Phosphonium ionic liquids

This work was financially supported by Cytec Industries, Canada, providing a primary focus on phosphonium ionic liquids, their synthesis and characterisation. Four different series of tetraalkylphosphonium ionic liquids were studied, alkyltrioctyl-, alkyltrihexyl-, alkyltributyl-phosphonium chlorides and alkyltrihexylphosphonium bistriflamides, with variation of the alkyl chain from methyl to tetradecyl. This thesis describes their synthesis, their detailed characterisation (including spectroscopic, analytical and structural methods), and analysis of the relationship between their structure and their physical properties, and comparison with their ammonium analogues. Most of the salts prepared were new, and this is the first systematic study of coherent series of phosphonium ionic liquids. One of the series ([P8 8 8 n ]CI) exhibited an alternation effect in both, density and viscosity trends, which is the first evidence of such behaviour for any class of ionic liquids. This effect is attributed to the even and odd alkyl chain change in the cation, which has been previously observed in other classes of molecular organic compounds. Although the alternation effect was not witnessed in any other series of phosphonium ionic liquids (for the other chloride series, the number of salts liquid at room temperature was a restriction, while lack of zig-zag trend in the bistriflamide series might be pointing to the influence of anion on such behaviour), this finding (in combination with literature data and crystal structure presented for [P4 4 43]Cl) is pointing to possible interesting solid/glass-liquid rearrangements. The tetraalkylphosphonium ionic liquids were found to have superior thermal stability and viscosity to their tetraalkylammonium analogues. A part of this work was performed in cooperation with the research group of Dr. Cristina S. Pereira in Portugal: this focussed on ecotoxicity studies of [P4 4 4 n]Cl. These studies revealed that toxicity dramatically changes with changing alkyl substituent, but also suggested the nature of the mechanism of toxicity. This is the first study where the interaction of ionic liquids with cellular boundaries has been examined with fluorescence microscopy.EThOS - Electronic Theses Online ServiceGBUnited Kingdo