Microwave-assisted conversion of microcrystalline cellulose to 5-hydroxymethylfurfural catalyzed by ionic liquids.

Ionic liquid (IL) has been widely investigated in 5-HMF production from biomass. However, most of studies employed IL as reaction solvent which requires a large amount of IL. In the present study, IL was utilized as catalyst in the conversion of microcrystalline cellulose (MCC) to 5-HMF under microwave irradiation (MI) in N,N-dimethylacetamide (DMAc) containing LiCl. 1,1,3,3-tetramethylguanidine (TMG)-based ILs, including 1,1,3,3-tetramethylguanidine tetrafluoroborate ([TMG][BF4]) and 1,1,3,3-tetramethylguanidine lactate ([TMG]L) which were commonly used in the absorption of SO2 and CO2 from flue gas, were synthesized and applied in the conversion of MCC to 5-HMF for the first time. Of the catalysts employed, [TMG]BF4 showed high catalytic activity in 5-HMF production from MCC. The condition including the ratio of IL to MCC, temperature and time for MCC conversion was optimized using Central Composite Design (CCD) and Response Surface Methodology (RSM). The highest 5-HMF yield of 28.63% was achieved with the optimal condition.