Miscibility of 1-alkyl-3-methylimidazolium bis(trifluoromethyl)sulfonyl imides with benzene and deuterated benzene

The liquid-liquid phase diagrams of 1-alkyl-3-methylimidazolium bis(trifluoromethyl)sulfonyl imides ([CnMIM][NTf2], n = 6,7,8) with C6H6 and C6D6 have been obtained. As the length of the alkyl chain decreases, the immiscible region is significantly enlarged and the phase diagram changes its shape from the most popular type that exhibits upper critical solution temperature to the “hourglass” type. The values of isotope effects on miscibility increase when the carbon chain length decreases and reach 4.4 K, 5.5 K, 7.1 K and even 50.1 K for n = 12,10,8,7, respectively.