Ionic liquids can be ecotoxic

Concerned about potential environmental risks as ionic liquids find wider use in industrial processes, researchers at AstraZeneca have studied the ecotoxicity of four classes of ionic liquids (Org. Process Res. Dev., published online June 28, dx.doi.org/10.1021/op060048i). These novel solvents impart interesting properties to many organic reactions and, because of their negligible vapor pressure, are often considered environmentally friendly replacements for volatile organic solvents. Andrew S. Wells and Vyvyan T. Coombe found that the toxicity of several regularly used ionic liquids to freshwater algae and invertebrates increased with the length of the ionic liquid's alkyl side chain. Those having the least acute toxicity were comparable with toluene and xylene, whereas the most toxic were orders of magnitude more harmful than methanol, acetonitrile, and dichloromethane. The results are consistent with other recent studies, researchers in the field say. Wells and Coombe suggest taking considerable care during process design in choosing which ionic liquid might be used and in avoiding the contamination of aqueous effluent streams.