Wood and other lignocellulosic materials are formed by
three main polymeric constituents, cellulose, lignin, and
hemicelluloses [25]. Cellulose is a linear and highly ordered
(often crystalline) polymer of cellobiose (D-glucopyranosyl-
β-1,4-D-glucopyranose) that represents over 50% of wood
weight. By contrast, lignin is a three-dimensional network
built up of dimethoxylated (syringyl, S), monomethoxylated
(guaiacyl, G) and non-methoxylated (p-hydroxyphenyl, H)
phenylpropanoid units, derived from the corresponding p-hydroxycinnamyl
alcohols, which give rise to a variety of subunits
including different ether and C—C bonds. Acetylated
lignin units have been recently identified in non-woody plants
using analytical pyrolysis