Studies On Syntheses, Properties And Applications Of Br(?)nsted Acidic Ionic Liquids

Ionic liquids (ILs) that are composed entirely of ions and are liquids at ambient or far below ambient temperature, have been extensively used as a potential alternative to toxic, hazardous, flammable and highly volatile organic solvents. Indeed, their many unique and attractive physicochemical properties, including negligible vapor pressure, multiple solvation interactions with organic and inorganic compounds, excellent chemical and thermal stability, high ionic conductivity and large electrochemical window make ILs great candidates for volatile organic compoundsreplacements. In addition, the physicochemical properties such as the viscosity, hydrophobicity, density, and solubility of ILs can be tuned by simply selecting different combinations of cations and anions as well as attached substituents to customize ILs for many specific demands. This is why ILs have been recognized as"designer solvents."All these interesting combination of properties opens the road to a wide range of applications, including extraction, organic synthesis and catalysis, inorganic synthesis, separation, nanomaterial synthesis and enzymatic reactions。Recently, Br?nsted acidic ionic liquids, which combine both advantages of solid acids (e.g. nonvolatility and easy recycle) and that of liquid acids (e.g. greater effective surface area and potential activity of liquid phase), have been designed and used as dual solvent-catalysts for Fisher esterification, alcohol dehydrodimerization pinacol/benzopinacol rearrangements, and the electrophilic substitution of indoles with aldehydes. this implementation of task specific ionic liquids (TSILs) further enhances the versatility of classical ionic liquids where both reagent and medium are coupled . The union of reagent with medium has been found to be a viable alternative approach toward modern synthetic chemistry especially when considering the growing environmental demands being placed on chemical processes.Developments of new basic reactions and new synthetic methods are the basis for the innovation and advance of organic chemistry .Based on the research achievement of our group in room temperature ionic liquids, my thesis starts from the design and synthesis of room temperature ionic liquids, aming to develop a new synthetic strategy to provide a general and simple route to the Ritter reaction of tertiary alcohols with nitriles , investigations were also carried out on the synthetic methodology for Application of the tert-amino effect"for preparation of potentially useful aminals compounds under ionic liquid. The main content of this paper is outlined as following:The Ritter reaction is one of the most important carbon-nitrogen bond forming reactions and is widely used to synthesize amide compounds, which are important synthetic intermediates for various pharmaceuticals and natural products. The classical Ritter reaction of tertiary and secondary alcohols with nitriles was catalyzed by strong protic acids such as concentrated sulfuric acid and some alternative acids .These procedures have advantages such as cleaner reactions, easier workup, and easier recovery and reuse of catalysts. In spite of that, it is still full of challenge to explore high catalytic activity and reusable catalysts for Ritter reaction.In this paper, we speculate that Br?nsted acidic ionic liquids, due to their strong acidity and high polarity, maybe not only favor acid catalysis, but also favor stability of the carbocation intermediates in Ritter reaction. With the aim of finding efficient, cost-effective and reusable catalysts, we investigated the Ritter reaction of nitriles with tertiary alcohols as well as secondary alcohols in presence of Br?nsted acidic ionic liquids. To the best of our knowledge, this is the first report on the application of Br?nsted acidic ionic liquids as dual solvent-catalysts for Ritter reactionThree classes twenty-nine kinds Br?nsted acidic ionic liquids (ILs) were synthesized and used as dual solvent-catalysts for the Ritter reaction of benzonitrile with tert-butanol. In particular, IL ([NSPTEA][OTF] )( N-(4-sulfonic acid) propyl triethylammonium trifluoromethanesulfonate) showed excellent catalytic activity for the Ritter reaction. In the presence of IL, various nitriles and tertiary alcohols as well as secondary alcohols were converted smoothly to the corresponding amides in good to excellent yields. In addition, this cost-effective ionic liquid [NSPTEA][OTF] was easily separated from the reaction mixtures by extraction with a small amount of water, and recycled five times without any significant loss in activity.The term"tert-amino effect"has been used to describe a diverse number of reactions that proceed via intramolecular, C-C, or C-X bond-forming redox processes within conjugated systems.1 These reactions involve the functionalization of a C-H bondαto a tertiary amine nitrogen and have also been referred to as"α-cyclization of tertiary amines". In the vast majority of cases, these reactions are promoted thermally and relatively little effort has been devoted to developing reaction approaches. To ultimately expand the scope and applicability of these intriguing transformations, it is desirable to identify new synthetic methods that would allow for milder reaction conditions as well as shorter reaction times.In this paper, four kinds Br?nsted acidic ionic liquids (ILs) ([HMIM][OTF], [NSPTEA][OTF], [MPSIM][OTF], [HHDMG][OTF]) were synthesized and used as dual solvent-catalysts for the"tert-amino effect"ring-closure reaction of 2-(pyrrolidin-1-yl)benzaldehyde with aniline.Unluckily,none but [MPSIM][OTF], [HHDMG][OTF]) given the product of the ring-closure reaction, but the yield were not absorbing. At last we attempt Br?nsted acid-promoted syntheses of aminals from o-aminobenzaldehydes and aromatic amines that proceed in water-solubility IL[BMIM][BF4] a simple single-flask procedure.This is the first work for"tert-amino effect"ring-closure reaction in ionic liquids.