Studies of Latent Acidity and Neutral Buffered Chloroaluminate Ionic Liquids

摘要

Studies on ionic liquids composed of aluminum chloride and 1-ethyl-3- methylimidazolium chloride were carried out, with emphasis on understanding and explaining acidity and latent acidity in 'neutral buffered' melts. It was found that alkaline earth, as well as alkali metal salts, function as buffering agents, with both showing the 'latent acidity' effect. Both Bronsted and Lewis acidities were investigated in an effort to understand the role of the type and concentration of the 'buffering' alkali or alkaline earth salt. A silver/silver chloride/chloride ion electrode was found to function as a reversible chloride ion indicator over a very narrow range of melt acidity about the neutral point. This electrode, and relative solubility product measurements, were employed in these studies. It was found that the latent acidity could be explained in terms of the solubility product relationship of the buffering salt, with the salt having the smallest solubility product creating the most acidic melt. Some work was also carried out on non-haloaluminate melts.