Investigation Into The Catalytic Aerobic Oxidation Of Alcohols Under Mild Conditions

Enzymes widely exist in the organism,and they can effectively catalyze various biochemical reactions and promote the metabolism of the organism.Study of their structure and mechanism is helpful to develop efficient biological inorganic catalysts.The mainly study of our work focus on the mimics of the structure and function of galactose oxidase and divided into two parts.Firstly,we have designed and synthesized novel multi-dentate ligands according to the center activity structure of galactose oxidase,[Cu(HL1)(OAc)(HOAc)](1),[Cu(HL2)(OAc)](2),[Cu(HL3)(OAc)](3),[CuL4(OAc)](4),[Cu2(L1)2](5),[Cu2(L3)2](6),[Cu(H1L2)Cl](7),[Cu(HL3)Cl](8),Related compounds were characterized using UV–vis spectroscopy,high resolution mass spectrum,X-ray single crystal diffraction analysis and electrochemistry.These copper(II)complexes have been investigated as catalysts for the aerobic oxidation of benzyl alcohol to benzaldehyde in water under ambient temperature.Mechanistic investigations revealed that the phenolate/phenol involved intramolecular proton transfer with bound substrate in catalysis and hence the presence of trifluomethyl group on the phenol ring affects significantly the catalysis since the substituent affects the acidity of the phenol and then the intramolecular proton transfer from the bound substrate.In the catalysis,the dissociation of the auxiliary ligand(Cl-or OAc-)occurred in SN1 pathway and it is necessary for the substrate to bind.To complete the catalytic cycle,the cleaved auxiliary ligand rebinds to the metal centre to regenerate the catalyst.Secondly,we have studyed a simple catalytic system with TMEDA(N,N,N’,N’-Tetramethylethylenediamine)/CuI/TEMPO(2,2,6,6-tetramethylpiperidinyl-1-oxyl),which enables efficient and selective aerobic oxidation of various alcohols including primary and secondary benzylic,allylic,and aliphatic alcohols to their corresponding aldehydes and ketones at room temperature with ambient air as the oxidant.The catalytic effect is strongly related to the saturation of the metal center.When the coordination of the metal center is unsaturated,it is beneficial to the coordination of the alcohol to the metal and demonstrates good catalytic efficiency.Otherwise,the catalysts show poor activities.