A Discover system microwave apparatus (CEM, Matthews, NC, USA) was used for the assistance in synthesis of ionic liquid. The procedure for ionic liquid synthesis is diagrammed in Fig. 1.A mixture of 1-methylimidazole (0.0123 mmol) and n-butyl chloride (0.0135 mmol) was heated in a round-bottom flask with microwave energy for 5 min at a power of 30 W and temperature of 70 C, then the whole