Investigation of carbon-2 substituted imidazoles and their corresponding ionic liquids

The functionality at the C-2 position of the imidazole ring plays a key role in defining the chemical properties of the imidazoles and their corresponding ionic liquids. Imidazoles 1−6 with different C-2 functionality were synthesized and their corresponding ionic liquids were systematically investigated. Based on their physical properties the six imidazoles can be divided into three groups. (1) The imidazoles 2 and 3 are capable of self-polymerization to form poly(ionic liquid)s, and they are characterized with a strong leaving group at the C-2 position. (2) The imidazoles 4 and 5 can form ionic liquids, but they are very sensitive to moisture. (3) The imidazoles 1 and 6 can form stable ionic liquids, and their stabilities were influenced by the electronic effects of the substituents at the C-2 position.