| Much attention has been paid in the synthesis of Metal-Salen[N,N-bis-(saliylaldehyde)ethylen-diamine]complexes as its similar characteristics in terms of sterically hindrance,the electronic structure and catalytic activity with the active portion of metal porphyrin complexes in the cytochrome P450,and its application in ring-opening of epoxides,Diels-Alder reaction,hydrolytic kinetic resolution of racemic epoxides,oxidation of sulfides,epoxidation of unfunctionalized alkenes,as well as cycloaddition or copolymerization of CO2 and epoxides.Compare to P450,Metal-Salen complexes have many advantages such as structure diversity,easy to prepare and low cost.In this thesis,Mn(?)-Salen(N-N)catalyst with an anchored functional group of pyridine was synthesized and applied to the epoxidation of unfunctionalized alkenes and cycloaddition of CO2 with propylene epoxide.The results show that Mn(?)-Salen(N-N)catalyst could catalyze both types of reactions in high catalytic activity and selectivity(1)Multi-coordination points of pyridine functional group was synthesized with 2-tert-butylphenol,pyridine-4-boronic acid and diamine as the starting materials followed by the Formylation,Suzuki-Coupling,Schiff-Base and other reactions.Its molecular structure was determined by X-ray single crystal diffractometor.Mn(?)-Salen(N-N)catalyst was prepared by the oxidation of Mn(?)-Salen(N-N)complex which was synthesized through the reaction of Salen(N-N)ligandwith Mn(OAc)2.The Mn(?)-Salen(N-N)complex was characterized by FT-IR,ESI-MS and Elementary Analysis.The structure analysis show that the Mn(?)ions wascoordinated in the center of Salen(N-N)ligand with two nitrogen atoms and two oxygen atomsfrom phenolpart,and the counter ion is Cl-.(2)Mn(?)-Salen(N-N)complex was used as catalyst for epoxidation of the styrene.First,eight different oxidation systems were studied and(diacetoxyiodo)benzene[PhI(OAc)2],4-Methyl-morpholine N-oxide(NMO)system showed the best catalytic performance.Furthermore,the effection of solvents,quantity of catalyst,the types of axial ligand and reaction temperature on oxidation of styrene was studied.The results show that 2 equiv.(relative molar amounts of styrene)PhI(OAc)2,5 mL acetone,0.03 equiv.Mn(?)-Salen(N-N)and 0.3 equiv.NMO stirred at 30? for 4 h,give 99%of the conversion of styrene with 99%of the selectivity of styrene oxide.In addition,H2O2 as its low cost,environmentally benign and high oxygen contents was chosen as oxidant for epoxidation of the styrene.It was found that the best conversion of styrene can up to 96%with 87%yield of styrene oxide,under the condition of 0 ? with 6 equiv.H2O2,8 mL methanol,0.06 equiv.Mn(?)-Salen(N-N)and 0.3 equiv.1,2-dimethyl-axial ligand imidazole(DMIm)stir for 7 h.The results also showed higher yield of epoxides for epoxidation of nonterminal olefins using H2O2 oxidation can be obtained compare to PhI(OAc)2 systerm.(3)the catalytic properties of Mn(III)-Salen(N-N)catalystfor the cycloaddition of CO2 with propylene epoxide(PO)was studied in the condition of without solvent.Influence of quantityof catalyst,temperature,pressure and reaction time was investigated.the result showed 96%of the conversion of PO with 94%of the selectivity of propylene carbonate(PC)were obtained under the condation of 0.25 mol%(relative molar amounts of PO)of catalyst concentration,stir at 60?,3 MPa for 6 h,.Furthermore,this study confirmed that the cycloaddition of CO2 and epoxides must be accomplished.by the intramolecular cooperation of this binary catalyst system,which containing Mn(?)-Salen(N-N)complex woked as the electrophile part and tetrabutylammonium bromide(TBAB)worked as the nucleophile part.In summary,Mn(III)-Salen(N-N)catalyst with the multi-coordination points of pyridine functional group was designed and synthesized.this complex can catalyze the epoxidation of olefins and the cycloaddition of CO2 and epoxides with high activity and selectivity.These results give the great opportunity of one-pot synthesis of cyclic carbonate directly from olefins and CO2. |
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