scholarly journals Correction: Catalytic hydrogenolysis of kraft lignin to monomers at high yield in alkaline water

2017 ◽  
Vol 19 (17) ◽  
pp. 4186-4186 ◽  
Author(s):  
Shi-Chao Qi ◽  
Jun-ichiro Hayashi ◽  
Shinji Kudo ◽  
Lu Zhang
Keyword(s):  
Kraft Lignin ◽  
High Yield ◽  
Alkaline Water ◽  
Catalytic Hydrogenolysis

Correction for ‘Catalytic hydrogenolysis of kraft lignin to monomers at high yield in alkaline water’ by Shi-Chao Qi et al., Green Chem., 2017, 19, 2636–2645.

Catalytic hydrogenolysis of kraft lignin to monomers at high yield in alkaline water

2017 ◽  
Vol 19 (11) ◽  
pp. 2636-2645 ◽  
Author(s):  
Shi-Chao Qi ◽  
Jun-ichiro Hayashi ◽  
Shinji Kudo ◽  
Lu Zhang
Keyword(s):  
Kraft Lignin ◽  
High Yield ◽  
Alkaline Water ◽  
Catalytic Hydrogenolysis

The yield of hydrogenolytic depolymerization to the monomers of kraft lignin dissolved in alkaline water is largely increased by the pretreatment of stretching lignin macromolecules.

On the synthesis of 3,4-dihydroxyprolines. II. Synthesis, stereochemistry and reactivity of some 3,4-Epoxy-DL-proline derivatives

1975 ◽  
Vol 28 (11) ◽  
pp. 2479 ◽  
Author(s):  
CB Hudson ◽  
AV Robertson ◽  
WRJ Simpson
Keyword(s):  
Acid Hydrolysis ◽  
Methyl Esters ◽  
High Yield ◽  
Butyl Esters ◽  
Epoxy Acids ◽  
Trifluoroperacetic Acid ◽  
Catalytic Hydrogenolysis ◽  
Direct Separation ◽  
Proline Derivatives ◽  
Hydrolysis Of

N-Protected esters of 3,4-dehydro-DL-proline react with trifluoroperacetic acid to give, in high yield, approximately equal amounts of the corresponding stereoisomeric 3,4-epoxy-DL-proline derivatives, direct separation of which proved difficult. However individual members of the two families were obtained by discovery of selective transformations and fractionations. Relative configurations of the two 3,4-epoxy-N-tosylproline methyl esters were established by borohydride reduction to authentic 4-hydroxy-N-tosylprolinols. Epoxide reduction is regioselective. Extensive p.m.r. analyses then permitted stereochemical assignment of other derivatives. These epoxides are remarkably resistant to catalytic hydrogenolysis, and to hydration in acid or alkali. N-Substituted 3,4-epoxyproline methyl esters undergo ready β-elimination in alkali to yield the corresponding 4-hydroxy-2,3- dehydroproline esters and ultimately the N-substituted pyrrole-2- carboxylic acid or ester. Prolonged aqueous acid hydrolysis of 3,4- epoxy-N-tosylprolines, or of their methyl esters, gives mixtures of 3,4-dihydroxy-N-tosyl-DL-prolines in the 2,3-cis-3,4-trans and 2,3- trans-3,4-trans families. Their stereochemistry was allotted from p.m.r. of the diacetate methyl esters. During acid hydrolysis of 3,4- epoxy-N-tosylproline methyl esters, the ester of the trans stereoisomer hydrolyses selectively, and some epimerization of the cis stereoisomer occurs. Ester hydrolysis is much faster than epoxide hydration. Anhydrous acid cleavage of 3,4-epoxy-N-tosyl-DL-proline t-butyl esters to the epoxy acids is unusually slow.

scholarly journals Kraft Lignin Ethanolysis over Zeolites with Different Acidity and Pore Structures for Aromatics Production

Catalysts ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 270
Author(s):  
Nathan Cody Baxter ◽  
Yuxin Wang ◽  
Huijiang Huang ◽  
Yixin Liao ◽  
Heath Barnett ◽  
...  
Keyword(s):  
Pore Structure ◽  
Pore Size ◽  
High Volume ◽  
Kraft Lignin ◽  
High Yield ◽  
Hydrocarbon Cracking ◽  
Pore Structures ◽  
Strong Acidity ◽  
Micropore Size ◽  
Mesoporous Structures

To utilize its rich aromatics, lignin, a high-volume waste and environmental hazard, was depolymerized in supercritical ethanol over various zeolites types with different acidity and pore structures. Targeting at high yield/selectivity of aromatics such as phenols, microporous Beta, Y, and ZSM-5 zeolites were first examined in lignin ethanolysis, followed by zeolites with similar micropore size but different acidity. Further comparisons were made between zeolites with fin-like and worm-like mesoporous structures and their microporous counterparts. Despite depolymerization complexity and diversified ethanolysis products, strong acidity was found effective to cleave both C–O–C and C–C linkages of lignin while mild acidity works mainly in ether bond breakdown. However, when diffusion of gigantic molecules is severe, pore size, particularly mesopores, becomes more decisive on phenol selectivity. These findings provide important guidelines on future selection and design of zeolites with appropriate acidity and pore structure to promote lignin ethanolysis or other hydrocarbon cracking processes.

