Revisiting the mechanism of β-O-4 bond cleavage during acidolysis of lignin. Part 1: Kinetics of the formation of enol ether from non-phenolic C6-C2 type model compounds
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Tomoya Yokoyama
Abstract
The reaction route of a dimeric non-phenolic C6-C2 type lignin model compound, 2-(2-methoxyphenoxy)-1-(3,4-dimethoxyphenyl)ethanol (VIII), was kinetically examined under acidolysis conditions (0.2 mol l-1 HBr in 82% aqueous 1,4-dioxane at 85°C). The disappearance of (VIII) followed the pseudo-first-order rate law, and the rate constant k(VIII) was 0.00854. In the course of the reactions, the following compounds were produced quantitatively at any time: an enol ether, 1-(2-methoxyphenoxy)-2-(3,4-dimethoxyphenyl)ethylene (IX), 2-methoxyphenol (X), and a Hibbert's ketone, 3,4-dimethoxyphenylacetaldehyde (XI). The substances (X) and (XI) are the result of the β-O-4 bond cleavage and their amounts were always equal during the whole reaction. When (IX) was subjected to the acidolysis under the identical conditions, its disappearance followed the pseudo-first-order rate law, and the rate constant k(IX) was 0.00825. Furthermore, (VIII) was not observed at all, and (X) was produced quantitatively at any time. Based on these results, the formation rate of (IX) during the acidolysis of (VIII) is expressed by the equation: d[(IX)]/dt=A·k(VIII)[(VIII)]-k(IX)[(IX)], where A is the proportion of (VIII) that converted into (IX) when (VIII) degraded. It was confirmed by solving this differential equation that the formation and disappearance of (IX) is best simulated when A was assumed to be 1.00. Therefore, it was proven in this paper for the first time that (VIII) primarily converts into (IX), and subsequently the β-O-4 bond cleavage occurs and (X) and (XI) are yielded.
©2008 by Walter de Gruyter Berlin New York
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- Development of fully bio-based composite: Wood/cellulose diacetate/poly(lactic acid) composite
- Crystallinity and mesoporosity of carbon produced from ligno-p-cresol and their improvement by pulverization and acid treatment
- Revisiting the mechanism of β-O-4 bond cleavage during acidolysis of lignin. Part 1: Kinetics of the formation of enol ether from non-phenolic C6-C2 type model compounds
- Study of kinetics of reaction of lignin model compounds with propylene oxide
- Two-dimensional homo- and hetero-correlation technique applied to NIR and py-MBMS spectra of wood
- UV resonance Raman spectroscopic study of photodegradation of hardwood and softwood lignins by UV laser
- A multivariate approach to the acetylated poplar wood samples by near infrared spectroscopy
- Structure elucidation of phenylethanoid glycosides from Paulownia tomentosa Steud. var. tomentosa wood
- A generalized mat consolidation model for wood composites
- Prediction and optimization of surface roughness in milling of medium density fiberboard (MDF) based on Taguchi orthogonal array experiments
- An investigation on the permeability of different wood furnish materials
- Laccase-catalyzed functionalization with 4-hydroxy-3-methoxybenzylurea significantly improves internal bond of particle boards
- Effect of thermo-mechanical refining pressure on the properties of wood fibers as measured by nanoindentation and atomic force microscopy
- Adhesive bond strength of end grain joints in softwood with varying density
- An experimental study of the effects of moisture variations and gradients in the joint area in steel-timber dowel joints
- A new image analysis algorithm for calculating percentage wood failure
- Dr. Gordon Leary
Articles in the same Issue
- Meetings
- Cellulose aerogels: Highly porous, ultra-lightweight materials
- Esterification of carboxylic acids on cellulosic material: Solid state reactions
- Bagasse alkaline sulfite-anthraquinone (AS/AQ) pulping and totally chlorine free (TCF) bleaching
- Effect of abnormal fibres on the mechanical properties of paper made from Norway spruce, Picea abies (L.) Karst.
- Development of fully bio-based composite: Wood/cellulose diacetate/poly(lactic acid) composite
- Crystallinity and mesoporosity of carbon produced from ligno-p-cresol and their improvement by pulverization and acid treatment
- Revisiting the mechanism of β-O-4 bond cleavage during acidolysis of lignin. Part 1: Kinetics of the formation of enol ether from non-phenolic C6-C2 type model compounds
- Study of kinetics of reaction of lignin model compounds with propylene oxide
- Two-dimensional homo- and hetero-correlation technique applied to NIR and py-MBMS spectra of wood
- UV resonance Raman spectroscopic study of photodegradation of hardwood and softwood lignins by UV laser
- A multivariate approach to the acetylated poplar wood samples by near infrared spectroscopy
- Structure elucidation of phenylethanoid glycosides from Paulownia tomentosa Steud. var. tomentosa wood
- A generalized mat consolidation model for wood composites
- Prediction and optimization of surface roughness in milling of medium density fiberboard (MDF) based on Taguchi orthogonal array experiments
- An investigation on the permeability of different wood furnish materials
- Laccase-catalyzed functionalization with 4-hydroxy-3-methoxybenzylurea significantly improves internal bond of particle boards
- Effect of thermo-mechanical refining pressure on the properties of wood fibers as measured by nanoindentation and atomic force microscopy
- Adhesive bond strength of end grain joints in softwood with varying density
- An experimental study of the effects of moisture variations and gradients in the joint area in steel-timber dowel joints
- A new image analysis algorithm for calculating percentage wood failure
- Dr. Gordon Leary
