Chemical and structural characterization of alkaline‐extractable hemicelluloses from various eucalyptus species

Eucalyptus species are currently one of the main feedstock for pulping and papermaking industry in China. In the present study, alkali‐extractable hemicelluloses were isolated from different eucalyptus species (Eucalyptus camaldulensis, E. urophylla × grandis, and E. urophylla × E. tereticornis) at mild conditions prior to pulping. Structural characterization of these hemicellulosic polymers based on monosaccharide, molecular weight, Fourier transform infrared, ¹H, ¹³C, and two‐dimensional heteronuclear single quantum coherence nuclear magnetic resonance analysis revealed that these alkali‐extractable polysaccharides shared the common structure composed of the (1→4)‐linked‐β‐D‐xylopyranosyl backbone with 4‐O‐methyl‐α‐D‐glucuronic acid attached to O‐2 of the xylose residues. The potential structures of the alkali‐extractable hemicelluloses were proposed based on the comprehensive analysis. The well‐characterized structures of these hemicelluloses could enlarge the industrial application of these hemicelluloses from the Eucalyptus species in a biorefinery process. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2390–2398, 2013