One-pot Preparation Of Proline-magnetic Nanocatalysts For Heterogeneous Transamidation Of Carboxamides With Amines

As one of the most basic and important magnetic materials,Fe₃O₄ has attracted much attention in recent years because ofits wide-ranging applications for electronic devices, catalysis,biomedical utilizations, drug delivery, enzyme immobilizationand so on. Combined with its self-advantages, Fe₃O₄ nanoparticles possess special properties（for example: environmental friendliness, good biocompatibility, high dispersity, easily separated by external magnetic field） as supports for catalyst supporting. Among the various methods for preparation of magnetic Fe₃O₄ nanoparticles, solvothermal is one of the most widely applied strategies, which could be utilized to prepare Fe₃O₄ nanoparticles with the properties of morphology and size-control, mono-dispersity and high quality. The aim of this dissertation is to find an approach to combine supporting catalysts and preparation of nanomaterials together, which is to say, a one-step way to obtain magnetic nanoparticles with supported organocatalysts through solvothermal method was expected.In this dissertation, on the basis of a scientific review of properties, preparation methods and applications of magnetic nanoparticles, as well as the research status of the supported catalysts, we imagined to prepare magnetic Fe₃O₄ nanoparticles directly modified by L-proline（or its derivates） through a “one-pot” solvothermal method. And, the functional magnetic Fe₃O₄ nanoparticles were utilized as the catalysts for transamidation of carboxamideswith amines. The main contents of this dissertation are shown as follows:1. One-potpreparation of L-4-OH-proline modified multi-functional Fe₃O₄ nanoparticles as catalysts forheterogeneous transamidation of carboxamideswith amines.In this section, magnetic Fe₃O₄ nanoparticles directly modified by L-4-OH-proline, which were marked as Fe₃O₄@OH-Pro, were prepared in one step by the solvothermal method. The influences of the concentration of L-4-OH-proline on the morphology and size of the nanoparticles were investigated and, the Fe₃O₄@OH-Pro nanoparticles were applied as supported nanocatalyst for transamidation of carboxamideswith amines under the optimal conditions. The morphology and construction of the particles were measured by TEM, SEM, FT-IR, TG, XRD, EDX mapping, element analysis. The Fe₃O₄@OH-Pro nanoparticles acted out good activity for catalyzing the reaction, and the nanocatalysts can be used at least 5 times, after which it still maintained good catalytic activity. In the process of preparation of Fe₃O₄@OH-Pro nanoparticles, L-4-OH-proline played multiple roles: surfactant, linker and catalytic group. Our investigation provided a simple and green method to prepare supported catalyst, which has promising values of researches and applications.2. One-pot preparation of catechol-like L-proline derivative modified Fe₃O₄ nanoparticles as high effiency catalysts forheterogeneous transamidation of carboxamideswith amines under neat condition.Based on the previous experiment, this part focused on how to increase the catalyst loading and enhance the connection strength between the catalyst and the supports while preparing the functional nanoparticles in a one step method. To begin with, we synthesized the L-proline derivative:（S）-N-（3,4-dihydroxyphenethyl）pyrrolidine-2-carboxamide（DA-Pro）, because of the catechol-like construction of DA-Pro, it was provided with strong coordination ability to Fe3+. So the DA-Pro was added in the reaction system while the magnetic supported catalysts were prepared by a solvothermal method as a multiple functional reagent, the nanocatalysts we prepared were marked as Fe₃O₄@DA-Pro. The morphology and construction of Fe₃O₄@DA-Pro nanoparticles were measured by TEM, FT-IR, TG, XRD, and element analysis, while the catalytic property of the nanocatalyst were measured by catalyzing the transamidation of carboxamideswith amines. We can come to a conclusion that the Fe₃O₄@DA-Pro nanocatalysts presented excellent catalytic activity for transamidation of carboxamideswith amines, and the catalysts can be used for at least 5 times. In the process of preparation of Fe₃O₄@DA-Pro nanoparticles, DA-Pro also played multiple roles: surfactant, linker and catalytic group. We come up with the theme of this dissertation: a green, simple and economical approach to prepare supported catalyst.Moreover, the nanocatalysts we prepared exhibited excellent catalytic activities for heterogeneous transamidation of carboxamideswith aminesunder neat condition. which has a certain value in lab research and industrial applications.