- Controlling lignin solubility and hydrogenolysis selectivity by acetal-mediated functionalization
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Existing lignocellulosic biomass fractionation processes produce lignin with random, interunit C-C bonds that inhibit its depolymerization and constrain its use. Here, we exploit the aldehyde stabilization of lignin to tailor its structure, functionality,
- Dick, Graham R.,Komarova, Anastasia O.,Luterbacher, Jeremy S.
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supporting information
p. 1285 - 1293
(2022/02/17)
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- Efficient demethylation of aromatic methyl ethers with HCl in water
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A green, efficient and cheap demethylation reaction of aromatic methyl ethers with mineral acid (HCl or H2SO4) as a catalyst in high temperature pressurized water provided the corresponding aromatic alcohols (phenols, catechols, pyrogallols) in high yield. 4-Propylguaiacol was chosen as a model, given the various applications of the 4-propylcatechol reaction product. This demethylation reaction could be easily scaled and biorenewable 4-propylguaiacol from wood and clove oil could also be applied as a feedstock. Greenness of the developed methodversusstate-of-the-art demethylation reactions was assessed by performing a quantitative and qualitative Green Metrics analysis. Versatility of the method was shown on a variety of aromatic methyl ethers containing (biorenewable) substrates, yielding up to 99% of the corresponding aromatic alcohols, in most cases just requiring simple extraction as work-up.
- Bomon, Jeroen,Bal, Mathias,Achar, Tapas Kumar,Sergeyev, Sergey,Wu, Xian,Wambacq, Ben,Lemière, Filip,Sels, Bert F.,Maes, Bert U. W.
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p. 1995 - 2009
(2021/03/26)
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- Aromatic compound hydrogenation and hydrodeoxygenation method and application thereof
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The invention belongs to the technical field of medicines, and discloses an aromatic compound hydrogenation and hydrodeoxygenation method under mild conditions and application of the method in hydrogenation and hydrodeoxygenation reactions of the aromatic compounds and related mixtures. Specifically, the method comprises the following steps: contacting the aromatic compound or a mixture containing the aromatic compound with a catalyst and hydrogen with proper pressure in a solvent under a proper temperature condition, and reacting the hydrogen, the solvent and the aromatic compound under the action of the catalyst to obtain a corresponding hydrogenation product or/and a hydrodeoxygenation product without an oxygen-containing substituent group. The invention also discloses specific implementation conditions of the method and an aromatic compound structure type applicable to the method. The hydrogenation and hydrodeoxygenation reaction method used in the invention has the advantages of mild reaction conditions, high hydrodeoxygenation efficiency, wide substrate applicability, convenient post-treatment, and good laboratory and industrial application prospects.
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Paragraph 0094-0095; 0123-0125; 0127-0130
(2021/05/29)
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- Lignin Valorization by Cobalt-Catalyzed Fractionation of Lignocellulose to Yield Monophenolic Compounds
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Herein, a catalytic reductive fractionation of lignocellulose is presented using a heterogeneous cobalt catalyst and formic acid or formate as a hydrogen donor. The catalytic reductive fractionation of untreated birch wood yields monophenolic compounds in up to 34 wt % yield of total lignin, which corresponds to 76 % of the theoretical maximum yield. Model compound studies revealed that the main role of the cobalt catalyst is to stabilize the reactive intermediates formed during the organosolv pulping by transfer hydrogenation and hydrogenolysis reactions. Additionally, the cobalt catalyst is responsible for depolymerization reactions of lignin fragments through transfer hydrogenolysis reactions, which target the β-O-4′ bond. The catalyst could be recycled three times with only negligible decrease in efficiency, showing the robustness of the system.
- Rautiainen, Sari,Di Francesco, Davide,Katea, Sarmad Naim,Westin, Gunnar,Tungasmita, Duangamol N.,Samec, Joseph S. M.
