Synthesis And Catalytic Performance Of New Metal-salen Complexes

Due to the structural variability,conjugation and multivalent states of the metal ions,metal-Salen complexes are usually applied in the organic reactions as the catalysts and also in the electrochemistry as the electrode materials.In this work,salicylaldehyde as the initial reactant,two Salen ligands and corresponding metal-Salen complexes were synthesized according to the Friedel-Crafts acylation and Claisen rearrangement.And these as-prepared complexes were applied in the electrochemistry,the oxidation of hydroquinone with hydroperoxide and the epoxidation of the olefin.The main work is as follows:???On the basis of the Friedel-Crafts acylation and Claisen rearrangement,two Salen ligands,bis?3-hydroxy-4-aldehyde benzoylbenzene?tetramethylene diamine?a?and bis?3-allyl salicylaldehyde?tetramethylene diamine?b?,were synthesized.Then the two Salen ligands coordinated with copper ions to form metal-Salen complex a and b respectively.The structure of these two complexes were characterized by the X-ray single crystal diffraction.In addition,because C=C in the Salen ligand b is reactive,Salen ligand b first coordinated with manganese ions to form a metal-Salen complex and then C=C in the complex further reacted to form epoxy bond,which metal-Salen complex c was prepared.???The catalysis of metal-Salen complex a and c for the epoxidation of styrene,1-octene and soybean oil was studied.The effect of the temperature,reaction time,catalyst dosage and oxygen-to-substrate molar ratio on the reaction were discussed.These two complexes all exhibited good catalytic capacity on the epoxidation.The catalysis effect of the same complex was in sequence of 1-octene>styrene>soybean oil.For the same substrate,metal-Salen complex c had better catalytic effect than metal-Salen complex a.Under the optimal conditions and Salen complex c as the catalyst,the conversion rate of styrene was 51.0%and the selectivity was 64.0%;the conversion rate of 1-octene was 58.8%and the selectivity was69.6%;the conversion rate of soybean oil was 33.0%and the selectivity was 51.0%.???The catalysis of metal-Salen complex a for the oxidation of hydroquinone?HQ?with hydroperoxide was studied by the UV-Vis spectroscopy.The effect of reaction temperature,pH values and H₂O₂-to-complex concentration ratios was discussed.When the temperature was 37.5?,the pH value was 7.0,and the H₂O₂-to-complex concentration ratio was 70,the complex had the best catalytic effect.???The metal-Salen complex a and b was employed as a modifier to modify the glassycarbon electrode?M-Salen-a/GCEandM-Salen-b/GCE?.The electrocatalytical properties of the modified electrodes for the electrochemical reaction of HQ and H₂O₂ were investigated by cyclic voltammetry and chronoamperometry.Under the optimal conditions,the two modified electrodes all exhibited the excellent electrocatalytical perfomance with the wider range of the detected concentration and the higher sensitivity.For thedetcetion of H₂O₂,the linear ranges at these two modified electrodes were 0.1¹807?M.For the detcetion of HQ,the linear ranges were 0.05²261?M at M-Salen-a/GCE and 0.05¹708?M at M-Salen-b/GCE.