Study On Aromatic Nucleophilic Substitution And 1,3-Dipolar Cycloaddition In Imidazolium Ionic Liquids And Their Solvent Effects

This dissertation focuses on developing the use of imidazolium-based ionic liquids in place of organic solvent as the reaction medium to carry on the organic reaction.and establishing and verifying the solvent effects of imidazolium-based ionic liquids for promoting mechanism of certain organic reactions.The research mainly concentrates on the aromatic nucleophilic substitution reaction and 1.3-dipolar cycloaddition reaction in imidazolium-based ionic liquids and the study of the solvent effects.First,the aromatic nucleophilic substitution reaction in imdazolium-based ionic liquids was studied.The reaction yield can be improved by adding inorganic base in imdazolium-based ionic liquids,which replaces traditional organic solvent as the reaction medium.In addition,this paper proves that the hydrogen bondings between ionic liquid and the reactants is formed through the controlling experiment and the nuclear magnetic tracking experiment,and the reaction is promoted through the electrophile-nucleophile dual activation mechanism.The optimum reaction conditions are as follows:using 1.1 eq of K3PO4 in[Omim]Br at 80 ? for 12 h,giving the product up in good yields(up to 99%).Compared with the traditional method,this method has some advantages including high reaction yield,recycled solvent,avoiding the use of toxic,volatile organic solvents and simple post-processing.Then,the 1,3-dipolar cycloaddition reaction in imdazolium-based ionic liquids was investigated.Adding oxidant TBHP and inorganic base can effectively improve the conversion rate of reaction.Similarly,through the controlling experiment and nuclear magnetic tracking experiment,it is shown that there are many non-covalent bonding effects between ionic liquids and reactants,which can effectively promote the reaction.The optimum reaction conditions for alkene as the reactant are as follows:using 3.0 eq of Na2CO3 and 2.0 eq of TBHP in[Omim]Br at 110 ? for 22 h,giving the product up in good yields(up to 90%),and the optimum reaction conditions for alkyne as the reactant are as follows:using 1.2 eq of CS2CO3 in[Omim]Br at 50 ?for 6 h,giving the product up in good yields(up to 97%).The protocol provides some merits like mild reaction condition,high yield and easy of the product isolation,and reaction medium can be recycled through simple extraction,so it is more suitable for large-scale operations.