Structural Differences between the Lignin−Carbohydrate Complexes Present in Wood and in Chemical Pulps

• Published in: Biomacromolecules Vol. 6; no. 6; pp. 3467 - 3473
• Main Authors: Lawoko, Martin, Henriksson, Gunnar, Gellerstedt, Göran
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.11.2005
• Subjects: Acetone - chemistry; Acetylation; Applied sciences; Biocompatible Materials - chemistry; BONDS; Carbohydrate Conformation; Carbohydrates - chemistry; Cellulase; Cellulosa- och pappersteknik; Cellulose and paper engineering; Chemical engineering; Chemical process and manufacturing engineering; Chromatography; Chromatography, Gel; CONDENSATION; COOKING; Dimerization; Exact sciences and technology; Kemisk process- och produktionsteknik; Kemiteknik; Lignin - chemistry; Lignin and derivatives; Macromolecular Substances; Models, Chemical; Molecular Structure; Molecular Weight; Natural polymers; Oxygen - chemistry; Phenol - chemistry; Physicochemistry of polymers; Polymers - chemistry; Protein Binding; RESIDUAL LIGNIN; SOFTWOOD KRAFT PULP; SPRUCE LIGNIN; TECHNOLOGY; TEKNIKVETENSKAP; THIOACIDOLYSIS; Time Factors; Wood; Xylans - chemistry; Lignin; Molecular structure; Paper pulp; Oside polymer; Softwood; Chemical composition; Experimental study; Comparative study
• ISSN: 1525-7797; 1526-4602; 1526-4602
• DOI: 10.1021/bm058014q

Lignin−carbohydrate complexes (LCCs) were prepared in quantitative yield from spruce wood and from the corresponding kraft and oxygen-delignified pulps and were separated into different fractions on the basis of their carbohydrate composition. To obtain an understanding of the differences in lignin structure and reactivity within the various LCC fractions, thioacidolysis in combination with gas chromatography was used to quantify the content of β-O-4 structures in the lignin. Periodate oxidation followed by determination of methanol was used to quantify the phenolic hydroxyl groups. Furthermore, size exclusion chromatography (SEC) of the thioacidolysis fractions was used to monitor any differences between the original molecular size distribution and that after the delignification processes. Characteristic differences between the various LCC fractions were observed, clearly indicating that two different forms of lignin are present in the wood fiber wall. These forms are linked to glucomannan and xylan, respectively. On pulping, the different LCCs have different reactivities. The xylan-linked lignin is to a large extent degraded, whereas the glucomannan-linked lignin undergoes a partial condensation to form more high molecular mass material. The latter seems to be rather unchanged during a subsequent oxygen-delignification stage. On the basis of these findings, a modified arrangement of the fiber wall polymers is suggested.