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p. 404 - 408
(2019/01/04)
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- Depolymerization of lignin: Via a non-precious Ni-Fe alloy catalyst supported on activated carbon
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Lignin primarily composed of methoxylated phenylpropanoid subunits is an abundant biomass that can be used to produce aromatics. Herein, a series of non-precious bimetallic Ni-Fe/AC catalysts were prepared for efficiently depolymerizing lignin. When organosolv birch lignin was used to determine the efficiency of the catalysts in methanol solvent, the Ni1-Fe1/AC (the ratio of Ni and Fe was 1 : 1) achieved the highest total yield of monomers (23.2 wt%, mainly propylguaiacol and propylsyringol) at 225 °C under 2 MPa H2 for 6 h. From GPC analysis, it is also proved that lignin was efficiently depolymerized. The Ni-Fe alloy structure was formed according to XRD, HRTEM, H2-TPR and XPS characterization. Based on the model compounds' tests, the Ni1-Fe1/AC catalyst showed high efficiency in ether bond cleavage without hydrogenation of aromatic rings which could be attributed to the synergistic effect of Ni and Fe on the alloy structure. The total yield of monomers by using the Ni1-Fe1/AC catalyst reached 39.5 wt% (88% selectivity to PG and PS) when birch wood sawdust was used as the substrate.
- Zhai, Yongxiang,Li, Chuang,Xu, Guangyue,Ma, Yanfu,Liu, Xiaohao,Zhang, Ying
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p. 1895 - 1903
(2017/06/09)
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- Lignin depolymerization to monophenolic compounds in a flow-through system
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A reductive lignocellulose fractionation in a flow-through system in which pulping and transfer hydrogenolysis steps were separated in time and space has been developed. Without the hydrogenolysis step or addition of trapping agents to the pulping, it is possible to obtain partially depolymerized lignin (21 wt% monophenolic compounds) that is prone to further processing. By applying a transfer hydrogenolysis step 37 wt% yield of lignin derived monophenolic compounds was obtained. Pulp generated in the process was enzymatically hydrolyzed to glucose in 87 wt% yield without prior purification.
- Kumaniaev, Ivan,Subbotina, Elena,S?vmarker, Jonas,Larhed, Mats,Galkin, Maxim V.,Samec, Joseph S.M.
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p. 5767 - 5771
(2017/12/26)
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- Isolation of functionalized phenolic monomers through selective oxidation and CO bond cleavage of the β-O-4 linkages in Lignin
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Functionalized phenolic monomers have been generated and isolated from an organosolv lignin through a two-step depolymerization process. Chemoselective catalytic oxidation of β-O-4 linkages promoted by the DDQ/tBuONO/ O2 system was achieved in model compounds, including polymeric models and in real lignin. The oxidized β-O-4 linkages were then cleaved on reaction with zinc. Compared to many existing methods, this protocol, which can be achieved in one pot, is highly selective, giving rise to a simple mixture of products that can be readily purified to give pure compounds. The functionality present in these products makes them potentially valuable building blocks.
- Lancefield, Christopher S.,Ojo, O. Stephen,Tran, Fanny,Westwood, Nicholas J.
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p. 258 - 262
(2015/02/19)
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- A synergistic biorefinery based on catalytic conversion of lignin prior to cellulose starting from lignocellulosic biomass
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Current biomass utilization processes do not make use of lignin beyond its heat value. Here we report on a bimetallic Zn/Pd/C catalyst that converts lignin in intact lignocellulosic biomass directly into two methoxyphenol products, leaving behind the carbohydrates as a solid residue. Genetically modified poplar enhanced in syringyl (S) monomer content yields only a single product, dihydroeugenol. Lignin-derived methoxyphenols can be deoxygenated further to propylcyclohexane. The leftover carbohydrate residue is hydrolyzed by cellulases to give glucose in 95% yield, which is comparable to lignin-free cellulose (solka floc). New conversion pathways to useful fuels and chemicals are proposed based on the efficient conversion of lignin into intact hydrocarbons. This journal is
- Parsell, Trenton,Yohe, Sara,Degenstein, John,Jarrell, Tiffany,Klein, Ian,Gencer, Emre,Hewetson, Barron,Hurt, Matt,Kim, Jeong Im,Choudhari, Harshavardhan,Saha, Basudeb,Meilan, Richard,Mosier, Nathan,Ribeiro, Fabio,Delgass, W. Nicholas,Chapple, Clint,Kentt?maa, Hilkka I.,Agrawal, Rakesh,Abu-Omar, Mahdi M.
