Method for synthesizing nitrogen-containing aromatic compounds by one-step photocatalytic lignin depolymerization and amination

A technology for aromatic compounds and lignin, applied in the application field of lignin, can solve the problems of requiring high temperature or high pressure, harsh reaction conditions, complicated reaction steps, etc., and achieves the effects of high conversion rate, mild reaction conditions and convenient operation.

Active Publication Date: 2019-08-23
JILIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] At present, the cracking of lignin C-C bonds has the following problems: 1) the reaction conditions are harsh, requiring high temperature or high pressure; 4) product selectivity is poor, can produce multiple products

Method used

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  • Method for synthesizing nitrogen-containing aromatic compounds by one-step photocatalytic lignin depolymerization and amination
  • Method for synthesizing nitrogen-containing aromatic compounds by one-step photocatalytic lignin depolymerization and amination
  • Method for synthesizing nitrogen-containing aromatic compounds by one-step photocatalytic lignin depolymerization and amination

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] Example 1: Cleavage and Amination of Selective C-C Bonds of Lignin Dimer 1

[0028]

[0029] The reaction feed was carried out in a glove box, and lignin dimer 1 (0.1mmol, 24.4mg), photocatalyst cerium trichloride (1mol%), auxiliary agent tetrabutylammonium chloride (5mol%), azo Di-tert-butyl dicarboxylate (0.1 mmol) and 0.5 mL of acetonitrile were placed in a 10 mL reaction pressure tube. Seal the reaction pressure tube and place it under a blue light of 420nm, stir for 12 hours until the lignin dimer 1 is completely converted, and separate it by silica gel column chromatography (ethyl acetate:petroleum ether=1:5, volume ratio) to obtain The product p-methoxybenzaldehyde (12.4 mg, yield 91%) and 1-(phenoxymethyl)-1,2-dicarboxylate di-tert-butylcarboxylate-hydrazine (hydrazine 1) (30.8 mg, yield rate 91%).

[0030] NMR data:

[0031] p-Methoxybenzaldehyde: 1 H NMR (500MHz, Chloroform-d) δ9.87(s,1H),7.81–7.75(m,2H),7.01–6.95(m,2H),3.80(s,3H). 13 C NMR (126MHz, CD...

Embodiment 2

[0033] Cleavage and amination of selective C-C bond of embodiment 2 lignin dimer 2

[0034]

[0035] The reaction addition was carried out in a glove box, and lignin dimer 2 (0.1mmol, 27.4mg), photocatalyst di-n-tetrabutylcerium hexachloride [(nBu 4 N) 2 CeCl 6 ] (1mol%), auxiliary agent tetrabutylphosphorus chloride (5mol%), nitrogen source diisopropyl azodicarboxylate (0.1mmol) and 1.0mL dichloromethane in a 10ml pressure-resistant tube. Seal the reaction pressure tube and place it under ultraviolet 365nm, stir for 18 hours until the lignin dimer 2 is completely converted, and then separate it by silica gel column chromatography (ethyl acetate:petroleum ether=1:5, volume ratio) to obtain the product p-methoxybenzaldehyde (12.5 mg, yield 92%) and 1-(1-phenoxyethanolyl)-1,2-dicarboxylate diisopropyl-hydrazine (hydrazine 2) (20.4 mg, Yield 81%).

[0036] NMR data:

[0037] P-methoxybenzaldehyde: as in Example 1.

[0038] Hydrazine 2: 1H NMR (500MHz, Chloroform-d) δ7.3...

Embodiment 3

[0039] Cleavage and amination of selective C-C bond of embodiment 3 lignin dimer 3

[0040]

[0041] The reaction feed was carried out in a glove box, and lignin dimer 3 (0.1mmol, 33.4mg), photocatalyst cerium trifluoromethanesulfonate (5mol%), auxiliary agent tetrabutylammonium chloride (5mol%), Nitrogen source di-tert-butyl azodicarboxylate (1 mmol) and 2.0 mL pyridine in a 10 mL pressure-resistant tube. Seal the reaction pressure tube and place it under a purple lamp at 380nm, stir for 24 hours until the lignin dimer 3 is completely converted, and then separate it by silica gel column chromatography (ethyl acetate:petroleum ether=1:5, volume ratio) to obtain The products 3,4-dimethoxybenzaldehyde (13.4 mg, 81% yield) and 1-[1-(2-methoxy)phenoxyethanol]-1,2-dicarboxylic acid diisopropyl Esteryl-hydrazine (hydrazine 3) (28.3 mg, 71% yield).

[0042] NMR data:

[0043] 3,4-Trimethoxybenzaldehyde: 1 H NMR (500MHz, Chloroform-d) δ9.85(d, J=1.2Hz, 1H), 7.52–7.43(m, 2H), 7....

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Abstract

The invention relates to a method for synthesizing nitrogen-containing aromatic compounds by one-step photocatalytic lignin depolymerization and amination, belonging to the technical field of lignin application. The invention takes lignin or model compound thereof as a reaction substrate, dissolves the reaction substrate in a solvent, reacts at room temperature for 6-24 hours under the excitationof a light source and catalysis of a photocatalyst with the assistance of a promoter and a nitrogen source, and carries out C-C bond selective cleavage and amination to synthesize nitrogen-containingaromatic compounds; the molar ratio of lignin or model compound thereof, photocatalyst, promoter and nitrogen source is 100: (1-20): (1-100): 100. The invention has the advantages of simple reaction steps, mild reaction conditions, high bond breaking selectivity, high product selectivity, 100% atomic efficiency, environmental protection, selective cleavage and amination of C-C bond by one-step reaction, continuous feeding, good degradation of natural lignin, further reaction of hydrazine products to obtain nitrogen heterocyclic compounds and other advantages

Description

technical field [0001] The invention belongs to the technical field of lignin application, and specifically relates to a method for synthesizing nitrogen-containing aromatic compounds through one-step photocatalytic lignin depolymerization and amination. Background technique [0002] Petroleum is a non-renewable resource, and seeking sustainable petroleum substitutes is in line with the needs of sustainable development of contemporary society. Lignocellulose is the most abundant carbon-containing biomass on earth, and it is mainly composed of cellulose, hemicellulose and lignin. Among them, the reserve of lignin is second only to cellulose, it is the second most renewable biomass resource, and it is also the only non-fossil-based resource containing aryl groups in nature. However, lignin has not been widely used in large quantities so far, and most of it is discharged or burned as papermaking wastewater, which not only causes serious environmental pollution, but also wastes...

Claims

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Application Information

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IPC IPC(8): C07C45/51C07C47/575C07C47/54C07C281/02C07D229/00C07D273/04
CPCC07C45/512C07C47/54C07C47/575C07C281/02C07D229/00C07D273/04
Inventor 张越涛何江华王银玲
Owner JILIN UNIV
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