Zur Kenntnis der Carbonylgruppen im Lignin. I.

Adler, Erich; Marton, Josef; Smith-Kielland, I.; Sömme, R.; Stenhagen, Einar; Palmstierna, H.

doi:10.3891/acta.chem.scand.13-0075

Cited by 85 publications

(19 citation statements)

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“…The content of cinnamaldehyde units in spruce-milled wood lignin is around 4 per 100 C 9 -units (one phenolic and three etherified). Approximately the same amount is found in unbleached softwood groundwood pulp (Adler and Marton 1959;Marton et al 1961;Hirashima and Sumimoto 1987;Brunow and Lundquist 2010). Cinnamaldehydes are efficiently sulfonated by sodium sulphite (CTMP-production) and are degraded during alkaline hydrogen peroxide-bleaching although, in industrial practice, probably not completely Hirashima and Sumimoto 1987;Suckling 1991;Gellerstedt and Zhang 1992;Lundquist et al 2007).…”

Section: Other Reactionsmentioning

confidence: 95%

Review: Light-Induced Yellowing of Lignocellulosic Pulps – Mechanisms and Preventive Methods

Paulsson¹,

Parkås²

2012

BioResources

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This review will focus on recent progress regarding the mechanisms of light-induced discoloration of mechanical and chemimechanical pulps and on the proposed preventive treatments. It is evident that the mechanisms behind photoyellowing of lignin-rich pulps are complex and that several types of reaction pathways may coexist. Photoyellowing proceeds via one initial fast phase and a slower following phase. The fast phase has been ascribed to oxidation of free phenolic groups and/or hydroquinones and catechols to photoproducts of mainly quinonoid character. A multitude of reactions involving several lignin subunits are possible. Important intermediates are phenoxyl radicals, and to some extent ketyl radicals. The importance of the phenacyl aryl ether pathway might be more important than previously thought, even though the original content of such groups is low in lignin. Even though many preventive methods against photoyellowing have been suggested, no cost-efficient treatment is available to hinder photoreversion of lignincontaining paper permanently. Suggested methods for stabilization include chemical modification (etherification and esterification), coating the paper product, addition of radical scavengers, excited state quenchers, or ultraviolet absorbing compounds.

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Section: Other Reactionsmentioning

confidence: 95%

Review: Light-Induced Yellowing of Lignocellulosic Pulps – Mechanisms and Preventive Methods

Paulsson¹,

Parkås²

2012

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“…Les (Leary, 1968 Le rôle des phénols dans la photodégra-dation des lignines n'est pas encore clairement élucidé (Castellan et al, 1990;Heitner et Schmidt, 1991). L'étude de la photolyse en solution des molécules modèles des lignines a montré que la pré-sence de groupes phénoliques libres n'est pas nécessaire pour induire une forte coloration (Scalbert et al, 1987); -la structure des lignines : la structure des lignines de feuillus contient un nombre plus important d'unités syringyles (Nimz, 1974) alors qu'il y a beaucoup plus de gaïacyls pour les résineux (Adler et Marton, 1959;Adler, 1977 (Hon et Ifju, 1978 (Wengert, 1968;Schmitt, 1984 (Dirckx, 1988 (Bergman, 1969) (Dirckx, 1988;Dirckx et al, 1992) …”

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Modification de couleur du bois de chênes européens exposés à la lumière solaire

Mazet¹,

Triboulot-Trouy²,

Merlin³

et al. 1993

Ann. For. Sci.

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(fig 22) to take into account the discoloration of wood under solar-type light exposure at the molecular level. In this paper, this model was extended to European species of oak (Quercus robur and petraea) with high levels of colored extractable substances and for which the color characteristics are a quality criterion. In addition to the observed and analyzed yellowing in Abies grandis wood, a color lightening corresponding to a lowered absorption over the spectral range (500-600 nm) (figs 2, 6) has been observed. Lignin photodegradation is certainly in part responsible for this decoloration. It has also been shown that oak sapwood and heartwood undergo different kinds of photodecoloration (fig 3). For color photostabilization of oak wood under solar light, the results indicate that it is necessary to use UV absorbers to lower the yellowing due to UV light and antioxidants to inhibit color lightening due to reactions with oxygen.

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“…By the reduction of OLC and LCO with NaBH 4 , only a weak band remains around 1720 cm -1 due to the slow reactivity of the unconjugated carbonyl groups (Fig. 4D, F) [7,8,9]. …”

Section: Structural Characterization Of Lignophenolsmentioning

confidence: 99%

Response of lignophenols for oxidation and reduction systems

Horii

Funaoka

2009

Trans. Mat. Res. Soc. Japan

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Lignin is one of the most abundant renewable materials. It has perfect biodegradability in soil. This biodegradation proceeds oxidatively and reductively. In order to utilize along the material flow in the ecosystem, it is important to obtain information for oxidative and reductive responses of lignophenols, which were synthesized through the phase-separation system. Lignocresol was synthesized from Hinoki cypress (Chamaecyparis obtusa) through the phase-separation system with 72% H 2 SO 4 and p-cresol. Responses under both oxidation and reduction environments were estimated by FT-IR, TGA and TMA. Both lignocresol and wood meals were oxidized with sodium periodate. FT-IR spectra of oxidized lignocresol indicated the formation of muconic acid type structures. FT-IR spectra of lignocresol derived from oxidized wood meals indicated the phenolation of conjugated carbonyl structures. Thermal stability of lignophenols was improved by the reduction treatments with sodium borohydride.

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Zur Kenntnis der Carbonylgruppen im Lignin. I.

Cited by 85 publications

References 0 publications

Review: Light-Induced Yellowing of Lignocellulosic Pulps – Mechanisms and Preventive Methods

Review: Light-Induced Yellowing of Lignocellulosic Pulps – Mechanisms and Preventive Methods

Modification de couleur du bois de chênes européens exposés à la lumière solaire

Response of lignophenols for oxidation and reduction systems

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