1-Alkyl-3-methylimidazolium iodides substituted with
a
(Fraunhofer Institute of Applied Polymer Research) for
support during viscosity measurements. Furthermore, V.S.
and H.R. gratefully acknowledge the DFG for financial
support within the priority program SPP 1191.
methyl or ethyl group are synthesized from 1-methylimidazole
and the corresponding alkyl iodide using a 25 wt% excess on
the alkyl halogenide at room temperature. tert-Butyl methyl
ether is used as solvent in the case of methyl iodide and ethyl
iodide because of the high exothermic reaction in these
examples. The volume ratio of the solvent to the alkyl iodide
is 1 : 1. The 1-propyl-3-methylimidazolium iodide is synthesized
using a 5 wt% excess of the propyl iodide in bulk. 1-alkyl-3-
methylimidazolium chlorides substituted with a butyl, hexyl,
octyl or decyl chain are synthesized from 1-methylimidazole
and the corresponding alkyl chloride in bulk at 65 1C in the
case of butyl chloride and hexyl chloride and at 70 1C in the
case of octyl chloride and decyl chloride using 5 wt% excess on
the alkyl chloride. 1-Alkyl-3-methylimidazolium halogenide
obtained and lithium bis(tifluoromethylsulfonylimide) from
Iolitec are separately dissolved in water. The amount of each
starting material is 1 g per 1 ml water. A 5 wt% excess of the
lithium bis(trifluoromethylsulfonylimide) relative to the
necessary stoichiometric amount is used for anion metathesis.
The water solutions are unified under stirring and kept further
stirring for 18 h. After stirring, ethyl acetate or methylene
chloride (500 ml solvent relative to 70 g of the imidazolium
iodide) is added to the water solution. Both solvents result in
similar products. Methylene chloride is preferred because of
phase inversion in the case of ethyl acetate. The organic phase
is separated, washed 8 times with 300 ml water each, and
filtered over sodium sulfate. The solvent is evaporated from
the organic solution in vacuo. The remaining ionic liquid is
dried in vacuo (1–4 mbar) at a temperature between 70 and
90 1C for 3 days. No remaining halide was detected after
addition of a solution of AgNO3 dissolved in a water–acetone
mixture. The water content of these ionic liquids is lower than
1000 ppm.
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Acknowledgements
We gratefully acknowledge A. Laschewsky for the use of
laboratory equipment, H. Wetzel (Fraunhofer Institute of
Applied Polymer Research) for water analysis using the
Karl Fischer Method, and E. Gornitz and K. Blumel
¨
¨
ꢀc
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Strehmel, Veronika
