Study On The Unit Reactions Of Organic Synthesis In Ionic Liquid Biphasic Systems

Recently, ionic liquids research has become a new field of green chemistry. Due to their favorable properties such as non-inflammability, negligible vapour pressure, reusability and high thermal stability, ionic liquid technology has been successfully applied to many areas of chemistry including organic and inorgnic synthesis, biphasic catalysis, separation proeesses, electrochemistry etc. Separation and recovery of catalyst with high efficiency plays an important role in green chemistry. Ionic liquids of catalytic system possess the thermoregulated biphasic behavior of "mono-phase under high temperature, bi-phase under room temperature" and phase transfter catalysis have been attracted much attention due to their advantages of both homogeneous and heterogeneous eatalysis with high product yield and the easy separation of product from catalytic system.The main objective of this dissertation is to perform the chloromethylation of aromatic hydrocarbons, animation of organic halides, hydrolysis of organic halides、epoxides and esters, C-O coupling of organic halides, oxidation of organic halides, and the reductive homocoupling of benzyl and aryl halides in ionic liquids with a view to develop new environment-friendly methods, and the specific research contents include the following aspects.Two temperature-dependent biphasic systems, PEG1000-DAIL/methylcyclohexane and PEG1000-DIL/methylcyclohexane, were used as isolated catalyst in the chloromethylation of aromatic hydrocarbons, and the effect of reaction conditions on the catalytic reaction was investigated. It was found that a new chloromethylation reaction system using PEG1000-DIL in combination with methylcyclohexane has been developed, which is capable of converting aromatic hydrocarbons into the corresponding mono-chloromethyl-substituted aromatic compounds in good to excellent isolated yield. And the new dichloromethylation reaction system using PEG1000-DA.IL in combination with methylcyclohexane has also been developed, which is capable of converting some aromatic compounds (e.g. biphenyl,p-xylene, m-xylene, o-xylene,1,2,3,4-tetrahydro-naphthalene) into the corresponding dichloromethyl-substituted aromatic compounds in good to excellent isolated yield. Mild reaction conditions, ease of workup, high yields, stability, easy isolation of the compounds, good thermoregulated biphasic behavior of IL, and excellent recyclability of the catalyst are the attractive features of this methodology, which is a good example of green chloromethylation method.A simple, efficient, and environmentally friendly procedure for the amination of organic halides catalyzed by CuSO4·5H2O in PEG1000-DIL/methylcyclohexane temperature-dependent biphasic system has been developed. A wide range of aryl, benzylic, allylic, and aliphatic halides were found to be applicable to the catalytic system. This procedure include many advantages such as mild reaction conditions, simplicity of operation, high yields, easy isolation of products by a simple decantation, good thermoregulated biphasic behavior of the IL, and excellent recyclability of the catalytic system.Three kinds of new PEGiooo-based dicationic acidic ionic liquids (PEG1000-DAIL[BF4], PEG1000-DAIL[PF6] and PEGiooo-DAIL[OTf]) have been synthesized from the ionic liquid PEGiooo-DAIL, and found that these ionic liquids can also exhibite good temperature-dependent phase behavior with toluene, and their applications in hydrolysis of organic halides, epoxides, and esters have been extensively studied. The results showed that Fe2(SO4)3was found to be the most effective cocatalyst in terms of yield and reaction rate in PEG1000-DAIL[BF4]/toluene temperature-dependen biphasic system. And the PEG1000-DAIL[BF4]/Fe2(SO4)3catalytic system was found to be more effective in hydrolysis of organic halides than that of both epoxides and esters. After the completion of the reaction, the phase-separation appeared along with cooling, and a complete oil-water biphasic system was formed again after being cooled to room temperature. The product can be easily isolated by a simple decantation, and the catalytic system can be recycled and reused without loss of catalytic activity.Nine kinds of new PEG1000-based dicationic ionic liquids based on transition metals (PEG1000-DAIL[CdCl3], PEG,ooo-DAIL[FeCl3], PEG1000-DAIL[FeCl4], PEG1000-DAIL[CuCl2], PEG1000-DAIL[CuCl3], PEG1000-DAIL[ZnCl3], PEG1000-DAIL[PdCl3], PEG1000-DAIL[MnCl3] and PEG1000-DAIL[AlCl4) have been synthesized from the ionic liquid PEG1000-DAIL, and found that these ionic liquids can also exhibite good temperature-dependent phase behavior with toluene, and their applications in C-O coupling of organic halides with phenols and alcohols have been extensively studied. The results showed that PEG1000-DAIL[CdCl3] demonstrated the best performance, and an experimentally simple and efficient protocol for the C-O coupling of organic halides with phenols and alcohols in PEG1000-DAIL[CdCl3]/toluene temperature-dependent biphasic system has been developed.A series of ionic liquids of transition metals based on1-alkyl-3-methylimidazolium cation [Cnmim]+) as phase transfer catalysts were synthesized, and their applications in the selective oxidation of organic halides to aldehydes and ketones and reductive homocoupling of benzyl and aryl halides have been extensively studied. A simple, mild, and efficient procedure for the oxidation of organic halides to aldehydes and ketones with H5IO6in ionic liquid [C12mim][FeCl4] has been developed. The oxidation reactions afford the target products in good to high yields and no overoxidation was observed. The products can be separated by a simple extraction with organic solvent, and the catalytic system can be recycled and reused without loss of catalytic activity. A facile and efficient synthesis of bibenzyl and biaryl derivatives by reductive C-C homocoupling reaction has been described. Treatment of benzyl and aryl halides with metallic zinc and copper powder in the presence of a catalytic amount of [C12mim][CuCl2] under ligand-and base-free conditions gives the corresponding bibenzyls and biaryls in good to high yields. The product can be isolated by a simple extraction with organic solvent, and the advantages of our procedure include simplicity of operation, low cost, high yields, and excellent recyclability of the catalyst.