scholarly journals Aerobic Oxidation Reactivity of Well-Defined CoII and CoIII Aminophenol Complexes

Author(s):  
Jiaqi Liu ◽  
Brian Dolinar ◽  
Jessica Hoover

This article describes the synthesis and reactivity studies of three cobalt complexes bearing aminophenol-derived ligands without nitrogen substitution: CoII(tBu2APH)2(tBu2AP)2 (1), Co2III(tBu2APH)2(tBu2AP)2(μ-tBu2BAP)2 (2), and CoIII(tBu2AP)3 (3) (tBu2APH = 2-amino-4,6-di-tert-butylphenol, tBu2AP = 2-amino-4,6-di-tert-butylphenolate, μ-tBu2BAP = bridging 2-amido-4,6-di-tert-butylphenolate). Stoichiometric reactivity studies of these well-defined complexes demonstrate the catalytic com-petency of both CoII and CoIII complexes in the aerobic oxidative cyclization of tBu2APH with tert-butyl isonitrile. Reactions with O2 reveal the aerobic oxidation of CoII complex 1 to generate the CoIII species 2 and 3. UV-visible time-course studies and EPR spectroscopy indicate that this oxidation proceeds through a ligand-based radical intermediate. These studies repre-sent the first example of well-defined cobalt-aminophenol complexes that participate in catalytic aerobic oxidation reactions and highlight a key role for a ligand radical in the oxidation sequence.

2018 ◽  
Author(s):  
Asim Maity ◽  
Sung-Min Hyun ◽  
Alan Wortman ◽  
David Powers

<p>Hypervalent iodine(V) reagents, such as Dess-Martin periodinane (DMP) and 2-iodoxybenzoic acid (IBX), are broadly useful oxidants in chemical synthesis. Development of strategies to access these reagents from O2 would immediately enable use of O2 as a terminal oxidant in a broad array of substrate oxidation reactions. Recently we disclosed the aerobic synthesis of I(III) reagents by intercepting reactive oxidants generated during aldehyde autoxidation. Here, we couple aerobic oxidation of iodobenzenes with disproportionation of the initially generated I(III) compounds to generate I(V) reagents. The aerobically generated I(V) reagents exhibit substrate oxidation chemistry analogous to that of DMP. Further, the developed aerobic generation of I(V) has enabled the first application of I(V) intermediates in aerobic oxidation catalysis.</p>


Author(s):  
LiXin Chen ◽  
Zi Wen ◽  
Zhi Wen Chen ◽  
Qing Jiang ◽  
Chandra Veer Singh

The activation mechanism of O2 molecules plays a vital role in the development of catalysts for aerobic oxidation reactions. To gain insights into the activation mechanism of O2, the square...


Catalysts ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 95
Author(s):  
Amarajothi Dhakshinamoorthy ◽  
Eva Montero Lanzuela ◽  
Sergio Navalon ◽  
Hermenegildo Garcia

Metal organic frameworks (MOFs) are porous crystalline solids whose frameworks are constituted by metal ions/nodes with rigid organic linkers leading to the formation of materials having high surface area and pore volume. One of the unique features of MOFs is the presence of coordinatively unsaturated metal sites in their crystalline lattice that can act as Lewis acid sites promoting organic transformations, including aerobic oxidation reactions of various substrates such as hydrocarbons, alcohols, and sulfides. This review article summarizes the existing Co-based MOFs for oxidation reactions organized according to the nature of substrates like hydrocarbon, alcohol, olefin, and water. Both aerobic conditions and peroxide oxidants are discussed. Emphasis is placed on comparing the advantages of using MOFs as solid catalysts with respect to homogeneous salts in terms of product selectivity and long-term stability. The final section provides our view on future developments in this field.


2017 ◽  
Vol 75 (1) ◽  
pp. 80 ◽  
Author(s):  
Wen-Qiang Zhang ◽  
Qiu-Yan Li ◽  
Xinyu Yang ◽  
Zheng Ma ◽  
Huanhuan Wang ◽  
...  

2021 ◽  
Vol 43 (2) ◽  
pp. 193-193
Author(s):  
Taiping Gao Taiping Gao ◽  
Xiaolin Ma Xiaolin Ma ◽  
Xin Li Xin Li ◽  
Qiang Xu and Yubao Wang Qiang Xu and Yubao Wang

The first mesoporous silica nanoparticles (MSNs) supported atomically precise palladium nanoclusters catalyzed alcohol oxidation reactions in water have been achieved. The catalysts was synthesized with simple impregnation method and well characterized by TEM, FT-IR, XPS anddiffuse reflectance optical spectrum and the results proved that the Pd nanoclustersimmobilized into the pores of MSNs.The as-prepared catalyst show excellent activity for the alcohol oxidation reactions with high yield under extremely mild aqueous conditions utilizes 1 atmosphere of molecular oxygen as sole oxidant. The features of clean system, gram-scale oxidation and easy recovery catalyst make this method cost effectively and environmentally benign.


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