Comprehensive Study on the Chemical Structure of Dioxane Lignin from Plantation <i>Eucalyptus globulus</i> Wood

Evtuguin, Dmitry V.; Neto, Carlos Pascoal; Silva, Artur M. S.; Domingues, Pedro; Amado, Francisco; Robert, D.; Faix, O.

doi:10.1021/jf010315d

Cited by 215 publications

(235 citation statements)

References 30 publications

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“…However, when considering the data of Table 2, the absence of degradation products derived from H units in the thioacidolysis products from E. globules is noteworthy. This absence is in complete agreement with the work of Evtuguin et al, 11 and it has been rationalized on the basis of the low yields of H-type lignin structures in the thioacidolysis. 11,27 Furthermore, both techniques also showed remarkable similarities for determining the total number of guaiacyl units involved in uncondensed -aryl bonds in lignins isolated from normal and compressed woods (Table 2).…”

Section: Resultssupporting

confidence: 90%

“…This absence is in complete agreement with the work of Evtuguin et al, 11 and it has been rationalized on the basis of the low yields of H-type lignin structures in the thioacidolysis. 11,27 Furthermore, both techniques also showed remarkable similarities for determining the total number of guaiacyl units involved in uncondensed -aryl bonds in lignins isolated from normal and compressed woods (Table 2). However, in the particular case of lignin from compression wood, a significant difference was observed in the amount of uncondensed H units determined by thioacidolysis and DFRC/ 31 P NMR: 204 versus 74 µmol/g, respectively.…”

Section: Resultssupporting

confidence: 90%

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Determination of Arylglycerol−β-Aryl Ether Linkages in Enzymatic Mild Acidolysis Lignins (EMAL): Comparison of DFRC/³¹P NMR with Thioacidolysis

et al. 2008

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Enzymatic mild acidolysis lignins (EMAL) isolated from different species of softwood and Eucalyptus globulus were submitted to comparative analysis that included thioacidolysis, derivatization followed by reductive cleavage (DFRC), and DFRC followed by quantitative 31 P NMR (DFRC/ 31 P NMR). While gas chromatography (GC) was used to determine the monomer yields from both thioacidolysis and DFRC, 31 P NMR studies quantified the various phenolic hydroxy groups released by DFRC. The monomer yields from thioacidolysis and DFRC were substantially different, with thioacidolysis resulting in higher yields. In contrast, an excellent agreement was obtained in the total number of -aryl ether structures determined by thioacidolysis and DFRC/ 31 P NMR, indicating that the combination of DFRC with quantitative 31 P NMR overcomes, at least in part, the limitations presented by the DFRC method. Both thioacidolysis and DFRC/ 31 P NMR were further used to better understand the lignin isolation process from wood. The results show that mild rotary ball milling minimizes, but does not prevent, the degradation of -O-4 structures during the early stages of wood pulverization. The extent of such degradation was found to be higher for E. globulus than for a variety of softwoods examined. Furthermore, the structures of the EMALs isolated at yields ranging from 20% to 62% were very similar, indicating structural homogeneity in the lignin biopolymer within the secondary wall.Lignin is a complex and irregular natural polymer built up of different interunit linkages. 1 While the bulk of lignin in wood consists of nonphenolic -aryl ether units, other units, such as phenylcoumaran ( -5), resinol ( -), and dibenzodioxocins (5-5/ -O-4, R-O-4), are also present in lower amounts within the lignin macromolecule. 1,2 According to the current understanding, almost all lignin macromolecules in softwood and softwood pulps are covalently linked to polysaccharides, mainly hemicelluloses. 3,4 A primary problem in elucidating lignin structure has been the isolation of total lignin from wood in a chemically unaltered form. 5-9 Overall, two approaches have been used to isolate lignin from lignocellulosics: acidolysis methods 10,11 and extraction of lignin after ball milling. 5,6,12 Despite resulting in lignin preparations with high yields and purities, severe acid concentrations (usually 0.2 M) trigger some changes in lignin structure. 10,11 On the other hand, traditional ball-milling-based methods, such as the milled wood lignin (MWL) and cellulolytic enzyme lignin (CEL) protocols, offer less modified lignin than those obtained by severe acid treatments. However, the yields of such lignins are dependent on milling intensity. [7][8][9]13 Intensive milling protocols offered by vibratory-and orbital-milling devices provide higher lignin yields within relatively short milling intervals, although at the expense of the integrity of the lignin macromolecule and associated condensation and oxidation reactions. 8,9,13,14 Low-intensity milling minimizes structural c...

