Handling3




In most of the applications, the stability of ionic liquids, at least at a certain extent, is crucial for optimum process performance.
It is widely claimed that many of the new ionic liquids are both air and moisture stable; some are even hydrophobic. While it is true to say that the new liquids are free from many of the hydrolysis problems that make the halogenoaluminates(III) so difficult to handle, most ammonium and imidazolium salts are hygroscopic and if used in open vessels, hydration will almost certainly occur.
For example, despite their widespread use, IL featuring PF6- and BF4- have been reported to sometimes decompose when heated in the presence of water, giving off HF.

The degree to which this is a problem will depend on the use to which the ionic liquid is being put and what solutes are being used. For instance, the small amounts of highly reactive species that are used as catalysts can be deactivated by even the smallest amounts of water. It would be recommended handling under an inert atmosphere if the ionic liquids are to be used for air- or moisture-sensitive solutes.

Nonetheless, these new ionic liquids are much easier to handle than the halogenoaluminate(III) systems and are opening up new avenues for research, particularly in homogeneous catalysis. Furthermore, previous studies have indicated that, although not 100% inert, certain ionic liquids incorporating 1,3-dialkyl imidazolium cations are generally more resistant than traditional solvents under certain harsh process conditions, such as those occurring in oxidation, photolysis and radiation processes.

Among the room-temperature ionic liquids that have received attention are [EtNH3][NO3], [emim][NO3], and [emim][ClO4]. Organic nitrates and perchlorates are potentially explosive, especially when rigorously dried. Although no problems have been reported, care should be used at all times when handling them.

Nowadays the most widely used ionic liquids are probably N,N-dialkylimidazolium salts.

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