Photocatalytic promotion of benzylamine C-N coupling by oxygen vacancies in bismuth oxychloride@nanocellulose composites
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摘要: 本工作采用纳米纤维素(CNC)为载体,与BiOCl在室温搅拌下制备了复合光催化剂BiOCl@CNC。XRD、FT-IR、SEM、TEM、XPS等系列表征表明,CNC中大量羟基可以与BiOCl通过氢键紧密结合,并在材料中构造丰富的氧空位,从而显著提升其可见光催化性能。以可见光下催化苄胺C−N偶联为目标反应评估BiOCl@CNC的性能并对机理进行研究。首先对反应条件进行优化,得最优条件为1.0 mmol苄胺作为底物,20 mg BiOCl@CNC作催化剂,以30 W 白色LED灯为光源,在CH3CN中氧气氛围下室温反应20 h。底物扩展实验表明,BiOCl@CNC对含有不同取代基的反应物均表现出良好的适应性,且具有优异的稳定性。通过自由基捕获实验表明,电子在氧空位的辅助下产生超氧自由基,并与胺阳离子自由基中间体形成最终产物。这一工作不仅丰富了Bi基复合半导体的应用,也为N-苄烯丁胺的合成提供了新思路。Abstract: In this study, a composite photocatalyst BiOCl@CNC was prepared by simple stirring with BiOCl at room temperature using nanocellulose (CNC) as a carrier. Comprehensive characterizations (XRD, FT-IR, SEM, TEM, XPS) reveal that the abundant hydroxyl groups in CNC can form strong hydrogen bonds with BiOCl, leading to the creation of numerous oxygen vacancies in the material and thereby significantly enhancing its visible light-driven photocatalytic performance. The performance of the BiOCl@CNC was evaluated using the C-N coupling reaction of benzylamine as the target reaction under visible light, and the underlying mechanism was investigated. The results show that the optimal reaction process is that 1.0 mmol of benzylamine and 20 mg of BiOCl@CNC are added to CH3CN under an oxygen atmosphere to react for 20 hours using a 30 W white LED lamp as the light source. In the substrate expansion experiments, the BiOCl@CNC exhibits remarkable adaptability and exceptional stability towards reactants with diverse substituents. The free radical capture experiments demonstrate that the electrons can effectively generate superoxide radicals in the presence of oxygen vacancies and subsequently form the ultimate product through amine cation radical intermediates. This study not only expands the application potential of Bi-based composite semiconductors but also presents novel insights for synthesizing N-benzylene butylamine.
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Key words:
- BiOCl /
- nanocellulose /
- oxygen vacancy /
- visible light catalysis /
- oxidation of benzylamine
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表 1 反应条件的优化
Table 1 Optimization of reaction conditions
Entrya Cat. Solvent Light source Conv./%b 1 − CH3CN White LED 4 2 CNC CH3CN White LED 6 3 BiOCl CH3CN White LED 73 4 BiOCl@CNC CH3CN White LED 99 5c BiOCl@CNC CH3CN White LED 87 6d BiOCl@CNC CH3CN White LED 98 7 BiOCl@CNC (10 mg) CH3CN White LED 22 8 BiOC@CNC (15 mg) CH3CN White LED 91 9 BiOCl@CNC (25 mg) CH3CN White LED 97 10 BiOCl@CNC CH3CN Red LED 2 11 BiOCl@CNC CH3CN Blue LED 94 12 BiOCl@CNC CH3CN Green LED 7 13 BiOCl@CNC THF White LED 20 14 BiOCl@CNC DMSO White LED 10 15 BiOCl@CNC DMAc White LED 35 16 BiOCl@CNC C2H5OH White LED 8 17 BiOCl@CNC CH3CN/H2O White LED 16 a: Reanction conditions:benzylamine (0.1 mmol), catalyst (20 mg), slovent (4.0 mL), the reaction time was 20 h; b: The conversion rate was determined by the GC; c,d: The reaction time were 15 and 25 h, respectively. 表 2 反应底物适应性研究
Table 2 Substrate suitability studies
Entrya Substrates Products Conv./%b Sel./% 1 99 ≥99 2 88 98 3 90 ≥99 4 95 ≥99 5 90 ≥99 6 85 ≥99 7 94 98 8 66 ≥99 9 43 ≥99 10 81 ≥99 a: Reaction conditions:benzylamines (0.1 mmol), BiOCl@CNC (20 mg), CH3CN (4.0 mL); b: The conversion rate was determined by the GC. -
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