聚苯醚合成中配体对催化剂活性与稳定性影响
Ligand effects on catalyst activity and stability for polyphenylene oxide (PPO) polymerization
在聚苯醚(PPO)的合成中,不同的胺与Cu离子形成的配合物对氧化偶联反应产物的收率具有显著影响。通过密度泛函理论(DFT)计算结合实验,深入探究了不同胺类配体[四甲基乙二胺(TEMED)、二丙胺(DPA)、N,N-二甲基丙胺(MSDS)]对Cu配合物催化剂性能的影响机制。DFT计算结果表明,MSDS配位的Cu配合物在氧化偶联反应中表现出显著优势,其电子转移过程和亲核进攻过程中的反应能垒最低,然而其催化收率(8.31%)远低于配体TEMED(94.56%)和DPA(80.94%)。对Cu配合物进行刚性扫描发现,MSDS配位下,配合物的稳定性最差,这增加了反应中间体的解离风险。相比之下双齿配体TEMED可以有效限制Cu离子的空间运动,显著提高配合物的稳定性,增强催化活性并降低反应中间体的解离风险,这一发现为优化PPO合成中催化剂的设计与选择提供了重要理论依据。
In the synthesis of polyphenylene oxide (PPO),complexes formed by different amines and Cu ions have a significant impact on the yield of products in the oxidative coupling reaction.In this study,density functional theory (DFT) calculations combined with experiments were employed to deeply explore the influence mechanism of different amine ligands (tetramethylethylenediamine/TEMED,dipropylamine/DPA,N,N-dimethylpropylamine/MSDS) on the performance of Cu complex catalysts.The results of DFT calculations indicate that the Cu complex coordinated by MSDS shows remarkable advantages in the oxidative coupling reaction,with the lowest reaction energy barriers in the single-electron transfer process and the nucleophilic attack process.However,its catalytic yield (8.31%) is much lower than those of the ligands TEMED (94.56%) and DPA (80.94%).Through a rigid scan of the Cu complexes,it was found that under the coordination of MSDS,the complex has the worst stability,which increases the dissociation risk of reaction intermediates.In contrast,the bidentate ligand TEMED can effectively restrict the spatial movement of Cu ions,significantly improve the stability of the complex,enhance catalytic activity,and reduce the dissociation risk of reaction intermediates.This finding provides an important theoretical basis for optimizing the design and selection of catalysts in the synthesis of PPO.
polyphenylene oxide / amine ligand / Cu ion complex
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