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p. 1492 - 1499
(2015/03/18)
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- CONTINUOUS PROCESS FOR CONVERSION OF LIGNIN TO USEFUL COMPOUNDS
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This specification discloses an operational continuous process to convert lignin as found in ligno-cellulosic biomass before or after converting at least some of the carbohydrates. The continuous process has been demonstrated to create a slurry comprised of lignin, raise the slurry comprised of lignin to ultra-high pressure, deoxygenate the lignin in a lignin conversion reactor over a catalyst which is not a fixed bed without producing char. The conversion products of the carbohydrates or lignin can be further processed into polyester intermediates for use in polyester preforms and bottles.
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Paragraph 0287-0293
(2013/09/12)
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- Catalytic conversion of biomass using solvents derived from lignin
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We report an approach by which the hemicellulose and cellulose fractions of biomass are converted through catalytic processes in a solvent prepared from lignin into high value platform chemicals and transportation fuels, namely furfural, 5-hydroxymethylfurfural, levulinic acid and γ-valerolactone. The Royal Society of Chemistry.
- Azadi, Pooya,Carrasquillo-Flores, Ronald,Pagan-Torres, Yomaira J.,Guerbuez, Elif I.,Farnood, Ramin,Dumesic, James A.
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supporting information
p. 1573 - 1576
(2013/02/23)
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- Determination of methoxyphenols in ambient atmospheric particulate matter: Tracers for wood combustion
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Combustion of wood and other biomass fuels produces source-specific organic compounds arising from pyrolysis of lignin, including substantial amounts of 4-substituted methoxylated phenolic compounds (methoxyphenols). These compounds have been used as atmospheric markers to determine the contribution of wood smoke to ambient atmospheric fine particulate matter (PM). However, reliable quantification of methoxyphenols represents an analytical challenge because these compounds are polar, semivolatile, and somewhat reactive. We report herein an improved gas chromatographic-mass spectrometric (GC/MS) method for the sensitive and reliable determination of methoxyphenols in low-volume ambient PM samples. Deuterated standard compounds are added to the environmental samples prior to extraction to determine analyte recoveries in each sample. Analytical figures of merit for the assay, as applied to ambient PM2.5 and PM10 samples are as follows: recovery = 63-100%; precision = 2-6%; analytical limit of detection (S/N 2) = 0.002 μg/mL; limit of quantitation = 0.07-0.45 ng/m3 (assuming a 14 m3 sample). The improved method was applied to ambient PM samples collected between 1999 and 2000 in Seattle, WA. Particle-bound methoxyphenol concentrations in the range 3 were observed and the methoxyphenols were present almost exclusively in the fine (PM2.5) size fraction. We also demonstrated that XRF analysis of samples of atmospheric PM collected on Teflon filters significantly reduced the levels of methoxyphenols measured in the PM samples in subsequent assay of the same filters. Therefore, XRF analysis of filters, commonly undertaken to obtain trace element concentrations for use in source apportionment analyses, would preclude the subsequent analysis of those filters for methoxyphenols and other similarly semivolatile or reactive organic chemicals.
- Simpson, Christopher D.,Paulsen, Michael,Dills, Russell L.,Liu, L.-J. Sally,Kalman, David A.
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p. 631 - 637
(2007/10/03)
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- Methoxyphenols from burning of Scandinavian forest plant materials
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Semivolatile compounds in smoke from gram-scale incomplete burning of plant materials were assessed by gas chromatography and mass spectrometry. Gas syringe sampling was shown to be adequate by comparison with adsorbent sampling. Methoxyphenols as well as 1,6-anhydroglucose were released in amounts as large as 10 mg kg-1 of dry biomass at 90% combustion efficiency. Wood, twigs, bark and needles from the conifers Norway spruce and Scots pine emitted 12 reported 2-methoxyphenols in similar proportions. Grass, heather and birchwood released the same 2-methoxyphenols but also the corresponding 2,6-dimethoxyphenols which are characteristic of angiosperms. The methoxyphenols are formed from lignin and differ in structure by the group in para position relative to the phenolic OH group. Prominent phenols were those with trans-l-propenyl and ethenyl groups in that position. Vanillin, 4- hydroxy-3-methoxybenzaldehyde, was a prominent carbonyl compound from the conifer materials. (C) 2000 Elsevier Science Ltd.
