New low-cost ionic liquids containing methyl-and ethyl-sulfate anions can be easily and efficiently prepared under ambient conditions by the reaction of 1-alkylimidazoles with dimethyl sulfate and diethyl sulfate. The preparation and characterization of a series of 1,3-dialkylimidazolium alkyl sulfate and 1,2,3-trialkylimidazolium alkyl sulfate salts are reported. 1,3-Dialkylimidazolium salts containing at least one non-methyl N-alkyl substituent are liquids at, or below room, temperature. Three salts were crystalline at room temperature, the single crystal X-ray structure of 1,3-dimethylimidazolium methyl sulfate was determined and shows the formation of discrete ribbons comprising of two anion-cation hydrogen-bonded chains linked via intra-chain hydrogen-bonding, but little, or no inter-ribbon hydrogen-bonding. The salts are stable, water soluble, inherently 'chloride-free', display an electrochemical window of greater than 4 V, and can be used as alternatives to the corresponding halide salts in metathesis reactions to prepare other ionic liquids including 1-butyl-3-methylimidazolium hexafluorophosphate.

No abstract

To enlarge the restricted knowledge about the hazard potentials of ionic liquids to men and the environment we have concentrated on systematically analysing the effects of 7 head groups, 10 side chains (mainly containing functional groups) and 4 anions on cytotoxicity. For our investigations, we used the promyelotic leukemia rat cell line IPC-81 as test system, with the reduction of the WST-1 dye as an indicator of cell viability. Our results show that most of the tested 100 ionic liquids generally exhibit a low cytotoxicity compared to previously investigated ionic liquids in consequence of their polar ether, hydroxyl and nitrile functional groups within the side chains. Those functional groups hamper cellular uptake by membrane diffusion and reduce lipophilicity based interactions with the cell membrane.In general, a low influence of the head group and a clear anion effect of the [(CF 3 SO 2 ) 2 N] 2 anion could be observed. Furthermore, we could confirm the general dependency between ionic liquid cation lipophilicity and cytotoxicity using a HPLC derived lipophilicity parameter. For one head group and for one side chain, deviations were obtained concerning this general dependency. This can be interpreted as a first hint for a more specific mode of action for these structural elements.

No abstract

The determination of chloride impurities in ionic liquids using ion chromatography is described. A wide range of cation-anion combinations may be analyzed using ion chromatography, including water-immiscible ionic liquids. For all ionic liquids studied, the limit of quantification for chloride was found to be below 8 ppm.