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Section: Resultssupporting

confidence: 90%

Section: Resultssupporting

confidence: 90%

Determination of Arylglycerol−β-Aryl Ether Linkages in Enzymatic Mild Acidolysis Lignins (EMAL): Comparison of DFRC/³¹P NMR with Thioacidolysis

et al. 2008

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“…It is known that 1,4-dioxane can dissolve lignin, and extract lignin from lignocellulose. 56 Our study shows that birch lignin is converted into propenylsubstituted phenols (propenylguaiacol 28% and propenylsyringol 67%) as dominant products instead of propylsubstituted compounds (Table 1, entry 8). The property of 1,4-dioxane is greatly different from alcohols.…”

Section: Resultsmentioning

confidence: 76%

Lignin depolymerization (LDP) in alcohol over nickel-based catalysts via a fragmentation–hydrogenolysis process

Song

Wang

Cai

et al. 2013

Energy Environ. Sci.

789

650

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Valorization of native birch wood lignin into monomeric phenols over nickel-based catalysts has been studied. High chemoselectivity to aromatic products was achieved by using Ni-based catalysts and common alcohols as solvents. The results show that lignin can be selectively cleaved into propylguaiacol and propylsyringol with total selectivity >90% at a lignin conversion of about 50%. Alcohols, such as methanol, ethanol and ethylene glycol, are suitable solvents for lignin conversion. Analyses with MALDI-TOF and NMR show that birch lignin is first fragmented into smaller lignin species consisting of several benzene rings with a molecular weight of m/z ca. 1100 to ca. 1600 via alcoholysis reaction. The second step involves the hydrogenolysis of the fragments into phenols. The presence of gaseous H 2 has no effect on lignin conversion, indicating that alcohols provide active hydrogen species, which is further confirmed by isotopic tracing experiments. Catalysts are recycled by magnetic separation and can be reused four times without losing activity. The mechanistic insights from this work could be helpful in understanding native lignin conversion and the formation of monomeric phenolics via reductive depolymerization. Broader contextNature efficiently synthesizes aromatic structures and deposits them as lignin in plants. Incorporation of catalytic technologies into lignin conversion is a possible option for valorizing the feedstock as a renewable raw material for aromatic chemical production. Use of heterogeneous catalysts facilitates separation and recycling, and has attracted great attention. However, the detailed chemistry between solid catalysts and solid feedstocks still remains unknown because of mass transfer limitations. Herein we report the valorization of native birch wood lignin into monomeric phenols over nickel-based catalysts. High chemoselectivity to aromatic products was achieved by using Ni-based catalysts and common alcohols as solvents. The results show that lignin can be selectively cleaved into propylguaiacol and propylsyringol with total selectivity >90% at a lignin conversion of about 50%. Analysis results show that birch lignin is rst fragmented into smaller lignin species consisting of several benzene rings with a molecular weight of m/z ca. 1100 to ca. 1600 via alcoholysis reaction. The second step involves the hydrogenolysis of the fragments into phenols. This study will greatly contribute to the understanding of the lignin depolymerization reaction and will be interesting for other biomass conversion.

