title: Theoretical design of multi-nitroxyl organocatalysts with enhanced reactivity for aerobic oxidation.
abstract: Higher catalytic performances of N,N',N''-trihydroxyisocyanuric acid (THICA), N,N-dihydroxypyromellitimide (NDHPI), and N-hydroxynaphthalimide (NHNI) than that of N-hydroxyphthalimide (NHPI) have been demonstrated recently in aerobic oxidation. Herein, the rational design of reactive multi-nitroxyl organocatalysts has been addressed theoretically by using systematic analysis of some important properties and catalytic activities of yet-to-be-synthesized catalysts. Our results show that 1) NHNI and its analogue, similar to THICA, unlike NHPI and others, are unsuitable for solvent- or mediator-free catalysis due to their strong intramolecular hydrogen-bonding interactions; 2) increasing the reactive hydroxyimide groups on the same aromatic ring, or doped N atoms or ionic-pair groups onto the aromatic ring, can improve catalytic reactivity, whereas appropriate enlargement of conjugated aromatic systems results in unchanged activity; 3) the newly designed catalysts are more active than NHPI and NHNI and have catalytic activities comparable to NDHPI and THICA; 4) the ionic-pair supported case is suggested to be a very active catalyst, even towards inert propane, and can be used as a novel model catalyst for further improvements. The present work will be helpful in designing reactive hydroxyimide organocatalysts.
authors.affiliation: Department of Chemistry, ZJU-NHU United R&D Center, Zhejiang University, Hangzhou 310027 (China); State Key Laboratory of Chemical Engineering, Department of Chemical and Biological Engineering, Zhejiang University, Hangzhou 310027 (China).
authors.forename: Kexian
authors.initials: K
authors.lastname: Chen
authors.forename: Lu
authors.initials: L
authors.lastname: Jia
authors.forename: Congmin
authors.initials: C
authors.lastname: Wang
authors.forename: Jia
authors.initials: J
authors.lastname: Yao
authors.forename: Zhirong
authors.initials: Z
authors.lastname: Chen
authors.forename: Haoran
authors.initials: H
authors.lastname: Li
keywords: density functional calculations; imides; nitrogen heterocycles; organocatalysis; oxidation