110th Anniversary: Properties ofImidazolium-Based Ionic Liquids Bearing Both Benzylic and n ‑Alkyl Substituents

Reports of imidazoliumionic liquids (ILs) with at least one benzylic substituent bound to the imidazolium cation are far less common than the ubiquitous 1-alkyl-3-methylimidazolium ILs ([C(n)mim][X]). Yet, there is significant motivation to determine structure-property relationships for imidazolium-based ILs with at least one benzylic substituent. Not only are these ILs just as straightforward to synthesize as [C(n)mim] [X] ILs, but ILs with benzylic substituents are also representative segments of poly(ILs) and ionenes where imidazolium cations with benzylic groups are commonly found. This report focuses on the effects of benzyl and methylbenzyl substituents on the density and viscosity of a series of imidazolium cations paired with bis[(trifluoromethyl)sulfonyl]imide (more commonly known as bistriflimide) ([Tf2N] ) anions. Furthermore, the solubility of CO2 in 1-benzyl-3-methylimidazolium bistriflimide [Bnmim][Tf2N] (CAS: 433337-24-7) was measured at 303.15, 318.15, 333.15, and 348.15 K at pressures in the range of 1-9 bar.