The synthesis of uridine diphosphate N-acetylhexosamines and uridine 5′-(2-acetamido-2-deoxy-α-D-mannopyranosyluronic acid diphosphate)

1981 ◽  
Vol 59 (15) ◽  
pp. 2247-2252 ◽  
Author(s):  
Tatsumi Yamazaki ◽  
Christopher D. Warren ◽  
Annette Herscovics ◽  
Roger W. Jeanloz
Keyword(s):  
Platinum Catalyst ◽  
Optical Rotation ◽  
Exchange Chromatography ◽  
High Yield ◽  
Uridine Diphosphate ◽  
Nmr Spectrum ◽  
H Nmr ◽  
Catalytic Hydrogenolysis ◽  
High Yields ◽  
Biosynthetic Studies

2-Methyl-(2-acetamido-3,4,6-tri-O-acetyl-l,2-dideoxy-β-D-mannopyrano)-[2,1-d]-2-oxazoline was efficiently converted into 2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-α-D-mannopyranosyl phosphate, by treatment with dibenzyl phosphate, followed by catalytic hydrogenolysis of the benzyl groups. Similarly, 2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-α-D-glucopyranosyl phosphate and -galactopyranosyl phosphate were synthesized from the respective peracetyl oxazolines. In each case, the procedures for preparing the oxazoline, and conversion into the glycosyl phosphate, were modified to give high yields of pure products. 2-Acetamido-3,4,6-tri-O-acetyl-2-deoxy-α-D-mannopyranosyl phosphate was coupled with 2′,3′-di-O-acetyluridine 5′-monophosphate by a modification of the mixed anhydride procedure, to give 2',3'-di-O-acetyluridine 5′-(2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-α-D-mannopyranosyl diphosphate), which was readily purified by preparative tic and O-deacetylated to give "uridine diphosphate N-acetylmannosamine" in high yield. Similarly, uridine 5′-(2-acetamido-2-deoxy-α-D-glucopyranosyl- and -galactopyranosyl diphosphates) were synthesized by rapid, efficient procedures, not involving ion-exchange chromatography. Uridine 5′-(2-acetamido-2-deoxy-α-D-mannopyranosyl diphosphate) was converted into uridine 5′-(2-acetamido-2-deoxy-α-D-mannopyranosyluronic acid diphosphate), required for biosynthetic studies, without the preparation of a special platinum catalyst. All the synthetic uridine diphosphate sugars were characterized by optical rotation, 1H nmr spectrum, and elemental analysis.

scholarly journals Biotransformation of Lignin by an Artificial Heme Enzyme Designed in Myoglobin With a Covalently Linked Heme Group

2021 ◽  
Vol 9 ◽  
Author(s):  
Wen-Jie Guo ◽  
Jia-Kun Xu ◽  
Jing-Jing Liu ◽  
Jia-Jia Lang ◽  
Shu-Qin Gao ◽  
...  
Keyword(s):  
Catalytic Mechanism ◽  
Plant Biomass ◽  
Enzymatic Catalysis ◽  
Kraft Lignin ◽  
High Yield ◽  
Artificial Enzyme ◽  
Renewable Chemicals ◽  
Heme Enzyme ◽  
Potential Applications ◽  
Covalently Linked

The conversion of Kraft lignin in plant biomass into renewable chemicals, aiming at harvesting aromatic compounds, is a challenge process in biorefinery. Comparing to the traditional chemical methods, enzymatic catalysis provides a gentle way for the degradation of lignin. Alternative to natural enzymes, artificial enzymes have been received much attention for potential applications. We herein achieved the biodegradation of Kraft lignin using an artificial peroxidase rationally designed in myoglobin (Mb), F43Y/T67R Mb, with a covalently linked heme cofactor. The artificial enzyme of F43Y/T67R Mb has improved catalytic efficiencies at mild acidic pH for phenolic and aromatic amine substrates, including Kraft lignin and the model lignin dimer guaiacylglycerol-β-guaiacyl ether (GGE). We proposed a possible catalytic mechanism for the biotransformation of lignin catalyzed by the enzyme, based on the results of kinetic UV-Vis studies and UPLC-ESI-MS analysis, as well as molecular modeling studies. With the advantages of F43Y/T67R Mb, such as the high-yield by overexpression in E. coli cells and the enhanced protein stability, this study suggests that the artificial enzyme has potential applications in the biodegradation of lignin to provide sustainable bioresource.

scholarly journals Unlocking the Catalytic Hydrogenolysis of Chlorosilanes into Hydrosilanes with Superbases

