New hydrophobic ionic liquids based on perfluoroalkyltrifluoroborate anions

New hydrophobic ionic liquids, 1-ethyl-3-methylimidazolium (EMI+) perfluoroalkyltrifluoroborate ([RfBF3](-)) (R-f = C2F5, n-C3F7, and n-C4F9) were prepared in high yield and purity by facile neutralization of 1-ethyl-3-methylimidazolium (EMI+) methylcarbonate (MeOCO2-) with aqueous H-solv.[RfBF3](solv.) solutions. All the salts prepared were characterized by F-19, H-1, B-11 NMR, MS and elemental analysis, and thermal and electrochemical properties of these salts have been measured. [EMI][C2F5BF3] melted at lower temperature (-1 degreesC) than [EMI][BF4] (13 degreesC), resulting in higher conductivity at low temperature. Its application to double-layer capacitors (DLCs) was examined. (C) 2003 Elsevier B.V. All rights reserved.