A Concise and Efficient Synthesis of Novel Alkylated 2-(2-hydroxyphenyl)-4,5-diphenyiimidazole-based Sonic Liquids Using the MAOS Technique

摘要

Given the desirable outcomes to organic synthesis afforded by the use of ionic liquids1"4 there is a need for the development of more efficient techniques for their preparation. The microwave-assisted organic synthesis technique (MAOS) has been recently utilized for preparing ILs.5'6 MAOS provides faster, easier, and less expensive synthesis processes.5'7"10 The rate of reaction can be significantly increased with MAOS because it provides homogeneous heating and a dielectric effect directly into the reacting compounds.5'9'11'12 We now report an efficient MAOS technique for the preparation of the novel ILs l,3-dipropyl-2-(2-butoxyphenyl)-4.5-diphenylimidazole iodide (DPDImI) (1) and l,3-dibutyl-2-(2-butoxyphenyl)-4.5-diphenylimidazole iodide (DBDImI) (2). We were interested in preparing these ionic liquids because the lipophilic side chains would potentially impart greater hydrophobic character to the ILs. In addition, we aimed to apply the ILs as green solvents for biomass conversions6 and corrosion inhibitors which required highly hydrophobic properties. Our preparation (Scheme 1) affords the new ILs in high yields without the need for excessive purification. It is based on the use of the readily available and inexpensive starting material benzil.