1,N3-dibutylphenyl-1,3-diamine and 28.8 g (0.4 mol) of ethylene glycol were added, along with 3.17 g (0.005 mol) of 10% copper-alumina and 5.62 g (0.01 mol) of perfluorobutylsulfonic acid. 100 g of ethylene carbonate was added, and the mixture was heated to 180 °C and reacted for 24 hours. The reaction was then stopped, and the crude product was filtered through a Buchner funnel to recover the catalyst. The filtrate was then mixed with 100 g of water and 100 g of butyl acetate and transferred to an extraction tower for extraction. The organic phase was concentrated by distillation, and the paste-like crude product was purified by silica gel column chromatography using ethyl acetate:petroleum ether at a mobile phase of 1:5. Finally, 5 g of an oily substance was obtained, identified as N,N-1,6-dibutylpyrrole[2,3-e]indole. The yield was 18.6%.

[0100] The structure of the oily substance was determined by ¹H-NMR analysis, and the results are as follows:

[0101] ¹H-NMR (400 MHz, CDCl3): 0.81-0.87ppm (m,6H), 1.19-1.40ppm (m,4H), 1.71-1.84ppm (m,4H), 4.02-4.06ppm (t,J=8,2H), 4.22-4.26ppm (t,J=8,2H)

[0102] 6.44ppm(s,1H),6.57ppm(s,1H),6.85ppm(s,1H),6.96ppm(s,1H),7.00-7.04ppm(m,1H),7.33-7.34ppm(m,1H).

[0103] Therefore, it can be determined from the above that the structural formula of the compound is: Its name is N,N-1,6-dibutylpyrrole[2,3-e]indole.

[0104] Example 7: Synthesis of 6-ethyl-3,8-dimethyl-1-hydropyrrole[2,3-e]indole

[0105] Azoethyl-m-phenylenediamine CAS No. 50617-74-8, 1-ethyl-3-methylimidazolium tetrafluoroborate (ionic liquid) 143314-16-3.

[0106] The 5% ruthenium-molecular sieve is a molecular sieve-supported ruthenium material purchased from Shaanxi Ruike New Material Co., Ltd., named ruthenium molecular sieve catalyst, CAS number 7440-18-8, with a loading of 5wt%.

[0107] In a 1L tubular reactor, 13.6 g (0.1 mol) of ethyl-m-phenylenediamine, 15.2 g (0.2 mol) of 1,2-propanediol, 1.4 g of 1-ethyl-3-methylimidazolium tetrafluoroborate (ionic liquid), 100 g of ethylene carbonate, 4 g of 5% ruthenium-molecular sieve (0.002 mol), and 4.8 g (0.028 mol) of p-toluenesulfonic acid were added and stirred until homogeneous. The reactor temperature was then maintained at 150°C, the loop temperature at 175°C, and the system was kept under vacuum (≤2000 Pa) for 10 hours. The reaction was stopped, and the reaction solution was filtered using a Buchner funnel / vacuum flask. 200 g of water was added to the filtrate to separate the layers, and the organic phase was dried over anhydrous magnesium sulfate. The organic phase was concentrated to obtain a brown semi-solid. Further purification by silica gel column chromatography with ethyl acetate:petroleum ether 1:5 as the mobile phase yielded 15g of yellow-brown semi-solid, which was identified as 6-ethyl-3,8-dimethyl-1-hydropyrrole[2,3-e]indole, with a yield of 70.7%.

[0108] The structure of the yellowish-brown semi-solid was determined by ¹H-NMR analysis, and the results are as follows:

[0109] ¹H-NMR (400 MHz, CDCl3): 1.49-1.52ppm (m, 3H), 2.51ppm (s, 3H), 2.63ppm (s, 3H), 4.32-4.37ppm (m, 2H) ),6.50ppm(s,1H),6.77ppm(s,1H),7.25ppm(s,1H),7.28ppm(s,1H),7.90ppm(s,1H).

[0110] Therefore, it can be determined from the above that the structural formula of the compound is: Its name is 6-ethyl-3,8-dimethyl-1-hydropyrrole[2,3-e]indole.

[0111] Example 8, Synthesis of 1,2,3,4,5,8,9,10,11,12-decahydroindole[32,a]carbazole:

[0112] 5% Pt-LDH (layered double hydroxide) was prepared by precipitation method: the layered double metal hydroxide (LDH) support was dispersed in deionized water to form a uniform suspension. Chloroplatinic acid precursor was weighed at 5 wt% of Pt loading and dissolved in water. It was slowly added dropwise to the LDH suspension. The pH of the system was adjusted to 8.0–9.0 with dilute urea solution under stirring. The system was aged at room temperature for 2–4 h to allow platinum species to be uniformly deposited on the LDH surface. Then, the system was filtered, washed twice with deionized water, and vacuum dried at 60–80 °C for 12 h. Finally, the system was reduced at 200–300 °C for 2 h in a hydrogen / argon mixed gas to obtain the 5% Pt / LDH catalyst.

