سنتز نانو کاتالیست های ابرپارامغناطیسی γ-Fe2O3 اندود شده با هیدروکسی آپاتیت های عامل دار و کاربرد آنها در واکنشهای آلی

Today, for the goals of green chemistry, magnetic nanoparticles open up new avenue to introduce an efficient system for facilitating catalyst recovery in organic reactions. Because of the sensitivity of the magnetic nanoparticles and strong surface affinity towards hydroxyapatite, these nanoparticles can be coated with hydroxyapatite. Hydroxyapatite, the main component of bone and teeth, is of considerable interest in many areas because of ion-exchange ability, adsorption capacity and acid–base properties. Herein we utilize the adsorption capacity of HAp and deposit some metals(such as Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+) in the surface of γ-Fe2O3@HAp to preparing new and green Lewis acid catalysts (γ-Fe2O3@HAp-M2+). These magnetic nanoparticles were characterized by SEM, VSM, XRD, FT-IR and EDX techniques. Loading of transition metals were calculated by EDX spectroscopy. Then, the catalytic activity of them was compared in organic reaction. The magnetic supported metals show high activities in aminolysis of epoxides. The best catalytic activity was observed with the superparamagnetic γ-Fe2O3@HAp-Fe+2. In addition, reusing of catalyst was done successfully in subsequent runs without any decrease in activity even after 5 runs; also no leaching of transition metal was observed in the reaction medium for γ-Fe2O3@HAp-Fe+2. Easy separation and recyclability is most important advantages of these catalysts to other heterogeneous and homogeneous Lewis acid catalysts