2 edition of Reduction of lignin model compounds by trivalent uranium found in the catalog.
Reduction of lignin model compounds by trivalent uranium
Samuel Hugh Hawthorne
Written in English
|Contributions||Toronto, Ont. University.|
|The Physical Object|
|Number of Pages||196|
3. Lignin Model Compounds and Product Streams H -O-4 Linkage Model Compounds H Carbon-Carbon Linkage Model Compounds I -5 Linkage Model Compounds J R-O-4 and 4-O-5 Linkage Model Compounds K p-Coumaryl, Coniferyl, And Sinapyl Alcohol Model Compounds M General Considerations N 4. Bioreﬁneries Revisited P 5. Lignin. The potential of lignin is therefore quite high: besides cellulose and chitin, lignin is the most abundant polymer in nature - and the only one that contains such a large number of aromatic compounds. Every year, approximately 50 million tonnes of lignin are produced worldwide as by-products of the paper industry.
Lignin peroxidase (LiP) was first discovered based on the H 2 O 2-dependent C a -C ß cleavage of lignin model compounds and subsequently shown to catalyze depolymerization of methylated lignin in vitro (Glenn et al. ; Tien and Kirk , ; Gold et al. ). Multiple isozymes of LiP are. Scientists in China have developed a method to produce ethanol using the renewable resources lignin and carbon dioxide for the first time. The process uses a ruthenium–cobalt catalyst and.
The authors used photoelectron spectroscopy to determine ionization potentials of 64 lignin model compounds. This data provides an indication of the relative reactivity of these lignin subunits. 3. Oxidation of lignin model compounds Experimental procedures: The oxidation reactions were conducted in a Teflon-lined stainless steel reactor of 10 mL, which was similar tothat used previously.2 In the experiment, desired amount of IL, acid (e.g. H3PO4) aqueous solution, lignin model compound or lignin, and water were added in the reactor.
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Reaction network for the conversion of lignin model compounds (each compound shown in red was used as a reactant) with H 2 catalyzed by Pt/γ-Al 2 O 3 at K and kPa. (For interpretation of the references to color in this figure legend, the reader is Cited by: An efficient and straightforward reaction protocol for the conversion of lignin model compounds was developed based on a simple system consisting of a base, oxygen, and a green solvent under mild conditions in the absence of metals.
This protocol was successfully applied to the cleavage of both ‘β Cited by: 6. Preliminary studies were conducted on the degradation of guaiacylglycerol‐β‐aryl ether (β‐O‐4′), phenylcoumaran (β‐5′) and biphenyl (5–5′) type lignin model compounds in the organic solvent systems such as ethanol‐water (, v/v) and 2‐butanone‐water (, v/v), in the presence of a di‐ or trivalent inorganic salt to act as a Lewis acid in the temperature range Cited by: 4.
The basic mechanistic aspects of the photo- and radiation chemistry of lignin model compounds have been discussed with respect to important processes related to lignin degradation. The studies have been divided in three sections: Direct photochemical irradiation, photosensitized oxidation and radiation chemistry of lignin model by: The Chemistry of Lignin provides a critical review of the literature published from to This book provides information pertinent to the fundamental aspects of lignin chemistry.
Organized into 27 chapters, this book begins with an overview of the derivatives that are prepared for the characterization of the mother Edition: 1. Effects of Alkoxy Groups on Arene Rings of Lignin β-O-4 Model Compounds on the Efficiencies of Single Electron Transfer-Promoted Photochemical and Enzymatic C–C Bond Cleavage Reactions.
The Journal of Organic Chemistry78 (18), Lignin model compounds were decomposed in a batch reactor made of stainless steel tube with an inner volume of cm 3 in the similar method for lignin.
Lignin model compounds have a large number of phenolic pyrolysis products, most likely due to the low strength of the bond to form phenol or catechol compounds. Ether Bond Strength Calculations in Model Dimer Molecule. The G-type dimers were optimized by MP2/G, and the bond energy, bond length, and other structural parameters of the.
Lignin, the planet's most abundant renewable source of aromatic compounds, is difficult to degrade efficiently to welldefined aromatics. We developed a microwave‐assisted catalytic Swern oxidation system using an easily prepared catalyst, MoO 2 Cl 2 (DMSO) 2, and DMSO as the solvent and demonstrated high efficiency in transforming lignin model compounds containing the units and.
