Synthesis and Structural Characterization of Nickel(II) Complexs Supported by Aminodipyridylphosphine Oxide Ligand.The Catalytic Application to Thioacetalization of Aldehyde
| Autor: | Bo-yi Jiang, 江柏誼 |
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| Rok vydání: | 2008 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 96 We have successfully synthesized the organonickel Lewis acid complex, [HO(CH2)11N(H)P(O)(2-py)2]NiBr2 (3) in quantitative yield. A mixture of (DME)NiBr2 and HO(CH2)11N(H)P(O)(2-py)2¬ in CH3CN was allowed to stir at 25 oC for 12 hours. The resulting solution was concentrated and a small portion of hexane acting as diffusion solvent was added at 0 oC to give [HO(CH2)11N(H)P(O)(2-py)2]NiBr2 as green precipitates. The green powdered products were obtained by decanting off the supernatant followed by drying under vacuum. The complex 3 was very stable against moisture and air. Its solid form can be stored in air for months and when dissolving in solution it can also stay unchanged for at least 48 hours without any decomposition. The NMR analysis of complex 3 showed the occurrence of obvious contact shift and broadening of all proton signals. The EPR spectral analysis and SQUID dada also indicated a paramagnetism of a triplet spin state associated with a tetrahedral Ni (II) center for complex 3. We have also used FT-IR and FAB-MS spectrometry to further verify the composition and the coordination linkage of nickel with pyridyl nitrogen atoms. In the second part of this thesis, an emphasis was made on the application of this organonickel Lewis acid as catalyst for a series of thioacetalization condensation reactions. The thioacetalization condensation reactions of various aldehydes and dithiols (1,2-ethanedithiol and 1,3-propanedithiol) in a mixed solvent system of CH2Cl2 and MeOH in a volume ratio of 5:1 were catalyzed by 10 mol% of complex catalysts 3 at ambient temperature and at reflux. The catalytic systems were found very efficient to give excellent yields in minutes. In addition, when the 脉–carbon next to aldehyde baring an electron-withdrawing substituent would provide better reactivity in the following order: para-hydroxybenzaldehyde > benzaldehyde > para-nitrobenzaldehyde. In addition, the increase of steric hindrance around aldehydic carbonyl would certainly decrease the reactivity as expected. Moreover, our target organonickel catalyst [HO(CH2)11N(H)P(O)(2-py)2]NiBr2 (3) can be reused many times in thioacetalization condensation reactions. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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