Preparation And Catalysis Oxidation Property Of Supported Manganoporphyrin Based On Poly(Glyceryl Methacrylate)

Metalloporphyrins biomimetic catalyst have been used to oxidate hydrocarbonswith molecular oxygen,this is one of the most important domain of catalysis chemistryand organic chemistry at present.In this paper,a novel immobilized manganoporphyrincatalyzer was gained based on the polymeric support PGMA/SiO₂.The heterogeneouscatalyst was used in the catalytic oxidation of ethyl benzene with molecular oxygenunder ordinary pressure as oxidant,and some valuable research results were found.Firstly,meso-5,10,15,20-tetra(4-hydroxylphenyl)porphyrin (THPP) was synthesizedby improved Adler's method.The chemical structure of the product was confirmed bythe spectra of FTIR,UV/Vis and ¹H NMR.The effects of reaction time,the addedamount of dimethyl sulfoxide(DMSO) and the used amount of propionic acid on theyield of THPP were examined.It was found that some DMSO could enhance the yield ofTHPP effectively and inhibit the side reaction.Besides,the reaction time and the usedamount of propionic acid also should be appropriate.Under the optimal condition,theyield of THPP can get up to 35%,furthermore,the crude product was purer,so thatbrilliant violet fine product could be obtained by using recrystallization method andcolumn chromatography method was not needed.The bonding reaction between poly (glyceryl methacrylate) (PGMA) and THPPwas carried out in a homogeneous system,and line-type porphyrin-functionalizedPGMA (denoted as HPP-PGMA) was obtained.Further,the coordination reactionbetween HPP-PGMA and Mn(â…¡) was performed and manganoporphyrin-functionalizedPGMA was gained (denoted as MnP-PGMA).The structure of HPP-PGMA wascharacterized by ¹H NMR spectrum.The electronic absorption and fluorescence emission spectra of HPP-PGMA and MnP-PGMA were determined and theirphotophysical behaviors were examined.The experimental results show that,line-typeHPP-PGMA and MnP-PGMA were prepared successfully by controlling the amount ofcatalyst NaHCO₃ and the reaction time.HPP-PGMA possesses the same characteristicelectronic absorption spectrum and fluorescence emission as porphyrins,the spectrumintensity of HPP-PGMA strengthens with the increase of the bound amount of HPP.MnP-PGMA has the same characteristic electron absorption spectrum as ordinarymanganoporphyrin.PGMA was bounded to silica by adopting the"Grafting from" method.THPP wasbound to the surface of PGMA/SiO₂ via the epoxy bond reacting to the hydroxyl andformed HPP-PGMA/SiO₂,Further,the coordination between HPP-PGMA/SiO₂ andMn(â…¡) was performed and PGMA/SiO₂ bound manganese porphyrin was gained(denoted as MnP-PGMA/SiO₂).FTIR spectrum of HPP-PGMA /SiO₂ was measured andits structure was characterized.The amount of Mn within MnP-PGMA/SiO₂ isdetermined by the atom absorbing spectra.The solid catalyst MnP-PGMA/SiO₂ can make dioxygen to be activated effectively,and obviously catalyze the transform of ethyl benzene into acetophenone.The catalystexhibits fine catalysis activity and selectivity,the yield of acetophenone at ordinarypressure of oxygen and 95℃in 12h can get up to 18%,and the content of anotherproduct,a-methyl benzoic alcohol,is very small.Some rules were specially found in thestudy:MnP as a biomimetic catalyst has an optimum used amount,and excess additionwill inhibit the catalyst activity;the smaller the immobilization density of MnP on thesurface of the grafting particle PGMA/SiO₂,the higher the catalyst activity is;thecatalyst activity trend to increase during the reuse of limited cycles.