Synthesis, Characterization, and Crystal Structure of Several Novel Acidic Ionic Liquids: 1-ethyl-2-alkyl-benzimidazolium Tetra-Fluoroborate
A series of novel acidic ionic liquid: 1-ethyl-2-alkyl-benzimidazolium tetra-fluoroborate (alkyl= Et, Pr-n, Bu-n) were prepared by simple acid-based neutralization of 1-ethyl-2-alkyl-benzimidazole and tetrafluoroboric acid. The compounds were characterized by FTIR spectra, elemental analysis,1HNMR spectra and thermogravimetric analysis. These novel tetra-fluoroborate salts show good catalytic activity to esterification of benzyl alcohol and acetic acid. Furthermore, a crystal of ([H-ebBiBF4) was prepared with the crystal structure and determined by X-ray diffraction analysis. The molecular is of lamellar structure as mainly π electron ring is stacked interleaving between two layers. The results of cation and anion arranged orderly in pair indicate that the coulombic attraction is more dominant. Simultaneously, the weak local hydrogen bonds C-H···F exist in the molecules.