Acid Degradation of Lignin. VI. Formation of Methanol.

Lundquist, Knut; Ericsson, Lennart

doi:10.3891/acta.chem.scand.25-0756

Cited by 21 publications

(9 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Acidolysis of lignin has received considerable attention due to the relevance of this method to the biorefinery concept. This approach was originally used to aid structural elucidation , and more recently for the production of well-defined aromatic compounds. , Using model compounds, two different reaction pathways (C2 and C3 pathways, Scheme ) have been identified for the cleavage of the β-O-4 linkage and modification of the β-5 linkage. ,, While the C3 pathway provides the Hibbert ketones, the C2 pathway yields C2-aldehydes upon release of formaldehyde, which can then undergo condensation reactions. ,, The balance of these pathways depends on the nature of the mineral acid used. With HBr, the C3 pathway dominates, whereas H 2 SO 4 favors the C2 pathway. , Similar observations were made regarding the reactivity of the β-5 linkage.…”

Section: Resultsmentioning

confidence: 99%

Advanced Model Compounds for Understanding Acid-Catalyzed Lignin Depolymerization: Identification of Renewable Aromatics and a Lignin-Derived Solvent

et al. 2016

View full text Add to dashboard Cite

ABSTRACT:The development of fundamentally new approaches for lignin depolymerization is challenged by the complexity of this aromatic biopolymer. While overly simplified model compounds often lack relevance to the chemistry of lignin, the use of lignin streams directly, poses significant analytical challenges to methodology development. Ideally, new methods should be tested on model compounds that are complex enough to mirror the structural diversity in lignin, but still of sufficiently low molecular weight to enable facile analysis. In this contribution we present a new class of advanced (β-O-4)-(β-5) dilinkage models that are highly realistic representations of a lignin fragment. Together with selected β-O-4, β-5 and β-β structures, these compounds provide a detailed understanding of the reactivity of various types of lignin linkages in acid catalysis in conjunction with stabilization of reactive intermediates using ethylene glycol. The use of these new models has allowed for identification of novel reaction pathways and intermediates and led to the characterization of new dimeric products in subsequent lignin depolymerization studies. The excellent correlation between model and lignin experiments highlights the relevance of this new class of model compounds for broader use in catalysis studies. Only by understanding the reactivity of the linkages in lignin at this level of detail can fully optimized lignin depolymerization strategies be developed.

show abstract

Section: Resultsmentioning

confidence: 99%

Advanced Model Compounds for Understanding Acid-Catalyzed Lignin Depolymerization: Identification of Renewable Aromatics and a Lignin-Derived Solvent

et al. 2016

View full text Add to dashboard Cite

show abstract

“…Initially formed dimers of vanillyl glycol lack free ortho and para positions, and enzymic oxidation can therefore be expected to result in the formation of products of the cyclohexadienone type (for examples, see Lundquist & Ericsson, 1971). The susceptibilities of methoxy groups in such compounds to acid-catalysed hydrolysis has been studied (Lundquist & Ericsson, 1971;Hemra & Lundquist, 1973). Such an acidcatalysed mechanism provides an explanation for the pH-dependence of the demethylation reaction (Ishihara, 1983).…”

mentioning

confidence: 99%

Exhaustive laccase-catalysed oxidation of a lignin model compound (vanillyl glycol) produces methanol and polymeric quinoid products

Lundquist¹,

Kristersson²

1985

Biochemical Journal

View full text Add to dashboard Cite

Laccase-catalysed oxidation of the lignin-related phenol vanillyl glycol results in the initial formation of dimers and subsequent polymerization. The polymerization is accompanied by a liberation of methanol corresponding to 15-20% demethylation. Visible spectra together with reduction experiments suggest the simultaneous formation of o-quinones. The participation of quinone formation in the polymerization process and the possible role of such intermediates in lignin biodegradation is discussed.

show abstract

“…From the results shown in Figure 2, it was suggested that 1,3-dioxane structures 1 were produced in 2 min and their yields reached the maximum in 5 min following a quick decline, and then almost disappeared in 40 min. It should be mentioned that no such 1,3-dioxane products were ever reported from GG under conventional acidolysis conditions [11][12][13][14][15][16][17][18]29]. To better understand the fate of 1,3-dioxane intermediate compound 1, the synthesized 1 was subjected to the acidic treatment in an aqueous GVL solvent.…”

Section: Reactions Of β-O-4 Lignin Model Gg In Gvl/ H 2 O (80/20) Systemmentioning

confidence: 99%

“…During the period of 1967-1972, Lundquist et al [11][12][13] investigated the reaction mechanisms of β-O-4 lignin model compounds and Björkman lignin from spruce under acidolysis conditions (90% 1,4-dioxane, and 0.2 mol/l HCl under reflux). Yasuda et al [14][15][16][17] also proposed acidolysis mechanisms of β-O-4 lignin models.…”

Section: Introductionmentioning

confidence: 99%

Revealing Structural Modifications of Lignin in Acidic γ-Valerolactone-H2O Pretreatment

Zhao

Yue

et al. 2020

Polymers

View full text Add to dashboard Cite

γ-valerolactone (GVL)/H2O/acid solvent mixtures has been used in chemical pretreatment of lignocellulosic biomass, it was claimed that GVL lignins were structurally close to proto (native) lignins, or having low molecular weight with narrow polydispersity, however, the structural changes of GVL lignins have not been investigated. In this study, β-O-4 (β-aryl ether, GG), β-5 (phenylcoumaran), and β-β (resinol) lignin model compounds were treated by an acidic GVL-H2O solvent system, a promising pretreatment of lignocellulose for biomass utilization, to investigate the structural changes possibly related to the lignin involved. NMR characterization of the products isolated from the treated GG indicated that a phenyl dihydrobenzofuran, having typical C-H correlations at δC/δH 50.74/4.50 and 93.49/4.60 ppm in its HSQC spectrum, was produced from GG. In the pretreatment, the released formaldehyde from GG reacted fast with GG to form a novel 1,3-dioxane intermediate whose characteristic HSQC signals were: δC/δH 94.15–94.48/4.81–5.18 ppm and 80.82–83.34/4.50–4.94 ppm. The β-5 model, dihydrodehydrodiconiferyl alcohol, was converted into phenylcoumarone and stilbene having benzaldehyde that resulted from the allyl alcohol side chain. The β-β model, syringaresinol, was isomerized to form a mixture of syringaresinol, epi-, and dia-syringaresinol although being degraded slightly.

show abstract

Acid Degradation of Lignin. VI. Formation of Methanol.

Cited by 21 publications

References 0 publications

Advanced Model Compounds for Understanding Acid-Catalyzed Lignin Depolymerization: Identification of Renewable Aromatics and a Lignin-Derived Solvent

Advanced Model Compounds for Understanding Acid-Catalyzed Lignin Depolymerization: Identification of Renewable Aromatics and a Lignin-Derived Solvent

Exhaustive laccase-catalysed oxidation of a lignin model compound (vanillyl glycol) produces methanol and polymeric quinoid products

Revealing Structural Modifications of Lignin in Acidic γ-Valerolactone-H2O Pretreatment

Contact Info

Product

Resources

About