Properties and Potential Utilization of Industrial Eucalyptus Soda/Anthraquinone Lignin Part II. Properties of the Purified Lignin

Klashorst, G. H. Van Der; Strauss, Heinrich F.

doi:10.1515/hfsg.1987.41.3.185

Cited by 4 publications

(1 citation statement)

References 7 publications

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“…The number of aromatic sites reactive towards base catalyzed electrophilic substitution reactions, therefore, is fairly low at about 0.3 per C9 unit (Table II). The soda/AQ hardwood lignin is constituted of both guaiacyl (2) and syringylpropanoid (3) units, of which the former have been condensed extensively during pulping (17). This is indicated by the low number of unsubstituted 5-positions (Table II).…”

Section: Meta Hydroxymethylationmentioning

confidence: 99%

Modification of Lignin at the 2- and 6-Positions of the Phenylpropanoid Nuclei

Klashorst

1989

ACS Symposium Series

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Lignin model compounds were reacted with formaldehyde in acid medium at positions meta to the aromatic hydroxy groups. Both phenolic and etherified phenolic lignin model compounds were shown to give fast polymerization or hydroxymethylation of the meta positions depending on the conditions used. This reaction differs from the reaction of formaldehyde with phenolic lignin model compounds under alkaline conditions, where the reaction with formaldehyde always occurs at positions ortho/para to the aromatic hydroxy group. The conditions developed for the polymerization and hydroxymethylation were also evaluated on industrial lignin. The reaction of formaldehyde with the meta positions of lignin clearly have considerable potential for the use of lignin, particularly heavily condensed alkali lignin, in polymeric applications.Lignin, present as a waste material in the spent liquors of the pulping industry, constitutes a potentially useful raw material for the production of various polymeric products. This has repeatedly been demonstrated in the past by its application in products ranging from wood adhesives to plastics (1). In these applications the lignin is crosslinked to increase its molecular mass or to form a rigid three-dimension ally crosslinked structure.The features on lignin that were utilized for these polymerization or modification reactions are as follows (compare Fig. 1):1. phenolic hydroxy group; 2. aliphatic hydroxy group; 3. unsubstituted 3-or 5-positions on C9 units; and 4. structures that can form quinonemethide intermediates.

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Section: Meta Hydroxymethylationmentioning

confidence: 99%