Guaiacyl and Syringyl Lignin Composition in Hardwood Cell Components

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Abstract
Summary Vessels White oak cell types, fibers, rays, and vessels, were isolated from high-yield chemimechanical, neutral Rays sulphite semichemical (NSSC), and kraft pulps. Milled wood lignins (MWL) from NSSC fiber and ray Fibers cell fractions analyzed by ultraviolet and infrared spectroscopy were found to have similar syringyl/ Cell wall guaiacyl ratios. Methoxyl analyses of MWL's were also similar and, upon comparison to the methoxyl Middle lamella contents of their Klason lignins and of Klason lignins from pulp fractions, it was found that the Hardwoods methoxyl analyses of the Klason lignins from wood and pulp fractions were representative of actual Milled wood lignins lignin methoxyl content. A middle lamella enriched lignin fraction was obtained by refining of the Nitrobenzene oxidation fibers; cell wall lignin-enriched fractions were obtained by selective removal of middle lamella lignin Methoxyl by oxygen and acid chlorite as shown by ultraviolet microscopy. These lignin fractions had similar High-yield pulp methoxyl contents indicating the relatively uniform syringyl/guaiacyl ratio of lignin in different Absorption spectra (UV, IR) morphological regions. Methoxyl analysis of intact vessels isolated from an oak NSSC pulp gave White oak unambiguous proof of the syringyl/guaiacyl nature of hardwood vessel lignin. The occurrence of typical syringyl/guaiacyl ratios throughout the wood was also indicated for birch and ash. Schlüsselwörter Die Verteilung von Guaiacyl- und Syringyl-Lignin-Baueinheiten in den Zellarten bei Laubhölzern (Sachgebiete) Lignin Zusammenfassung