Comparative studies on oxidation of lignin model compounds with hydrogen peroxide using Mn(IV)-Me3TACN and Mn(IV)-Me4DTNE as catalyst

2003 ◽  
Vol 206 (1-2) ◽  
pp. 37-51 ◽  
Author(s):  
Vera Alves ◽  
Ewellyn Capanema ◽  
Chen-Loung Chen ◽  
Josef Gratzl
Keyword(s):  
Hydrogen Peroxide ◽  
Comparative Studies ◽  
Model Compounds ◽  
Lignin Model Compounds ◽  
Lignin Model

The Reactions of Lignin Model Compounds with Hydrogen Peroxide at Low pH

Holzforschung ◽  
2003 ◽  
Vol 57 (1) ◽  
pp. 52-88 ◽  
Author(s):  
T. Kishimoto ◽  
J. F. Kadla ◽  
H.-m. Chang ◽  
H. Jameel
Keyword(s):  
Hydrogen Peroxide ◽  
Reaction System ◽  
Model Compounds ◽  
Reaction Conditions ◽  
Lignin Model Compounds ◽  
Lignin Model Compound ◽  
Lignin Model ◽  
Decreasing Ph ◽  
Hydroxyl Compounds ◽  
Acidic Hydrogen

Summary In peroxymonosulfuric acid bleaching, the presence of hydrogen peroxide is dependent on the reaction conditions and the conversion ratios used to generate the peroxy acid. Substantial amounts of hydrogen peroxide may be present in the reaction system under certain conditions. An understanding of the reactions of hydrogen peroxide under these conditions would be beneficial. Therefore, several simple lignin model compounds were reacted with acidic hydrogen peroxide, pH 1-3, at 70°C. In all cases the phenolic lignin model compounds reacted much faster than their non-phenolic counterparts. In fact, the extent of reaction was very much dependent on the structure of the lignin model compound. The α-hydroxyl compounds, 4-(1-Hydroxy-ethyl)-2-methoxy-phenol and 1-(3,4-Dimethoxy-phenyl)-ethanol, reacted faster than the corresponding α-carbonyl compounds with both reacting much faster than the aromatic compounds, with simple alkyl substituents. A new reaction mechanism for α-hydroxyl compounds is proposed, in which benzyl carbocation formation is followed by nucleophilic addition of hydrogen peroxide. Unlike the mechanisms proposed in the past, no evidence of aromatic hydroxylation via perhydronium ion was observed. The reactivities were very pH dependent, in that higher reactivity was associated with lower pH. Decreasing pH further increased the amount of condensation products identified, such that condensation was competitive with degradation. These condensation reactions were also present under the Caro's acid bleaching conditions at pH below 2. However, under all conditions the reactivity of acidic peroxide was found to be much less than that of peroxymonosulfuric acid.

scholarly journals Regioselective Baeyer–Villiger oxidation of lignin model compounds with tin beta zeolite catalyst and hydrogen peroxide

RSC Advances ◽  
2017 ◽  
Vol 7 (42) ◽  
pp. 25987-25997 ◽  
Author(s):  
John A. Jennings ◽  
Sean Parkin ◽  
Eric Munson ◽  
Sean P. Delaney ◽  
Julie L. Calahan ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Zeolite Catalyst ◽  
Ester Hydrolysis ◽  
Beta Zeolite ◽  
Model Compounds ◽  
Lignin Model Compounds ◽  
System P ◽  
Benzylic Alcohol ◽  
Lignin Model ◽  
Villiger Oxidation

One approach to lignin deconstruction involves oxidation of benzylic alcohol groups, followed by Baeyer–Villiger oxidation (BVO) and ester hydrolysis. In this study β-O-4 and β-1 lignin models were oxidized using a heterogeneous BVO system.

Molecular basis of laccase bound to lignin: insight from comparative studies on the interaction of Trametes versicolor laccase with various lignin model compounds

RSC Advances ◽  
2015 ◽  
Vol 5 (65) ◽  
pp. 52307-52313 ◽  
Author(s):  
Ming Chen ◽  
Guangming Zeng ◽  
Cui Lai ◽  
Jian Li ◽  
Piao Xu ◽  
...  
Keyword(s):  
Comparative Studies ◽  
Molecular Basis ◽  
Trametes Versicolor ◽  
Model Compounds ◽  
Lignin Model Compounds ◽  
Lignin Model ◽  
Binding Orientation

Binding orientation of lignin model compounds in laccase.