[0113] In a 500 ml high-pressure reactor, 10.8 g (0.1 mol) of m-phenylenediamine and 34.8 g (0.3 mol) of 1,2-cyclohexanediol were added, along with 3.4 g (0.001 mol) of 5% Pt-LDH and 2.8 g (0.01 mol) of zirconium oxide superacid (zirconia sulfate). 100 g of N-methylpyrrolidone was then added, and the mixture was heated to 180 °C and reacted for 4 hours. The reaction was then stopped. The crude product was then filtered through a Buchner funnel to recover the catalyst. The filtrate was extracted using a water-ethyl acetate system, the organic phase was concentrated by distillation, and ethylene glycol dimethyl ether was added to form a slurry. After filtration, 12 g of a white solid was obtained, identified as 1,2,3,4,5,8,9,10,11,12-decahydroindole[32,a]carbazole, with a yield of 45.5%.

[0114] The structure of the white solid was determined by ¹H-NMR analysis, and the results are as follows:

[0115] ¹H-NMR (400 MHz, CD3OD) :0.91-1.95ppm(m,8H),2.70-2.72ppm(m,2H),2.76-2.81ppm(m,4H),2.98-3 .00ppm(m,2H),6.95-6.97ppm(d,J=12Hz,1H),7.02-7.04ppm(d,J=12Hz,1H).

[0116] Therefore, it can be determined from the above that the structural formula of the compound is: The name is 1,2,3,4,5,8,9,10,11,12-decahydroindole[32,a]carbazole.

[0117] Appendix Figure 2The ¹H-¹H-COSY (600MHz, CD3OD) of 1,2,3,4,5,8,9,10,11,12-decahydroindole[32,a]carbazole showed two hydrogen atom correlations on the benzene ring, confirming it as the target structure.

Claims

1. A method for preparing a pyrrolo[2,3-e]indole hydrogen storage material, characterized in that, The preparation method includes the following steps: In a reactor, phenylenediamines and vicinal diols, catalyst α and catalyst β are added, and the reaction is carried out at 25-250°C for 0.1-48 hours to obtain pyrrolo[2,3-e]indole compounds; The molar ratio of the phenylenediamine and the vicinal diol is 1:0.5-1:20; The molar ratio of the phenylenediamine to catalyst α is 1:0.001-1:0.1; The molar ratio of the phenylenediamine to catalyst β is 1:0.005-1:0.1; The catalyst α is a catalyst that simultaneously possesses hydrocarbon activation and dehydrogenation capabilities; The catalyst β is an acid whose Hammett acidity function H0 < 0; The general structural formula of the phenylenediamine class is as follows: ； R1 and R2 may be the same or different, and R1 and R2 are independently derived from H atoms or 1-4 carbon alkyl groups; R3 and R4 may be the same or different, and R3 and R4 may be independently derived from H or methyl groups; The general structural formula of the vicinal diols is as follows: (A) or (B); ； In formula A, R5 and R6 may be the same or different, and R5 and R6 are derived from H atoms or 1-4 carbon alkyl groups; The general structural formula of the pyrrolo[2,3-e]indole compounds is as follows: ； Or the pyrrolo[2,3-e]indole compound is... .

2. The preparation method according to claim 1, characterized in that, The phenylenediamines are selected from one or more of the following: m-phenylenediamine, N-methylphenylenediamine, N1,N3-dimethylphenyl-1,3-diamine, N-ethylphenylenediamine, N1,N3-dibutylphenyl-1,3-diamine, 2,4-diaminotoluene, and 5-methylphenyl-1,3-diamine.

3. The preparation method according to claim 1, characterized in that, The vicinal diols are selected from one or more of the following: ethylene glycol, 1,2-propanediol, 2,3-butanediol, 1,2-cyclohexanediol, and 1,2-hexanediol.

4. The preparation method according to claim 1, characterized in that, The catalyst α comprises one or more of noble metals, non-noble metals, and their alloys.

5. The preparation method according to claim 1, characterized in that, The catalyst β is selected from one or more of the following: zirconium sulfate, p-toluenesulfonic acid, perfluorobutylsulfonic acid, perfluorosulfonic acid resin, and zirconium tungstate.

6. The preparation method according to claim 1, characterized in that, Add a liquid with a boiling point above 200°C as a solvent to the reactor, or do not add a solvent to the reactor.

7. The preparation method according to claim 1, characterized in that, The reaction temperature is 150-180℃; The reaction time is 0.5-24 hours.

8. The preparation method according to claim 1, characterized in that, The solvent is one or more of N-methylpyrrolidone, sulfolane, ethylene carbonate, tetraethylene glycol dimethyl ether, 1-butyl-3-methylimidazolium trifluoromethanesulfonate, and 1-ethyl-3-methylimidazolium tetrafluoroborate.

9. The preparation method according to claim 1, characterized in that, The molar ratio of the phenylenediamine and the vicinal diol is 1:2 to 1:10; The molar ratio of the phenylenediamine to catalyst α is 1:0.01-1:0.05; The molar ratio of the phenylenediamine to catalyst β is 1:0.05-1:0.1.

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