Ionic Liquids Lab Report

1. INTRODUCTION TO IONIC LIQUIDS 1.1 Introduction

Ionic liquids have been generating increasing interest over the last decade. It is a testament to the speed with which ionic liquids have caught the popular chemical imagination that in 1999 a monograph titled “Modern Solvents in Organic Synthesis”, could be published in which ionic liquids received no mention at all; a situation that would be unimaginable now. Much of this interest is centred on their possible use as “greener” alternatives to volatile organic solvents (see below). There is, however, also a more fundamental interest in how the unusual solvent environment that they provide for solute species might affect reactions conducted in them. There have been a number of excellent

non-polar), highly viscous and frequently exhibit low vapor pressure. Their other properties are diverse: many have low combustibility, excellent thermal stability, wide liquid regions, and favorable solvating properties for a range of polar and non-polar compounds. Many classes of chemical reactions, such as Diels-Alder reactions and Friedel-Crafts reactions, can be performed using ionic liquids as solvents. Recent work has shown that ionic liquids can serve as solvents for bio catalysis. The miscibility of ionic liquids with water or organic solvents varies with side chain lengths on the cation and with choice of anion. They can be functionalized to act as acids, bases or ligands, and have been used as precursor salts in the preparation of stable carbenes. Because of their distinctive properties, ionic liquids are attracting increasing attention in many fields, including organic chemistry, electrochemistry, catalysis, physical chemistry, and engineering; see for instance magnetic ionic

“Ionic Liquids” was the title of Chapter 6 of the textbook Modern Electrochemistry by Bockris and Reddy, published in 1970: it discussed liquids ranging from alkali silicates and halides to tetraalkylammonium salts. The modern era of ionic liquids stems from the work on alkylpyridinium and dialkylimidazolium salts in Colorado in the late 1970s. The term ionic liquids was introduced to cover systems below 100°C, one reason being to avoid the words “molten salts” in phrases such as “ambient temperature molten salts,” another to create an impression of freshness and a third, perhaps, for patent purposes. The first “Conference on Ionic Liquids” took place in Salzburg in 2005, Molten Salts in Toulouse in 2005 had one of ten sessions devoted to Ionic Liquids; but the International Symposia on Molten Salts of ECS from 1976 to the present have not shown discrimination on the basis of temperature, beyond One property that we emphasized recently is the molarity of the liquid (a straightforward quantity except for mixed systems such as a basic chloroaluminate containing both Cl- and AlCl4- in significant