On the Acidolytic Cleavage of Arylglycerol beta-Aryl Ethers.

Karlsson, Olov; Lundquist, Knut; Meuller, S.; Westlid, Katarina; Lönnberg, Harri; Berg, Jan-Eric; Bartók, Mihály; Pelczer, István; Dombi, György

doi:10.3891/acta.chem.scand.42b-0048

Cited by 40 publications

(26 citation statements)

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“…The most important reaction during acidolysis of lignin is the cleavage of the β-O-4 bonds. This cleavage reaction has been described by several authors (Adler et al 1957;Lundquist and Lundgren 1972;Lundquist 1973;Ito et al 1981;Yasuda et al 1981aYasuda et al , b, 1982Yasuda et al , 1985Hoo et al 1983;Karlsson et al 1988). The mechanism for this cleavage reaction (as reported by Lundquist and Lundgren) is shown in Fig.…”

Section: Lignin Reactions Under Acidic Conditions β-O-4 Bond Cleavagementioning

confidence: 73%

“…In fact, the α-ether linkage has been reported to have a higher rate of reaction under mildly acidic conditions than the β-ether linkage and will be reviewed later. Speculation about the impact of different acids and the ability of their conjugate bases to abstract a β-proton from II has been discussed in the literature (Ito et al 1981;Yasuda et al 1985;Karlsson et al 1988). It has been reported that the rate of β-O-4 cleavage is dependent upon the type of conjugate base employed and that the rate of cleavage reactions follows the order HBr > HCl > H 2 SO 4 .…”

Section: Impact Of Acid Type On β-O-4 Cleavage Reaction Pathwaysmentioning

confidence: 99%

See 1 more Smart Citation

Wood Based Lignin Reactions Important to the Biorefinery and Pulp and Paper Industries

Santos¹,

Hart²,

Jameel³

et al. 2013

BioResources

128

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Section: Lignin Reactions Under Acidic Conditions β-O-4 Bond Cleavagementioning

confidence: 73%

Section: Impact Of Acid Type On β-O-4 Cleavage Reaction Pathwaysmentioning

confidence: 99%

Wood Based Lignin Reactions Important to the Biorefinery and Pulp and Paper Industries

Santos¹,

Hart²,

Jameel³

et al. 2013

BioResources

128

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“…In the first phase of the acidolysis, benzylic carbocation is formed (Li et al 2000;Lai 2001). The degradation can then progress to produce the so-called "Hibbert ketones", or homovanillin derivatives, via cleavage of the γ carbon (Adler et al 1957;Lundquist and Lundgren 1972;Karlsson et al 1988;Karlsson and Lundquist 1992). These reactions are, however, competed by nucleophilic addition reactions to the carbocation, typically resulting in the formation of β-aryl-type condensation products (Li et al 2007).…”

Section: Introductionmentioning

confidence: 99%

Characterization of dissolved lignins from acetic acid Lignofibre (LGF) organosolv pulping and discussion of its delignification mechanisms

et al. 2014

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Birch chips were cooked by means of the Lignofibre (LGF) organosolv process in acetic acid (AA) and phosphinic acid (H 3 PO 2 ) at 150°C. The delignification rate and structure of the dissolved lignin was followed as a function of time. The degree of delignification increased steadily up to 88% during the 120 min treatment time. The dissolved lignins were precipitated from the spent liquor (SL) by water addition, washed, and purified for the analyses. Elemental analysis, 31 P nuclear magnetic resonance (NMR), heteronuclear single-quantum coherence (HSQC) NMR, pyrolysis-gas chromatography/mass spectrometry (GC/MS), and gel permeation chromatography (GPC) were applied for the structural elucidation. It was found that the cleavage of the β-aryl ether linkages is the main reaction leading to delignification, accompanied by the formation of free phenolic hydroxyl groups and reduction in the content of aliphatic hydroxyl groups. The structure of the dissolved lignin remained the same after the drastic changes at the early stages of cooking (up to 30 min cooking time), indicating that secondary reactions (e.g., condensation) do not take place to a significant extent. H 3 PO 2 probably enhances the acidolysis reaction via an ester derivative that both boosts the cleavage reaction and prevents the formation of the carbocation intermediate that induces condensation. Homolytic cleavage reactions may take place parallel to the acidolytic reactions.

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“…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. It was well documented that β-O-4 aryl ether models were degraded into guaiacol and Hibbert's ketones via enol ethers intermediates formed from acid catalyzed dehydration of the 1,3-diol model; meanwhile the released guaiacol attacked the benzyl cation resulting in the condensation product (supporting information, Figure S1).…”

Section: Introductionmentioning

confidence: 99%

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

Zhao

Yue

et al. 2020

Polymers

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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.

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On the Acidolytic Cleavage of Arylglycerol beta-Aryl Ethers.

Cited by 40 publications

References 0 publications

Wood Based Lignin Reactions Important to the Biorefinery and Pulp and Paper Industries

Wood Based Lignin Reactions Important to the Biorefinery and Pulp and Paper Industries

Characterization of dissolved lignins from acetic acid Lignofibre (LGF) organosolv pulping and discussion of its delignification mechanisms

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

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