2021 ◽  
Author(s):  
Gabriel Durin ◽  
Jean-Claude Berthet ◽  
Emmanuel Nicolas ◽  
Thibault Cantat
Keyword(s):  
High Yield ◽  
Careful Selection ◽  
Efficient Synthesis ◽  
Nitrogen Base ◽  
Catalytic Hydrogenolysis ◽  
Sterically Hindered ◽  
Selection Of

The efficient synthesis of hydrosilanes by catalytic ydrogenolysis of chlorosilanes is described, using an Iridum (III) pincer catalyst. A careful selection of a nitrogen base (incl. sterically hindered guanidines and phosphazenes) can unlock the preparation of Me<sub>3</sub>SiH, Et<sub>3</sub>SiH and Me<sub>2</sub>SiHCl in high yield (up to 98%), directly from their corresponding chlorosilanes.

scholarly journals Integrated Cascade Biorefinery Processes to Transform Woody Biomass Into Phenolic Monomers and Carbon Quantum Dots

2021 ◽  
Vol 9 ◽  
Author(s):  
Xue Chen ◽  
Jiubin Zhu ◽  
Wenlu Song ◽  
Ling-Ping Xiao
Keyword(s):  
Quantum Dots ◽  
High Performance ◽  
Fluorescent Sensor ◽  
Hydrothermal Process ◽  
Value Added ◽  
Carbon Quantum Dots ◽  
High Yield ◽  
Heavy Metal Cations ◽  
Catalytic Hydrogenolysis ◽  
Cost Efficient

A novel cascade biorefinery strategy toward phenolic monomers and carbon quantum dots (CQDs) is proposed here via coupling catalytic hydrogenolysis and hydrothermal treatment. Birch wood was first treated with catalytic hydrogenolysis to afford a high yield of monomeric phenols (44.6 wt%), in which 4-propanol guaiacol (10.2 wt%) and 4-propanol syringol (29.7 wt%) were identified as the two major phenolic products with 89% selectivity. An available carbohydrate pulp retaining 82.4% cellulose and 71.6% hemicellulose was also obtained simultaneously, which was further used for the synthesis of CQDs by a one-step hydrothermal process. The as-prepared CQDs exhibited excellent selectivity and detection limits for several heavy metal cations, especially for Fe3+ ions in an aqueous solution. Those cost-efficient CQDs showed great potential in fluorescent sensor in situ environmental analyses. These findings provide a promising path toward developing high-performance sensors on environmental monitoring and a new route for the high value-added utilization of lignocellulosic biomass.

Thermocatalytic depolymerization of kraft lignin to guaiacols using HZSM-5 in alkaline water–THF co-solvent: a realistic approach

2019 ◽  
Vol 21 (14) ◽  
pp. 3864-3881 ◽  
Author(s):  
Deepak Raikwar ◽  
Saptarshi Majumdar ◽  
Debaprasad Shee
Keyword(s):  
Batch Reactor ◽  
Kraft Lignin ◽  
High Conversion ◽  
Alkaline Water ◽  
Structural Modifications ◽  
Realistic Approach

A study representing depolymerization of kraft lignin in a batch reactor with higher loading attaining high conversion and guaiacol selectivity simultaneously and its correlation with structural modifications.

scholarly journals High-Efficient and Recyclable Magnetic Separable Catalyst for Catalytic Hydrogenolysis of β-O-4 Linkage in Lignin

Polymers ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1077 ◽  
Author(s):  
Jingtao Huang ◽  
Chengke Zhao ◽  
Fachuang Lu
Keyword(s):  
Catalytic Performance ◽  
High Yield ◽  
Chemical Bonds ◽  
Aryl Ether ◽  
Structural Units ◽  
Great Abundance ◽  
High Efficient ◽  
Catalytic Hydrogenolysis ◽  
Potential Applications ◽  
Lignin Depolymerization

Lignin is recognized as a good sustainable material because of its great abundance and potential applications. At present, lignin hydrogenolysis is considered as a potential but challenging way to produce low-molecular-mass aromatic chemicals. The most common linkage between the structural units of lignin polymer is the β-O-4 aryl ether, which are primary or even only target chemical bonds for many degradation processes. Herein, a Pd-Fe3O4 composite was synthesized for catalytic hydrogenolysis of β-O-4 bond in lignin. The synthesized catalyst was characterized by XRD, XPS, and SEM and the lignin depolymerization products were analyzed by GC-MS. The catalyst showed good catalytic performance during the hydrogenolysis process, lignin dimer was degraded into monomers completely and a high yield of monomers was obtained by the hydrogenolysis of bagasse lignin. More importantly, the magnetic catalyst was separated conveniently by magnet after reaction and remained highly catalytically efficient after being reused for five times. This work has demonstrated an efficient & recyclable catalyst for the cleavage of the β-O-4 bond in lignin providing an alternative way to make better use of lignins.

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