Side reactions of 4-acetamido-TEMPO as the catalyst in cellulose oxidation systems
-
Ilabahen Patel
Abstract
TEMPO/hypochlorite oxidation of cellulosics are frequently used to obtain water-soluble polyglucuronates or nano-disperse materials. The reaction under neutral conditions offers a big advantage over hitherto applied alkaline systems as base-induce β-elimination reactions causing severe cellulose degradation are suppressed. Although 4-acetamido-TEMPO seems to offer high initial activities in cellulose oxidation, the TEMPO derivative is irreversibly converted into species with much lower reactivity. The degradation pathways and the chemical structure of the 4-acetamido-TEMPO-derived (by)products have been clarified. Degradation is strongly dependent on the pH value of the reaction mixture. In acidic conditions (pH<5), 4-oxo-TEMPO is formed by an oxidative deamination process, the 4-oxo-derivative still being capable of performing cellulose oxidation. In alkaline media, a similar process proceeds, but is immediately followed by a Favorskij rearrangement to a pyrrolidine-3-carboxylic acid (PROXYL) derivative. In both cases, the released acetamido moiety is slowly converted into methylamine by a decarboxylative rearrangement (Hofmann degradation). The results suggest that the instability and the chemical fate of 4-acetamido-TEMPO needs to be considered when cellulose oxidations and their kinetics are addressed: the recyclability of the 4-acetamido-TEMPO catalyst is rather limited.
©2010 by Walter de Gruyter Berlin New York
Articles in the same Issue
- Original papers
- Side reactions of 4-acetamido-TEMPO as the catalyst in cellulose oxidation systems
- Reactions of aldehydes with chlorous acid and chlorite in chlorine dioxide bleaching
- Using cationic polyvinyl alcohol (C-PVA) to improve the strength of wood-free papers containing high-yield pulp (HYP)
- A new phenolic glucoside and flavonoids from the bark of Eucommia ulmoides Oliv.
- Decomposition of a phenolic lignin model compound over organic N-bases in an ionic liquid
- Investigation on wax-impregnated wood. Part 1: Microscopic observations and 2D X-ray imaging of distinct wax types
- Investigation on wax-impregnated wood. Part 2: Study of void spaces filled with air by He pycnometry, Hg intrusion porosimetry, and 3D X-ray imaging
- Surface properties of eucalyptus pulp fibres as reinforcement of cement-based composites
- Cure kinetics of PF/PVAc hybrid adhesive for manufacturing profiled wood-strand composites
- Moisture induced stresses perpendicular to the grain in glulam: Review and evaluation of the relative importance of models and parameters
- Three-dimensional modeling of the structure formation and consolidation of wood composites
- Observation of cell shapes in wood cross-sections during water adsorption by confocal laser-scanning microscopy (CLSM)
- A single cell model for pretreatment of wood by microwave explosion
- Pore space analysis of beech wood: The vessel network
- Quantification of fungal colonization in modified wood: Quantitative real-time PCR as a tool for studies on Trametes versicolor
- Copper monoethanolamine adsorption in wood and its relation with cation exchange capacity (CEC)
- Effect of amine ligand, copper/amine ratio, and pH on copper adsorption into wood
- Effect of different soils and pH amendments on brown-rot decay activity in a soil block test
- A proposed accelerated field stake test for rapid assessment of wood preservative systems
- Meetings
- Meetings
Articles in the same Issue
- Original papers
- Side reactions of 4-acetamido-TEMPO as the catalyst in cellulose oxidation systems
- Reactions of aldehydes with chlorous acid and chlorite in chlorine dioxide bleaching
- Using cationic polyvinyl alcohol (C-PVA) to improve the strength of wood-free papers containing high-yield pulp (HYP)
- A new phenolic glucoside and flavonoids from the bark of Eucommia ulmoides Oliv.
- Decomposition of a phenolic lignin model compound over organic N-bases in an ionic liquid
- Investigation on wax-impregnated wood. Part 1: Microscopic observations and 2D X-ray imaging of distinct wax types
- Investigation on wax-impregnated wood. Part 2: Study of void spaces filled with air by He pycnometry, Hg intrusion porosimetry, and 3D X-ray imaging
- Surface properties of eucalyptus pulp fibres as reinforcement of cement-based composites
- Cure kinetics of PF/PVAc hybrid adhesive for manufacturing profiled wood-strand composites
- Moisture induced stresses perpendicular to the grain in glulam: Review and evaluation of the relative importance of models and parameters
- Three-dimensional modeling of the structure formation and consolidation of wood composites
- Observation of cell shapes in wood cross-sections during water adsorption by confocal laser-scanning microscopy (CLSM)
- A single cell model for pretreatment of wood by microwave explosion
- Pore space analysis of beech wood: The vessel network
- Quantification of fungal colonization in modified wood: Quantitative real-time PCR as a tool for studies on Trametes versicolor
- Copper monoethanolamine adsorption in wood and its relation with cation exchange capacity (CEC)
- Effect of amine ligand, copper/amine ratio, and pH on copper adsorption into wood
- Effect of different soils and pH amendments on brown-rot decay activity in a soil block test
- A proposed accelerated field stake test for rapid assessment of wood preservative systems
- Meetings
- Meetings