- Kjaellstrand, Jennica,Ramnaes, Olle,Petersson, Goeran
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p. 735 - 741
(2007/10/03)
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- Evaluation of acute toxicity and genotoxicity of liquid products from pyrolysis of Eucalyptus grandis wood
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Slow pyrolysis of Eucalyptus grandis wood was performed in an oven laboratory, and smoke was trapped and condensed to yield liquid products. Polycyclic aromatic hydrocarbons (PAHs) and phenolic fractions were isolated from the former liquid products using adsorption column chromatography (ACC) and identified by GC/MS. Concentrations of PAH and phenolic fractions in total pyrolysis liquids were respectively 48.9 μg/g and 8.59% (w/w). Acute toxicity of total samples of pyrolysis liquids and the phenolic fraction was evaluated by means of two bioassays, namely, 24-h immobilization bioassay with Daphnia magna and Microtox(TM) bioassays, the latter employing the luminescent bacteria Photobacterium phosphoreum. Total pyrolysis liquids and the PAH fraction were evaluated for genotoxicity by the Microtox(TM) bioassay conducted using rehydrated freeze-dried dark mutant of the luminescent bacteria Vibrio fisheri strain M169. Total pyrolysis liquids and the phenolic fraction, respectively, in concentrations of 170 and 68 mg/L were able to immobilize 50% (EC50) of the D. magna population following 24-h exposure. Concentrations of 19 and 6 mg/L, respectively, for total pyrolysis liquids and phenolic fraction were the effective concentrations that resulted in a 50% (EC50) reduction in light produced by bacteria in the Microtox(TM) bioassay. Accordingly, the Microtox(TM) bioassay was more sensitive to toxic effects of both kind of samples than the D. magna bioassay, particularly for the phenolic fraction. Regarding to the genotoxicity evaluation, the results achieved by Microtox(TM) bioassay showed that total pyrolysis liquids had no genotoxic effects with and without exogenous metabolic activation using rat liver homogenate (S9). However, the PAH fraction showed toxic effects with rat liver activation and had a dose-response number (DRN) equal to 1.6, being in this way suspected genotoxic. The lowest detected concentration (LDC) of the PAH fraction able to cause genotoxic effects was 375 μg/L.
- Pimenta,Bayona,Garcia,Solanas
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p. 169 - 175
(2007/10/03)
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- Stereoselective hydrogenation of lignin degradation model compounds
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Di-μ-chloro-bis(η4-1,5-hexadiene)dirhodium(I) in a two-phase hexane-aqueous medium catalyzes the diastereoselective H2-hydrogenation of lignin degradation model compounds 4-propylphenol, 2-methoxy-4-propylphenol, and 2,6-dimethoxy-4-propylphenol. The all-cis diastereomer is obtained selectively when the phenolic hydroxy group is protected as a methyl ether or when a model compound possessing two methoxy substituents adjacent to the phenolic hydroxy group is used. The relative stereochemistries of the hydrogenated products are established by X-ray crystal structure analysis and (or) 1H NMR.
- Hu,James,Rettig,Lee
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p. 1234 - 1239
(2007/10/03)
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- Formal Cycloaddition of Benzylic Cations with Alkenes
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The reaction of benzylic cations with styrenes affords dihydro(1H)indenes in good yield via a formal atom cycloadditon.The cations were generated from quinone methides and benzylic alcohols. (E)-Styrenes participate in the reaction with remarkable stereoselectivity affording dihydro(1H)indenes with three stereogenic centers with >40:1 diastereoselectivity.A possible transition state for the reaction is discussed.Less activated alkenes such as dihydropyran and methylcyclohexane afforded cycloadducts in 66percent and 51percent yields, respectively.
- Angle, Steven R.,Arnaiz, Damian O.
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p. 5937 - 5947
(2007/10/02)
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