我們已合成出一系列在聯吡啶4,4′位置上有兩個氟化烷基側鏈的螯合劑 {4,4′-bis(RfCH2OCH2)- 2,2′-bipyridine , Rf=C8F17(1a), C9F19(1b), C10F21(1c)及C11F23 (1d) },使用4,4′-Bis(BrCH2)-2,2′-bipyridine與氟醇鈉進行親核反應而得並具有不錯的產率且其純化也簡易可行,合成產物可用GC-MASS、NMR、FT-IR來進行鑑定。其後1a-b與CuBr.Me2S反應形成特殊含氟長鏈銅催化劑(2a-d),此四種特殊的銅錯合物可應用於醇類的氧化反應,而又因為分配係數不同的關係可應用於兩種系統:1.氟/有機雙相系統2.溫控系統,由實驗可得知其催化活性可達八次以上且仍有很高的活性。 此特殊的催化劑在含氟長鏈螯合劑含氟量達62%以上時,可以被用在氟/有機雙相系統(有機相/氟相)如2c-d,因為對含氟溶劑相較於一般有機溶劑有較好的溶解度,並於低溫下對有機溶劑的溶解度很低甚至是沒有。氟/有機雙相反應於高溫時可互溶進行均相催化,並在反應後降溫分層,我們可利用異相分離在有機層收集產物而在氟相層回收催化劑,上述四種含氟長鏈螯合劑因具有含氟比重都達60%以上的特性故被應用於溫控系統(2a-d),反應物和金屬觸媒可以藉由溫度的控制來反應(高溫均相,低溫分層),藉由改變溫度而形成的反應系統,稱之溫控系統。利用離心的方式分離產物和金屬觸媒,觸媒的催化活性可達八次以上,經由這兩種系統可以有效率催化進行醇類的氧化反應並可經由溫度的控制輕易的回收催化劑。
We have synthesized a series of highly fluorinated bipyridine derivatives 4,4 '-bis(RfCH2OCH2)- 2,2'- bpy { Rf=C8F17(1a), C9F19(1b), C10F21(1c) and C11F23(1d)} by using (4,4′-bis(BrCH2)-2,2′-bpy) and fluorinated sodium alkoxide via the nucleophilic substitution reactions. The yield is very high and the product is easy to purify. These compounds can be analyzed by GC-MASS, NMR, FT-IR etc. The ligands 1a-d can then react with the CuBr.Me2S to form Cu complexes (2a-d), {Rf=C8F17(2a), C9F19(2b), C10F21(2c) and C11F23(2d)}. These four copper complexes 2a-d can then be applied for the aerobic alcohol oxidization. Since the distribution coefficients of ligands 1a-d are different, they can be used in two different systems: 1. fluorous biphasic system (FBS) 2. thermomorphic system (temperature-dependent): 1. FBS: when the fluorine content of ligands greater than 62%, e.g. ligands 1c-d, they showed higher affinity for the fluorous solvent than for common organic solvent, and they had little or no solubility for organic solvent at low temperature. Fluorous biphase system (FBS) becomes homogeneous at elevated temperature and showed two phases at low temperature. By using FBS we could get product from organic phase and recover catalyst from fluorous phase. 2. Thermomorphic system: which contains the soluble reactants and insoluble catalyst, becomes homogeneous during the reaction when being heated and then could be readily separated by cooling the reaction mixtures. After the reaction, the centrifugal method is then used to separate the products and metal catalyst. In particular, these catalysts can be easily recovered simply by cooling to room temp. Both systems are capable of efficiently catalyzing alcohol oxidation and the catalytic activities of the catalyst were excellent for eight times.
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