Vaporisation of an ionic liquid near room temperature

Abstract

The temperature at which the vapour phase of the ionic liquids (ILs) 1-ethyl-3-methylimidazolium bis[(trifluoromethane)sulfonyl]imide, [C(2)C(1)Im][Tf(2)N], and 1-ethyl-3-methylimidazolium ethylsulfate, [C(2)C(1)Im][EtOSO(3)], can be detected was investigated using line-of-sight mass spectrometry (LOSMS). By optimising the detection system used in previous experiments, the lowest temperature for which vapour was detected for [C(2)C(1)Im][Tf(2)N] was approximately 340 K, whereas for [C(2)C(1)Im][EtOSO(3)] it was approximately 390 K. Initial investigations also show that the temperature at which measurements are made affects the enthalpy of vaporisation at 298 K, Delta(vap)H(298). The reasons for these differences in Delta(vap)H(298) with respect to temperature are discussed. The vapour pressure of both ILs is estimated at far lower temperatures than previously achieved and extrapolations to room temperature are given.