title: Structural characterization of hemicelluloses and topochemical changes in Eucalyptus cell wall during alkali ethanol treatment.
abstract: Eucalyptus was sequentially extracted with 70% ethanol containing 0.4, 1.0, 2.0, 3.0, and 5.0% NaOH for 2h at 80°C. The chemical composition and structural features of the hemicellulosic fractions obtained were comparatively characterized by the combination of high-performance anion-exchange chromatography, gel permeation chromatography, Fourier transform infrared, and nuclear magnetic resonance spectroscopies. Furthermore, the main component distribution and their changes in cell wall were investigated by confocal Raman microscopy. Based on the Fourier transform infrared and nuclear magnetic resonance analyses, the hemicelluloses extracted from Eucalyptus mainly have a linear backbone of (1→4)-linked-β-d-xylopyranosyl residues decorated with branch at O-2 of 4-O-methyl-α-glucuronic acid unit. Raman analysis revealed that the dissolution of hemicelluloses was different in the morphological regions, and the hemicelluloses released mainly originated from the secondary wall. The information obtained from the study conducted by combining chemical characterization with ultrastructure provides important basis for studying the mechanism of the alkali treatment.
authors.affiliation: Beijing Key Laboratory of Lignocellulosic Chemistry, College of Material Science and Technology, Beijing Forestry University, Beijing 100083, China.
authors.forename: Han-Yin
authors.initials: HY
authors.lastname: Li
authors.affiliation: Beijing Key Laboratory of Lignocellulosic Chemistry, College of Material Science and Technology, Beijing Forestry University, Beijing 100083, China.
authors.forename: Shao-Ni
authors.initials: SN
authors.lastname: Sun
authors.affiliation: Beijing Key Laboratory of Lignocellulosic Chemistry, College of Material Science and Technology, Beijing Forestry University, Beijing 100083, China.
authors.forename: Xia
authors.initials: X
authors.lastname: Zhou
authors.affiliation: Beijing Key Laboratory of Lignocellulosic Chemistry, College of Material Science and Technology, Beijing Forestry University, Beijing 100083, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Peng
authors.affiliation: Beijing Key Laboratory of Lignocellulosic Chemistry, College of Material Science and Technology, Beijing Forestry University, Beijing 100083, China. Electronic address: rcsun3@bjfu.edu.cn.
authors.forename: Run-Cang
authors.initials: RC
authors.lastname: Sun
mesh_terms: D002473:Cell Wall / Q000737:chemistry; D000431:Ethanol / Q000737:chemistry*; D005052:Eucalyptus / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008970:Molecular Weight; D011134:Polysaccharides / Q000737:chemistry*; D012972:Sodium Hydroxide / Q000737:chemistry*; D012995:Solubility; D017550:Spectroscopy, Fourier Transform Infrared; D013059:Spectrum Analysis, Raman; D014934:Wood / Q000737:chemistry
chemical_list: D011134:Polysaccharides; D000431:Ethanol; D012972:Sodium Hydroxide; C007916:hemicellulose
keywords: Confocal Raman microscopy; Eucalyptus; Hemicelluloses; Structural characterization; Successive alkali ethanol treatment