Comparative Studies on Synthesis of Imidazole Ionic Liquids and Their Solubility for Wood by Microwave

The present work deals with the synthesis of various imidazole ionic liquids [BMIM]Cl, [AMIM]Cl, [AEIM]Cl, [HeEIM]Cl and [HeVIM]Cl, the chemical structures of ionic liquids by FTIR and 1HNMR, the pretreatment of wood powder as extracted with a mixture of benzene/ethanol or activated with 25% (mass fraction) NaOH under normal temperature and pressure, microwave and high pressure, studies the solubility of ionic liquids on the wood powder by microwave (90°C, 400w), and analyses the microstructure of the wood before and after dissolution as measured by SEM. The result shows that all the ionic liquids can dissolve the wood fiber directly, ionic liquids containing hydroxyl group exhibit better solubility. Wood powder pretreated with 25% NaOH under high pressure has the lowest crystallinity (2.4%) and the highest dissolution rate. The solubility of [HeVIM]Cl is the best, which approach to 21.6%.