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“…The acid hydrolysis method for lignin isolation is detailed elsewhere (Evtuguin et al, 2001). A subsample of the BLF fraction was refluxed in 0.1 M HCl solution containing 82:18 dioxane/water for 2 h under N 2 , and the mixture then separated by centrifugation.…”

Section: Sorbent Isolationmentioning

confidence: 99%

“…In the paper industry, some chemical treatments have been widely applied to isolate lignin from pulp (Gellerstedt et al, 1994). It has been reported that isolation with dioxane was considered as a relatively ''soft'' method because of less alteration to the extracted lignin (Gellerstedt et al, 1994;Evtuguin et al, 2001). Therefore, a dioxane-acid hydrolysis method was applied to the lignin isolation in this study.…”

Section: Introductionmentioning

confidence: 99%

Role of extractable and residual organic matter fractions on sorption of phenanthrene in sediments

2013

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h i g h l i g h t s" Riverine sediments were fractionated into five fractions using new methods. " A dioxane extraction procedure was applied to the separation of lignin in sediments. " Free lipid and lignin were much higher than previously reported values. " The Phen sorption for the lipid and lignin fractions was linear, whereas that for the residual fractions was nonlinear. . The sorption isotherms of phenanthrene (Phen) were examined to evaluate the importance of various fractions on sorption. A lignin extraction procedure was for the first time applied to separate the lignin or degraded lignin fraction from sediment organic matter (SOM). The extracted LG was similar to model lignin in terms of elemental ratios and sorption behavior. FL and LG fractions were quite important, as their contents were much higher than reported values. Phen sorption for the extracted fractions was almost linear, whereas that for the residual fractions was nonlinear, especially for LGF with n 0.56-0.63. As the different organic fractions were removed sequentially, sorption energy distribution on the residual sediment organic matter (SOM) became more heterogeneous. In addition, increasing sorption capacity for the residual fractions, except for BLF with its high polarity, suggested that more sorption sites on the SOM matrix became accessible to Phen. The sorption capacity for LGF was comparable to that of condensed SOM. The residual fraction LGF generally controlled the overall sorption at low Phen concentration, but the extractable fraction FL surpassed the former fraction at high Phen concentration, demonstrating the importance of condensed SOM in the sorption of hydrophobic organic compounds (HOCs) in sediments.

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Comprehensive Study on the Chemical Structure of Dioxane Lignin from Plantation Eucalyptus globulus Wood

Cited by 215 publications

References 30 publications

Determination of Arylglycerol−β-Aryl Ether Linkages in Enzymatic Mild Acidolysis Lignins (EMAL): Comparison of DFRC/³¹P NMR with Thioacidolysis

Determination of Arylglycerol−β-Aryl Ether Linkages in Enzymatic Mild Acidolysis Lignins (EMAL): Comparison of DFRC/³¹P NMR with Thioacidolysis

Lignin depolymerization (LDP) in alcohol over nickel-based catalysts via a fragmentation–hydrogenolysis process

Role of extractable and residual organic matter fractions on sorption of phenanthrene in sediments

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Comprehensive Study on the Chemical Structure of Dioxane Lignin from Plantation Eucalyptus globulus Wood

Cited by 215 publications

References 30 publications

Determination of Arylglycerol−β-Aryl Ether Linkages in Enzymatic Mild Acidolysis Lignins (EMAL): Comparison of DFRC/31P NMR with Thioacidolysis

Determination of Arylglycerol−β-Aryl Ether Linkages in Enzymatic Mild Acidolysis Lignins (EMAL): Comparison of DFRC/31P NMR with Thioacidolysis

Lignin depolymerization (LDP) in alcohol over nickel-based catalysts via a fragmentation–hydrogenolysis process

Role of extractable and residual organic matter fractions on sorption of phenanthrene in sediments

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Determination of Arylglycerol−β-Aryl Ether Linkages in Enzymatic Mild Acidolysis Lignins (EMAL): Comparison of DFRC/³¹P NMR with Thioacidolysis

Determination of Arylglycerol−β-Aryl Ether Linkages in Enzymatic Mild Acidolysis Lignins (EMAL): Comparison of DFRC/³¹P NMR with Thioacidolysis