Synthesis of ionic liquids: application to wittig, reduction and aromatic nucleophilic substitution reactions

Abstract

As part of an ongoing program in the area of green chemistry, we have considered the synthesis of room temperature ionic liquids and their application as reaction medium in organic transformations. The efforts and contribution towards the preparation and application of ionic liquids have been summarized in the form of this thesis. The thesis entitled ?Synthesis of ionic liquids: Application to Wittig, reduction and aromatic nucleophilic substitution reactions? is divided into five chapters. CHAPTER-I: Introduction to ionic liquids This chapter deals with the 12 principles of green chemistry, ?E? factor, atom efficiency, possible alternative solvents and their applications, ionic liquids, and a few examples on the application of RTILs in organic synthesis. CHAPTER-II: Synthesis and characterization of citronellal based chiral ionic liquids Chapter 2 deals with the preparation and characterization of a series of chiral ionic liquids starting from the chiral pool citronellal. Several new chiral ionic liquids were prepared starting from both the isomers of citronellal with dialkyl amine as the amine source. The Schiff base, thus obtained, was reduced and further reacted with alkyl halides to give ionic liquids. The strategy could begeneralized with several dialkyl amines to design chiral ionic liquids. CHOHCHOHa. X = I, R = Meb. X = I, R = Etc. X = Br, R = n-Prd. X = Br, R = i-Pre. X = Br, R = n-Bu(S)-18(S)-20a-e(R)-18(R)-20a-eHNRHNR(S)-19a-e(R)-19a-eHNRHNRXXXX Figure: 2.1 Retrosynthesis of Citronellal-based chiral ionic liquids. Most of the ionic liquids prepared in this series were found to be liquids at room temperature. CHAPTER-III: Application of ionic liquids in the Wittig reaction and synthesis of lacidipine using ionic liquids Chapter 3 deals with the application of ionic liquids in the Wittig reaction. The generality of the methodology has been demonstrated with various substituted benzaldehydes and ylides.