Theoretical studies on muti-hydroxyimides as highly efficient catalysts for aerobic oxidation.
Theoretical studies on muti-hydroxyimides as highly efficient catalysts for aerobic oxidation.
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DOI：
10.1002/cphc.201200865
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发表时间：
2013-01
期刊：
影响因子：
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通讯作者：
Kexian Chen;Lu Jia;Rina Dao;Jia Yao;Congmin Wang;Zhi-rong Chen;Haoran Li
中科院分区：
文献类型：
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作者：
Kexian Chen;Lu Jia;Rina Dao;Jia Yao;Congmin Wang;Zhi-rong Chen;Haoran Li
N，N-二羟基均苯二甲酰亚胺（NDHPI）和N，N '，N“-三羟基异氰脲酸（THICA）最近被证明比流行的N-羟基邻苯二甲酰亚胺（NHPI）作为更好的碳自由基产生催化剂。为了更好地理解这些特殊的催化剂，本文通过理论分析，系统地研究了它们的几何、电子和热化学性质，以及它们的催化活性。与NDHPI和NHPI不同的是，THICA由于其有利的共存平面构象而不适用于无溶剂催化或非质子溶剂中的催化。此外，NDHPI和THICA的催化效率高于NHPI，这是由于它们的自由基，特别是多自由基具有较强的吸电子效应，在吸氢过程中具有较低的能垒和吸热性。此外，THICA自由基的产生在高温下没有助催化剂是非常可行的。该研究为合理设计反应性羟基酰亚胺有机催化剂提供了一个新的视角。
N,N-dihydroxypyromellitimide (NDHPI) and N,N',N''-trihydroxyisocyanuric acid (THICA) have been recently demonstrated to act as better carbon-radical-producing catalysts than the popular N-hydroxyphthalimide (NHPI). To gain a mature understanding of these particular catalysts, herein their geometrical, electronic, and thermochemical properties, as well as their catalytic activities, have been systemically investigated by a theoretical analysis. It appears that THICA, unlike NDHPI and NHPI, is unsuitable for solvent-free catalysis or catalysis in aprotic solvents due to its favorable coexistent planar conformer. Besides, the more remarkable catalytic efficiencies of NDHPI and THICA compared to NHPI can be ascribed to the lower barriers and the endothermicity in the H-abstraction processes by their radicals, especially by their multi-radicals which show stronger electron-withdrawing effects. Furthermore, the generation of THICA radicals would be much feasible at high temperature without co-catalysts. This study provides a new perspective towards the rational design of reactive hydroxyimide organocatalysts for industrial applications.