Preparation of novel room-temperature molten salts by neutralization of amines

Examples of a new class of onium salts bearing the tetrafluoroborate anion (BF4-) were prepared by neutralization of the corresponding amines. This method greatly simplifies the preparation of many organic molten salts. Some of the resulting neutralized amines displayed an ionic conductivity greater than 10(-2) S cm(-1) at room temperature. The largest ionic conductivity was observed in 2-methyl-1-pyrroline neutralized by HBF4. In addition, the ionic conductivity above the melting point is well described by the Vogel-Tamman-Fulcher formula. There is a correlation between the ionic conductivity of neutralized amines and of the corresponding alkylated onium salts having the same heteroaromatic rings. These neutralized amines are convenient models of onium salts having high ionic conductivity. (C) 2000 The Electrochemical Society. S0013-4651(00)03-120-7. All rights reserved.