Comparison Activating Ability of Three Hydrogen Peroxide Activators

2013 ◽  
Vol 641-642 ◽  
pp. 215-218
Author(s):  
Sheng Guo ◽  
De Yi Huang ◽  
Ji Feng She ◽  
Xiang Qun Liang
Keyword(s):  
Hydrogen Peroxide ◽  
Half Life ◽  
Model Compounds ◽  
Lignin Model Compounds ◽  
Bleaching Process ◽  
Peroxide Bleaching ◽  
Lignin Model ◽  
System 1 ◽  
Kinetics Of ◽  
H2o2 System

The bleaching efficiency of hydrogen peroxide can be promoted by using suitable activator. In our research, two methods were applied to compare the activating ability of three activators, TAED (tetraacetylethylenediamine), acetamide and dicyandiamide. The first part was hydrogen peroxide bleaching. TAED was excellent, because the brightness improvement was the maximum; the viscosity was acceptable. Acetamide was an applied activator in peroxide bleaching，for it could get same effects as TAED if the bleaching process had enough time and enough dosage. In the last part our study was about the kinetics of a lignin model compounds, acetovanillone, in peroxide-alone system, TAED/H2O2 system, acetamide/H2O2 system and dicyandiamide/H2O2 system. The rate constant, k and half-life period, t1/2 can be used to compare the rate of oxidation of acetovanilone. Compared to peroxide-alone system, three systems with activator and H2O2 could accelerate the reactions of hydrogen peroxide and acetovanillone. The t1/2 of TAED/H2O2 system was least of them. It was just 1/5 of t1/2 of peroxide-alone system, 1/4 of t1/2 of acetamide/H2O2 system and dicyandiamide/H2O2 system. The activating ability order of activators was: TAED> acetamide> dicyandiamide.

scholarly journals The effect of metal ions on the reaction of hydrogen peroxide with Kraft lignin model compounds

1999 ◽  
Vol 77 (5-6) ◽  
pp. 667-675 ◽  
Author(s):  
Yujun Sun ◽  
Michael Fenster ◽  
Annie Yu ◽  
Richard M Berry ◽  
Dimitris S Argyropoulos
Keyword(s):  
Hydrogen Peroxide ◽  
Transition Metals ◽  
Oxalic Acid ◽  
Alkaline Earth ◽  
Alkaline Earth Metals ◽  
Model Compounds ◽  
Lignin Model Compounds ◽  
Peroxide Bleaching ◽  
Radical Coupling ◽  
Lignin Model

Peroxide bleaching is significantly affected by transition and alkaline earth metals. Isolating the effects of different transition and alkaline earth metals on the reactions of peroxide with different representative lignin structures allows the separation of the positive from the negative contributions of these metal ions. In this work, five monomeric or dimeric phenolic lignin model compounds were treated with alkaline hydrogen peroxide in the absence or presence of Mn2+, Cu2+, Fe3+, and Mg2+. We followed the disappearance of the starting material and the progress of demethylation, radical coupling and oxalic acid formation were followed. Transition metals increased the reactivities of all the lignin model compounds with hydrogen peroxide in the order Mn2+ > Cu2+ > Fe3+, which is the same as the order of activity toward peroxide decomposition while Mg2+ stabilized the system. Demethylation, radical coupling, and oxalic acid formation were all increased by the presence of transition metals in the system and decreased by the addition of Mg2+. The acceleration of the total degree of reaction and of the demethoxylation reactions improves peroxide bleaching, but the increase in the radical coupling reactions can affect the further bleachability of pulp while the increase in the formation of oxalic acid could lead to a greater probability of scaling.Key words: lignins, hydrogen peroxide, peroxide bleaching, reactivity, chemical pulps, metal compounds, alkali treatment, transition metals, delignification.

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