Synthesis Of Non-heme Manganese Complexes With N4 Ligands And Their Application In Catalytic Oxidation Of Primary Alcohols

Inspired by the mild,efficient and highly selective characteristic of enzyme-catalyzed oxidation,the construction of biomimetic catalytic oxidation by simulating enzymes has become a hot research topic.Starting from the chemical simulation of the metal active sites of enzymes,a large number of biomimetic organic small molecule ligands and their metal complexes have been designed and synthesized.The metal complexes with N4 ligands based on the active center structure of non-heme enzymes are considered to be the model compounds simulating natural non-heme enzymes,which are mainly used in a series of oxidation reactions,such as epoxidation of olefins,dihydroxylation and C-H bond oxidation.However,there are few reports on the selective oxidation of alcohols catalyzed by metal complexes with N4 ligands.Organic carboxylic acids as cocatalyst are often used in most reported systems,and the dosage is even up to 14 equivalent.Then neutralization is needed at the end of the reaction,easily leading to large amounts of waste and pollution.The selective oxidation of alcohols is an important and widely used reaction in organic synthesis.Therefore,it is urgent to develop a novel,green and highly efficient nonheme mimic enzyme system to realize the selective oxidation of alcohols.Based on this,non-heme Manganese complexe with tetra-nitrogen ligands were synthesized and applized as the catalysts for selective oxidation of primary alcohols to corresponding aldehydes or acids employing,tetrabutyl ammonium bisulfate as the additive.The dissertation mainly focused on the following contents:1.Two kinds of tetranitrogen ligands MCP[N~1,N~2-dimethyl-N~1,N~2-bis(pyridin-2-ylmethyl)cyclohexane-1,2-diamine]and PMCP[N~1,N~2-dimethyl-N~1,N~2-bis(phenyl(pyridin-2-yl)methyl)cyclohexane-1,2-diamie]with different steric hindrances were synthesized through condensation,Grignard reaction and methylation,and coordinated with corresponding iron salts or manganese salts to prepare corresponding Iron/Manganese complexes with N4 ligand.The tetra-nitrogen ligands and their metal complexes were characterized by NMR,IR and HRMS.2.A novel biomimetic catalytic system for the selective oxidation of primary alcohols with H₂O₂ as oxidant was constructed by using the prepared non-heme Manganese complexs as the catalysts and tetrabutylammonium hydrogen sulfate as the co-catalyst.The results showed that(PMCP)Mn(OTf)₂ exhibited highest catalytic activity.94.2%The yield of benzaldehyde was 94.2%under the conditions of 0.5 mol%(PMCP)Mn(OTf)₂,1 mol%Bu₄NHSO₄,2 equivalent H₂O₂ at room temperature for 1 h.Employing 1 mol%(PMCP)Mn(OTf)₂ as the catalyst and 3 mol%Bu₄NHSO₄ as the co-catalyst,benzoic acid was selectively obtained in 89.5%yield by using 3 equivalent H₂O₂ for 4 h at room temperature.This system has a wide range of substrates and could be used for the oxidation of aromatic,aliphatic,heteroatomic and series of primary alcohols with different functional groups,and corresponding aldehydes or acids could be obtained with more than 80%selectivity.