Ionic liquids (ILs) are known to be extremely hygroscopic; if left in ambient laboratory conditions, they rapidly absorb atmospheric water.  This has a non-negligible impact on their properties, influencing their viscosity, conductivity, density, and surface tension.  Therefore, it is important for scientists working with and characterizing ionic liquids to know precisely the water content of their samples when they are performing their experiments (such as measurements of conductivity or viscosity) to avoid confusion and irreproducibility.  At present, the prevailing method used for this measurement is Karl Fischer Coulometric titration.  This method employs irreversible electrochemical reactions and is thus a destructive technique.  Because the Coulometric titration requires additional sample to be expended for increasingly dry IL sample conditions, it is urgent to establish alternative non-destructive methods to analyze the water content during synthesis of novel ionic liquids.  We describe how standard infrared spectroscopy and NMR methods can be used to monitor the the spectra of water dissolved in trace quantities in ILs as a function of both concentration and temperature.

Non-destructive determination of the water content in room-temperature ionic liquids

244th National Meeting (2012)

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