Synthesis, characterizationand toxicological studies of sustainable pyridinium based ionic liquids

Abstract

Ionic liquids (ILs) have attracted extensive research interest in recent years as environmentally benign solvents and it has also been considered as the “engineering solvents” having its tunable physical and chemical properties. ILs are typically consist of organic nitrogen-containing heterocyclic cations and inorganic or organic anions. The ILs designed and synthesized for carrying out specified task are referred as functionalized ILs, which show great application potential in various processes. The efforts to produce functionalized ILs, characterized them, and evaluate their properties and applications are presented in this thesis.

A series of twenty one achiral and chiral protic pyridinium based ILs were designed, synthesized and characterized. Out of these twenty one ILs, fifteen are achiral, three are chiral and rest are benzyl pyridinium cations based ILs. All pyridinium based ILs were characterized by a number of techniques including: FT-IR, UV-VIS, 1H-NMR, 13C-NMR spectroscopy.

Anti-microbial and toxicity studies were carried out using the well-diffusion technique with ILs solutions of two different concentrations. The six human pathogens were as follows: Bacillus cereus(+), Staphylococcus aureus(+), Sarcina lutea(+), Eschericia coli(-), Salmonella typhi(-), Pseudomonas aeruginosa(-).

Three protic pyridinium based ionic liquids were chosen to employ in Mannich reaction to synthesis of β-amino carbonyl compounds. The most attractive part of this work is that only small amount of protic ionic liquids (PILs) can catalyze this reaction in less time.

Keywords: Ionic liquids, Engineering solvent, Mannich reaction, β-amino carbonyl compound, Pyridinium cation.