Studies On The Clean Oxidation Of Anethole Using Novel Iron-based Catalysts

Nanoscale metal-organic frameworks(NMOFs)have emerged as a promising platform for heterogeneous catalysis owing to higher specific surface area,more catalytic centers and facile modification.Also of considerable interest,iron is intriguing for the design of novel Fe-MOF catalysts because of its advantages such as cheapness,nontoxicity and excellent catalytic properties.Therefore,much attention has been paid on the research of Fe-based NMOFs used as biomimetic catalysts.Ionic liquid(IL)is a new type of green material,which can be used as green medium,catalyst or ligand.It is widely used in the field of organic synthesis.Imidazole-based ionic liquid containing anion or nitrogen atom can change the catalytic properties of metal center,thus improving the catalytic efficiency of the related system.02>TBHP(tert-butyl hydroperoxide)and H2O2 are common clean oxygen sources.Meanwhile,TBHP and H2O2 have high reactive oxygen content.Herein,using molecular oxygen,TBHP or H2O2 as the oxidant,series of novel and highly efficient catalysts such as nanoscale Fe-MOFs and iron-based Lewis acidic ionic liquids were explored for the catalytic oxidation of anethole.Good results were obtained and the main contents of the thesis are summarized in the following:1.A series of nanoscale Fe-MOFs were conveniently prepared via hydrothermal method and characterized by XRD,FT-IR,TG and TEM,respectively.The effects of catalyst,solvent type and reaction time on the oxidation of anethole to anisaldehyde with O2 were investigated systematically.The results showed that using Fe(PMA)(PMA:pyromellitate)as catalyst,O2 as oxidant and ethyl acetoacetate as medium,59.5%yield for anisaldehyde can be achieved after 12 h reaction at 60?.Additionally,Fe(PMA)catalyst can be reused for 4 times without an apparent degradation in catalytic activity,implying good reusability.2.Using Fe-MOFs as catalyst,70%TBHP as oxidant and ionic liquid as additive,oxidation of anethole to 4-methoxyphenylacetone through tandem transformation was explored.The effects of catalyst,ionic liquid and reaction time on the oxidation of anethole were investigated systematically.The results showed that the[C4min][Cys]/Fe(PMA)/TBHP nanosystem can act as a good redox-Lewis acid bifunctional catalyst.Under the optimized conditions(12 h at 50?),99.7%conversion of anethole and 85.5%selectivity for 4-methoxyphenylacetone were obtained with Fe(PMA)/TBHP nanosystem when using 5.0 mol%[C4mim][Cys]as the additive.Additionally,the yield of 4-methoxyphenylacetone was up to 84%even after 10 cycles.TEM,XRD,FT-IR,RDUV-vis and UV-vis analyses showed that Fe(PMA)/[C4min][Cys]could form a synergistic nano-system in situ to improve the reactivity and reusability performances of Fe(PMA).3.Prefabricated iron-based IL catalysts and IL-FeCl3·6H2O were examined for the anethole conversion.The optimum reaction conditions were as follows:(1)using in-situ prepared FeCl3·6H2O-[C4mim][HSO4](n([C4mim][HSO4])/n(FeCl3·6H2O)=1:2)(mole ratio))as catalyst,H2O2 as oxidant,the yield and selectivity of anisaldehyde were 65.1%and 80.6%after 3 h reaction at 25?.(2)using[C12mim]Cl-FeCl3 as catalyst,acetonitrile as solvent,H2O2 as oxidant,the yield and selectivity of anisaldehyde were 72.5%and 82.8%after 3 h reaction at 25?.