A Highly Conductive RTMS; Alkylimidazolium Fluorohydrogenates

摘要

Reaction of some N-alkylimidazolium chloride or N-alkylimidazole with anhydrous hydrogen fluoride (HF) gives involatile room temperature molten salt, XF·2.3HF where X -1-ethyl-3-methylimidazolium (EMI), 1-methylimidazolium (MeIm), 1-butyl-3-methyl-imidazolium (BMI), 1-hexyl-3-methylimidazolium (HMI). The highest specific conductivity at 298 K, 10~2 mScm~(-1), is observed for EMIF·2.3 HF. Substitution of the proton or the longer alkyl groups for the ethyl group of the cation decreases the conductivity. These salts are stable in air and do not etch a Pyrex glass container at ambient conditions, EMIF·2.3HF does not freeze above -90℃ or lose HF below 100℃. The low viscosity of the salts (4.85 cP at 298 K for EMIF·2.3HF) is essential to the high ionic conductivity of these salts.