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Japanese cedar ( Cryptomeria japonica) was treated with the ionic liquid (IL) 1-ethyl-3-methylimidazolium chloride ([C2mim][Cl]), which is a solvent for cellulose, and the changes in the chemical components and their distribution in wood cell walls have been investigated by Raman microscopy. Raman spectra, recorded from various areas of the cell walls, showed that lignin in the compound middle lamellae (CML) and cell corners (CC) was resistant to the reaction with [C2mim][Cl], but its molecular structure changed partially. The reactivity of cellulose and hemicelluloses with [C2mim][Cl] was higher than that of lignin in the cell wall, and the cell wall structure was maintained even in an advanced state of the reactions. The effects of [C2mim]-[Cl] on cellulose and hemicelluloses in the cell wall were homogeneous, whereas that of lignin was inhomogeneous. [ABSTRACT FROM AUTHOR]

Western red cedar and Japanese beech are studied concerning their liquefaction behavior with an ionic liquid, 1-ethyl-3-methylimidazolium chloride ([C2mim][Cl]). Significant differences in liquefaction behavior were observed in terms of solubility and the lignin content of the insoluble residues. Thioacidolysis analysis of the residues confirmed that β-O-4 bonds in lignin were cleaved preferentially by the treatment with [C2mim][Cl]. The differences in liquefaction behavior can be explained by structural differences between softwood and hardwood lignins. Furthermore, gel permeation chromatography and GC-MS analyses revealed that cellulose and hemicelluloses were decomposed partly to monomeric sugars such as glucose, mannose, galactose, xylose, and arabinose. [ABSTRACT FROM AUTHOR]