Toxicological study of some ionic liquids

The increasing interest in the development of new environment-friendly solvents has led to the synthesis of new materials that minimize the impact of solvents on the environment. However, most of the published studies on green solvents focus primarily on their physicochemical properties, with limited emphasis on their toxicological risk in the environment. In this study, the acute toxicities of five ionic liquids, 1-propylpyridinium tetrafluoroborate, 1-butylpyridinium tetrafluoroborate, 1-butyl-2-methylpyridinium tetrafluoroborate, 1-butyl-3-methylpyridinium tetrafluoroborate and 1-butyl-4-methylpyridinium tetrafluoroborate, on Vibrio fischeri and Daphnia magna are evaluated. In the latter bioassay, the presence and position of a methyl group on the pyridinium ring or the length of the chain attached to the nitrogen atom seem to be the key factors for toxicity. In the Vibrio fischeri study, the alkyl chain attached to the nitrogen atom has a considerable influence on EC50 values. Moreover, quantitative structure activity relationship studies are performed to relate their physicochemical properties with their acute toxicity.