| In this thesis, a new type of ether carbonyl rhodium functionalized ionic liquids,1-polyethylene glycol monomethyl ether-3-methyl imidazole carbonyl rhodium{[CH3O(CH2CH2O)nmim][Rhx(CO)y]}(n=8,16,22...), were successfully designed and synthesized. And their structure characterizations and catalytic performances were verified by us. By studing on the solubility in water and different organic solvents, a thermoregulated ionic liquid/organic biphasic catalysis system was developed. It provided a new way to achieve the " heterogenization and solution of problems for separation and recovery of noble metal catalysts in homogeneous reaction ".Firstly,m PEG tosylate intermediates were prepared by tosylation reaction of m PEG with p-toluene sulfonyl chloride. MPEG iodide was obtained by iodination of m PEG tosylate. Secondly, 1-polyethylene glycol monomethyl ether-3-methyl imidazole ionic liquids [CH3O(CH2CH2O)nmim]I ionic liquid precursor was obtained by quaternization reaction between the m PEG iodide and 1-methyl imidazole.Finally,[CH3O(CH2CH2O)nmim][Rhx(CO)y] was prepared by ion exchange reaction between [CH3O(CH2CH2O)nmim]I and K[Rhx(CO)y] which was obtained by reduction reaction of Rh Cl3·n H2 O with KOH/THF. In all infrared spectra,the characteristic carbonyl absorption bonds appeared near the 1955cm-1 and 1990cm-1,representing the presence of the [Rhx(CO)y]- anion, and the alternate ether linkages(-[C-O-C]n-) absorption bonds appeared near 1100cm-1. These represented the formation of polyether structure. Appearance of the carbonyl splitting bands near2015 cm-1 indicated the most distorted anion out of the ionic liquid due to the close proximity of the anion/cation pairs. Additionally, the characterization of NMR not only proved the existence of the ethoxy groups and rhodium carbonyl anion, but also showed purity of the ionic liquid catalyst. According to TGA analysis spectrum the ionic liquid, which has excellent heat-stability, can be applied to most of thecarbonylation reactions. Determination of the melting point(~50℃)also provided strong evidence for the attribution of the prepared substances, which was an ionic liquid.The solubility of the ionic liquids was determined qualitatively in water and different organic solvents. They were all well dissolved in intensive polar organic solvents, while insoluble in some weak polar solvents.The solubility would rise with the increasing the polymerization degree in some solvents. The carbonyl rhodium ionic liquid synthesized could be formed in a perfect solution system with water. This characteristic property of the ionic liquids will prove useful in their application in convenient and environmentally friendly catalytic system using water as green solvent.Furthermore, in some organic solvent, the miscibility was not found even if the temperature rose to certain value through the experiment. However, the ionic liquid and PEG400/1,4-dioxane/n-heptane could build "homogeneous in high temperature,two phase in low temperature" thermoregulated phase separation biphasic catalytic system.The thermoregulated system was applied to hydroformylation of styrene.Under the temperature 120℃, syngas(VCO/H2=1) pressure 4.0 MPa, triphenylphosphine as ligand, reaction time 6 h, conversion of styrene was 98.6%, Selectivity of α-aryl propionate was 72.3%. After the reaction, by simple decantation, the bottomed ionic liquid PEG phase can be recycled and used for the next reaction. A possible reaction mechanism had also been proposed in this paper. |
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