Zur Oxydation von14C-markierten Phenolen (Ligninmodellen) in wäßrig-alkalischer Lösung mit Sauerstoff

Kratzl, K.; Schäfer, Wolfram; Claus, P.; Gratzl, Josef S.; Schilling, P.

doi:10.1007/bf00901392

Cited by 31 publications

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“…Although this can be explained by the Dakin-like (Dakin 1901) and Baeyer-Villiger (Bouillon et al 1983) reactions, it most likely arises from the elimination of acetic acid or acetaldehyde respectively, via the addition of ΗΟΟ·/·Ο 2~ and subsequent Reverse Aldol Addition (Kratzl et al 1967 Figure 4 shows the rate of formation of methoxyhydroquinone C4 (+) during the degradation of acetoguaiacone (O). Also include is the degradation of C4 in identical conditions.…”

Section: Reaction Of Cyanamide-peroxide With Apocynol and Acetoguaiaconementioning

confidence: 97%

“…Furthermore C4 (+) is only generated after the majority of acetoguaiacone (O) and hydrogen peroxide (x) are degraded. Therefore, it is likely that the generation of C4 arises from the reduction of methoxy-/?-quinone, generated as per Kratzl et al (1967), by various hydroxylated intermediates (Gellerstedt et al 1980).…”

Section: Reaction Of Cyanamide-peroxide With Apocynol and Acetoguaiaconementioning

confidence: 99%

“…In any reaction system involving phenoxyl radicals, oxidative coupling, in particular dimerization, will be expected to occur and is evident by the presence of oc-5, 4-O-5 and 5-5' bicreosol. The nature of the dimerization process has been discussed by Kratzl et al (1966Kratzl et al ( , 1967 and consists of phenoxyl/benzyl radical coupling followed by aromatization. These dimeric compounds are known to react under alkaline conditions in the presence of hydrogen peroxide degradation products and molecular oxygen (Kratzl et al 1966).…”

Section: Reaction Of Cyanamide-peroxide With Creosolmentioning

confidence: 99%

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Reactions of Lignin with Cyanamide Activated Hydrogen Peroxide. Part 2. The Degradation Mechanism of Phenolic Lignin Model Compounds

Kadla¹,

Chang²,

Chen³

et al. 1998

Holzforschung

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The reactions of monomeric phenolic lignin model compounds with cyanamide activated hydrogen peroxide were studied. Analyses of the various reaction products indicate four main reactions occur; aromatic hydroxylation, demethoxyiation, radical coupling and oxidative ring opening. The predominate products from apocynol and acetoguaiacohe were dicarboxylic acid compounds, maleic/fumaric, oxalic, and succinic acid derivatives, consistent with degradation by Superoxide. In the degradation of creosol, 3-hydroxy-4-methoxy-6-methyl-N-methylaniline was the major compound isolated, providing evidence of a cyanamide radical. Finally, plausible pathways to the formation of Superoxide anion and cyanamide oxidation products from alkaline hydrogen peroxide and cyanamide are proposed and their impact on delignification is discussed.

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Section: Reaction Of Cyanamide-peroxide With Apocynol and Acetoguaiaconementioning

confidence: 97%

Section: Reaction Of Cyanamide-peroxide With Apocynol and Acetoguaiaconementioning

confidence: 99%

Section: Reaction Of Cyanamide-peroxide With Creosolmentioning

confidence: 99%

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Reactions of Lignin with Cyanamide Activated Hydrogen Peroxide. Part 2. The Degradation Mechanism of Phenolic Lignin Model Compounds

Kadla¹,

Chang²,

Chen³

et al. 1998

Holzforschung

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“…Modellphenole, spezifisch markiert an allen C-Atomen gaben als Abbauprodukte CO, CO 2 , Ameisensäure, Essigsäure, Oxalsäure, Aceton, Methanol und die entsprechenden aromatischen Carbonsäuren und Aldehyde (Kratzl, Claus, Vierhapper 1972).…”

Section: Discussionunclassified

Modellversuche zur Sauerstoffbleiche von Zellstoff. 2. Mitt. Oxidation von Glucose-I-¹⁴C; Isolierung flüchtiger Bruchstücke

Kratzl¹,

Schwarz²

1975

Holzforschung

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“…Quinoide compounds seem to be important key intermediates in the natural formation of humic substances. They can be formed via both, homolytic (Kratzl et al 1967) and heterolytic processes (Gierer et al 1977) from any (substituted: guaiacyl, syringyl type) phenylpropane unit that bears a free phenolic group. Although these studies were based on lignin, lignite still contains phenylpropane units bearing free phenolic OH groups as lignin does (Wender 1976).…”

Section: Phenanthrene Sorptionmentioning

confidence: 99%

Effect of ammonoxidation on lignite properties

et al. 2009

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Oxidised lignite is a potential alternative source of N fertilizers. Ammonoxidation is the reaction of a given substrate with oxygen in aqueous ammonia. Lignite ammonoxidation is used for converting low-rank lignite into slowly nitrogen-releasing artificial humic matter. A lignite sample is compared before and after ammonoxidation in terms of geochemical and petrological properties, as well as the acid-base and physical hydrophobic sorptive behavior. The most obvious change caused by ammonoxidation is the decrease of attrinite, texto-ulminite and textinite in favor mainly of densinite and gelohuminite. In general, the ammonoxidative reactions promote the destruction of the structured humic macerals (texto-ulminite, textinite), and the formation of gels, which resulted in the cementation of the freely fine humic particles (attrinite). The pzc values are 3.4 and 4.3 for oxidised and nonoxidised lignite, respectively. After ammonoxidation the contents of carboxylic and free phenolic groups are found to be lower. The oxidised lignite shows a statistically lower sorptive capacity and affinity than the original sample due to a possible decrease in the hydrophobicity of the lignite.

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Zur Oxydation von14C-markierten Phenolen (Ligninmodellen) in wäßrig-alkalischer Lösung mit Sauerstoff

Cited by 31 publications

References 0 publications

Reactions of Lignin with Cyanamide Activated Hydrogen Peroxide. Part 2. The Degradation Mechanism of Phenolic Lignin Model Compounds

Reactions of Lignin with Cyanamide Activated Hydrogen Peroxide. Part 2. The Degradation Mechanism of Phenolic Lignin Model Compounds

Modellversuche zur Sauerstoffbleiche von Zellstoff. 2. Mitt. Oxidation von Glucose-I-¹⁴C; Isolierung flüchtiger Bruchstücke

Effect of ammonoxidation on lignite properties

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Zur Oxydation von14C-markierten Phenolen (Ligninmodellen) in wäßrig-alkalischer Lösung mit Sauerstoff

Cited by 31 publications

References 0 publications

Reactions of Lignin with Cyanamide Activated Hydrogen Peroxide. Part 2. The Degradation Mechanism of Phenolic Lignin Model Compounds

Reactions of Lignin with Cyanamide Activated Hydrogen Peroxide. Part 2. The Degradation Mechanism of Phenolic Lignin Model Compounds

Modellversuche zur Sauerstoffbleiche von Zellstoff. 2. Mitt. Oxidation von Glucose-I-14C; Isolierung flüchtiger Bruchstücke

Effect of ammonoxidation on lignite properties

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Product

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Modellversuche zur Sauerstoffbleiche von Zellstoff. 2. Mitt. Oxidation von Glucose-I-¹⁴C; Isolierung flüchtiger Bruchstücke