How Toxic Are Ionic Liquid/Acetonitrile Mixtures?

Acetonitrile (ACN) is suggested to be a cosolvent of room-temperature ionic liquids (RTILs) in order to decrease their unprecendented viscosity and increase ionic transport. Nevertheless, apart from its doubtless virtues, ACN possesses moderate toxicity to animals due to its high volatility at medium temperatures and subsequent ability to form highly toxic compounds, including cyanogen. Because of these considerations, ACN has been recently banned in a series of commercial applications. In turn, RTILs are usually positioned as nontoxic, green solvents, mainly due to their negligible volatility. This Letter investigates the volatility of the imidazolium-based RTILs/ACN mixtures, where RTILs are represented by 1-ethyl-3-methylimidazolium tetrafluoroborate and 1-butyl-3-methylimidazolium tetrafluoroborate. On the basis of the atomistic precision simulations of liquid/vapor interfaces over a wide composition range, we evidence that RTILs are able to noticeably decrease the volatility of ACN, and hence, reduce a hazard. The reported data favor wide technological applications of RTILs/ACN mixtures.