Design, Synthesis, Characterization Of Iron Complexes And Their Catalysis On The Preparation Of Cyclic Carbonate From The Coupling Between Carbon Dioxide And Epoxides

In this dissertation, we report the synthesis and characterization of N-containing organic ligands and their coordination to Fe(Ⅲ) and/or Fe(Ⅱ), and synthesis of cyclic carbonate from coupling reaction of carbon dioxide with epoxides catalyzed by the iron complexes. It consists of following two major sections:1. Four multidentate ligands containing N, O ligating atoms, ethyl6-(bis(pyridin-2-ylmethyl)amino)hexanoate (L1),6-(bis(pyridin-2-ylmethyl)amino) hexanoic acid (L1), ethyl6-((2-hydroxybenzyl)(pyridin-2-ylmethyl)amino)hexanoate (L2) and6-((2-hydroxybenzyl)amino)hexanoic acid (L2’), were designed and synthesised. The coordination chemistry of the ligands with Fe(Ⅲ) was carried out. All of the ligands and complexes were fully characterized. And the crystal structure of [FeCl3L1] and [FeCl3L1"] were determined using X-ray single crystal diffraction analysis. The catalysis of the two Fe (Ⅲ) complexes on the formation of cyclic carbonate from the coupling of CO2to epoxid es were studied. Further research on catalytic activity of these two complexes for the generation of cyclic carbonate from epoxides and CO2were carried out. The catalytic activities of these two complexes were investigated at100℃under normal pressure and high pressure (1MPa), respectively, by using epoxy chloropropane as substrate to prepare cyclic carbonate. The result showed that the conversion rate of the substrate were over90%under high pressure after4h’s reaction and>95%under atmosphere pressure after72h’s reaction without the presence of any co-catalyst. In addition, catalytic activities of these two catalysts were assessed under atmosphere pressure after72h’s reaction and the result showed that both the activities of the catalysts were high, and [FeCl3L1"] showed better performance than [FeCl3L1], whose best conversion rate was above98%.2. We designed and synthesized two N-Heterocyclic Carbenes (NHC) bromides, BrCH3lmCH2PyImCH2CH3Br (2,6-bis[(1-methylimidazolium)methyl]pyridine dibromide) and BrMesitylImCH2PyCH2IImMesitylBr (2,6-bis[1-(3,5-dimethylbenzyl) imidazolium]pyridine dibromide). And their coordination reaction with Fe(Ⅱ) was studied. We attempted to explore the catalytic activity of the Fe(Ⅱ) complex,[FeClxCH3ImCH2PyCH2ImCH3] on the synthesis of cyclic carbonate from the coupling of CO2with epoxy chloropropane under high pressure(1MPa) and atmosphere pressure.