Biphenyl Type Lignin Model Compounds", Journal of Wood Chemistry and Technology, 9 (4),().]. Table lists an extensive compilation of structural assignments that have been derived from model compound studies.
The major disadvantage of 13C–NMR spectroscopy is the inherent low sensitivity which requires that a large sample size and a. the dominant structures in lignin have been elucidated as the methods for identification of the degradation products and for the synthesis of model compounds have improved.
The results from these numerous studies have yielded what is believed to be an accurate representation of the structure of lignin. Lignins are nature’s aromatic polymers and are the second most abundant organic constituent of the biosphere next to cellulose. Lignification mainly occurs in the walls of terrestrial vascular plants, mainly in the secondarily thickened cells of supportive or conductive tissues, which thus acquire novel properties.
This new volume of Advances in Botanical Research gives a special emphasis to. Lignin, a major component of lignocellulose, is the largest source of aromatic building blocks on the planet and harbors great potential to serve as starting material for the production of biobased products.
Despite the initial challenges associated with the robust and irregular structure of lignin, the valorization of this intriguing aromatic biopolymer has come a long way: recently, many.
There are many reported lignin model compounds, such as ferulic acid, vanillyl alcohol isoeugenol, and benzyl alco We selected lignin dimer as a representative model.
In general terms, wood, lignin and lignin model compounds reduced Cr(VI) faster and to a greater extent than polysaccharides or simple sugar molecules.
Moreover, lignin model compounds were. The oxidation of lignin model compounds was studied in conventional solvents in parallel with oxidations in ionic liquid solvents.
Catalyst systems were investigated in ionic liquid solvents to determine how reaction rates and the selectivity for benzylic carbon oxidation were.
Table Selective Lewis acid-assisted oxidation of lignin model compound A. Table Oxidation of simple β-O-4 model compound C (1-phenylphenoxyethanol). Chapter 3: Table Lewis acid-assisted oxidation of lignin model compound A with iodosobenzene as oxidant. Table Oxidation of lignin model compound A with iodosoperfluorobenzene and.
Cleaving the β O 4 Bonds of Lignin Model Compounds in an Acidic Ionic Liquid, 1-HMethylimidazolium Chloride: An Optional Strategy for the Degradation of Lignin journal, July Jia, Songyan; Cox, Blair J.; Guo, Xinwen; ChemSusChem, Vol.
3, Issue 9; DOI: /cssc OXIDATION OF -O-4 LIGNIN MODEL COMPOUNDS AND APPLICATION TO LIGNIN LINKAGE DEGRADATION FACILITATED BY MECHANOCHEMICAL TREATMENT AND TWO-STEP OXIDATIVE DEPOLYMERIZATION The oxidation of lignin model compounds was studied in conventional solvents in parallel with oxidations in ionic liquid solvents.
Full Article. Ionic Liquids and Organic Solvents for Recovering Lignin from Lignocellulosic Biomass. José Luis Espinoza-Acosta, a, * Patricia Isabel Torres-Chávez, a, * Elizabeth Carvajal-Millán, b Benjamín Ramírez-Wong, a Luis Arturo Bello-Pérez, c and Beatriz Montaño-Leyva d Lignin contributes to the recalcitrance of lignocellulosic biomass and affects enzymatic activity during.
Modern concepts of lignin structure suggest that the ketol 1-hydroxy(4-hydroxymethoxyphenyl)propanone, VI, should be detectable in the hydrolysis products of lignin and wood.
A reference sample of VI, previously unavailable, has now been prepared by catalytic hydrogenation of the diketone 1-(4-hydroxymethoxyphenyl)-1,2-propanedione, II.Lignin in Polymer Composites presents the latest information on lignin, a natural polymer derived from renewable resources that has great potential as a reinforcement material in composites because it is non-toxic, inexpensive, available in large amounts, and is starting to be deployed in various materials applications due to its advantages over more traditional oil-based materials.A synthetic method for obtaining lignin oligomer that contains only the β-O-4 structure is described in detail.
This method consists of three reaction steps: (1) the synthesis of t-butoxycarbonylmethyl vanillin (2), (2) the nucleophilic addition oligomerization of compound 2, and (3) the reduction of the oligomeric β-hydroxyl ester. In the first step, compound 2 was synthesized from vanillin.