The reactions of alkaline hydrogen peroxide with lignin model dimers

Omori, Shigetoshi; Dence, C. W.

doi:10.1007/bf00367858

Cited by 36 publications

(23 citation statements)

References 13 publications

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“…This is evidenced by the fact that 0.03 mmol of the peroxide was consumed in oxidizing only 0.02 mmol of the dimer while the combined yield of identified products accounted for only 9-10% of the dimer consumed. The same phenomenon was observed previously (Bailey, Dence 1965;Kempf, Dence 1975;Omori, Dence 1981a;Omori, Dence 1981b) when monomeric and dimeric lignin model compounds were reacted with alkaline peroxide. Based on the types of products identified, it appears that the main reactions of -l diols with stabilized alkaline peroxide (i.e., under mainly O 2 -free conditi ns) involve the nucleophilic attack of HO 2~ on the quinonemethide III, and oxidation of the stilbene, IV.…”

Section: Resultssupporting

confidence: 78%

“…Other compounds used in the study were synthesized following procedures described in the literature: -hydroxyacetoguaiacone X, methoxyhydroquinone, and methoxybenzoquinone (Omori, Dence 1981a), guaiacylglycol VIII, , and vanillic acid (Pearl 1956). The following compounds were purchased from Aldrich Cemicals and used äs a reference or starting materials without further purification: vanillin, ethylvanillin, guaiacylglycol, 1,2,4-trihydroxybenzene, succinic acid, oxalic acid, hydroxymaleic acid, malonic acid, and ^iycolic acid.…”

Section: Preparation Of Model Compoundsmentioning

confidence: 99%

“…In previous studies in this series, the reactions of alkaline hydrogen peroxide with phenacyl -aryl ethers (Omori, Dence 1981 a) and guaiacylglycerol-ß-guaiacyl ether (Omori, Dence 1981b) were examined under conditions approximating those used in the technical bleaching of mechanical pulps. The degradation of these two types of lignin dimers proceeded mainly via the Dakin and Dakin-like reactions, respectively, and was found to be influenced by factors affecting peroxide stability, e.g., pH and the presence or absence of stabilizers.…”

Section: Introductionmentioning

confidence: 99%

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The Reactions of Alkaline Hydrogen Peroxide with Lignin Model Dimers Part 3: 1,2-Diaryl-1,3-Propanediols

Nonni¹,

Dence²

1988

Holzforschung

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Two l,2-diaryl-l,3,-propanediols,l-(3-ethoxy-4-hydroxyphenyl)-2-(4-hydroxy-3-methoxyphenyl)-l,3-propanediol and l,2-bis(4-hydroxy-3-methoxyphenyl)-l,3-propanediol, were reacted with stabilized (Na 5 DTPA) ä*nd non-stabilized hydrogen peroxide under simulated bleaching conditions. Several products were identified and their yields estimated using a combination of GC and GC/MS techniques. The effect of dilute aqueous alkali (pH 10.5) was to partiaJJy convert the diols to stilbene derivatives. In the presence of alkaline hydrogen peroxide (especially non-stabilized) and oxygen, the main products identified includcd vanillin, 3-ethoxy-4-hydroxybenzaldehyde (hereinafter referred to äs ethylvanillin), DL-4-hydroxy-3-methoxyphenylgIycol (hereinafter referred to äs guaiacylglycol), co-hydroxyacetoguaiacone, ethanol and methanol. The formation of these products was rationalized on the basis of mechanisms involving a combination of nucleophilic attack by hydroperoxide anion on intermediate quinonemethides and a-(4-hydroxy-3-methoxyphenyl)-ß-hydroxypropionaldehyde, and electrophilic attack of oxygen, added or formed by peroxide decomposition, on the phenolate rings and intermediate stilbenes.

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Section: Resultssupporting

confidence: 78%

Section: Preparation Of Model Compoundsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Reactions of Alkaline Hydrogen Peroxide with Lignin Model Dimers Part 3: 1,2-Diaryl-1,3-Propanediols

Nonni¹,

Dence²

1988

Holzforschung

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“…Thus, it is obvious that the ligninretaining hydrogen peroxide bleaching can be achieved only under carefully controlled conditions. In the past several decades, studies on the reactions of hydrogen peroxide with lignin model compounds (Reeves and Pearl 1965;Bailey and Dence 1969;Kempf and Dence 1975;Gierer and Imsgard 1977;Agnemo and Gellerstedt 1979;Hosoya et al 1979, Hosoya andNakano 1980;Gellerstedt and Agnemo 1980 a;Omori and Dence 1981;Nonni and Dence 1988) have been undertaken primarily äs a means of understanding the manner in which hydrogen peroxide functions äs a pulp brightening agent. It has been shown (Bailey and Dence 1969;Kempf and Dence 1975) that the phenolic units of the models are extensively degraded, yielding ultimately a variety of aliphatic acid fragments.…”

Section: Introductionmentioning

confidence: 99%

On the Behaviour of Spruce Thermomechanical Pulp Lignin during Hydrogen Peroxide Bleaching

Pan¹,

Lachenal²,

Lapierre³

et al. 1994

HFSG

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Lignins were isolated from spruce TMP and hydrogen peroxide bleached TMP (BTMP) by means of enzymatic hydrolysis with cellulases in yields of 67 and 78%, respectively. In addition, the TMP lignin, TMP EL, was subjected to a treatment with bleaching agent to obtain a bleached lignin, TMP ELB. The three lignin samples were all characterized by thioacidolysis and 13 C-NMR spectroscopy. Comparison of these lignin samples provided evidence about the behaviour of lignin towards alkaline hydrogen peroxide bleaching. It has been demonstrated that the bleaching does not affect the overall structure of lignin. The only one major change of the lignin moiety is elimination of coniferaldehyde end structures, which would be an important contribution to the brightening of pulp.

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“…The barium salt of vanillyl alcohol sulfonate (XVII) (4-hydroxy-3-methoxytoluene-tü-sulfonic acid barium salt had been prepared previously using the method of Lindgren (1979). The procedure for the preparation of -methylvanillyl alcohol (VII) has been described previously (Omori and Dence 1981). Isoeugenol (III), benzophenone and acetophenone were obtained from Aldrich Chemical Company.…”

Section: Chemicalsmentioning

confidence: 99%

Studies on the Mechanism of the Photoyellowing of Bleached Mechanical and Chemimechanical Pulps II. The Role of Photosensitizers

Omori¹,

Francis²,

Dence³

1991

Holzforschung

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Photoscnsitizing and non-photoscnsitizing lignin modcl compounds wcrc depositcd individuully and in combinations on filtcr papcr and cxposcd to light from a 1000 W mcrcury-tungstcn sourcc for varying pcriods of timc. Any photoyellowing was mcasurcd s a changc in Elrcpho brightncss at 457 nm. In a fcw instanccs, the irradiatcd matcrial was cxtractcd from the papcr and analyzcd by capillary column GC and by GC/MS. The photoyellowing of α-mcthylvanillyl alcohol (apocynol) was found to bc grcatly cnhanccd whcn irradiated in combination with a photoscnsitizer such s acctovcratronc.This finding supports the vicw that the initial stcp in the photoyellowing proccss involvcs the abstraction of a phcnolic hydroxyl hydrogcn by a photoscnsitizer group. α-Mcthylvanillyl and α-mcthylvcratryl alcohols wcrc photoconvcrtcd in Iow yicld to the corrcsponding α-carbonyl compounds, acctoguaiaconc and acctovcratronc. and todimcricstructurcs.Thc photoyellowing of non-scnsitizer phcnolic modcl compounds was shown to depcnd to a small dcgrcc on the substitucnt at the a-position.

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The reactions of alkaline hydrogen peroxide with lignin model dimers

Cited by 36 publications

References 13 publications

The Reactions of Alkaline Hydrogen Peroxide with Lignin Model Dimers Part 3: 1,2-Diaryl-1,3-Propanediols

The Reactions of Alkaline Hydrogen Peroxide with Lignin Model Dimers Part 3: 1,2-Diaryl-1,3-Propanediols

On the Behaviour of Spruce Thermomechanical Pulp Lignin during Hydrogen Peroxide Bleaching

Studies on the Mechanism of the Photoyellowing of Bleached Mechanical and Chemimechanical Pulps II. The Role of Photosensitizers

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