scholarly journals Advanced Model Compounds for Understanding Acid-Catalyzed Lignin Depolymerization: Identification of Renewable Aromatics and a Lignin-Derived Solvent

2016 ◽  
Vol 138 (28) ◽  
pp. 8900-8911 ◽  
Author(s):  
Ciaran W. Lahive ◽  
Peter J. Deuss ◽  
Christopher S. Lancefield ◽  
Zhuohua Sun ◽  
David B. Cordes ◽  
...  
Keyword(s):  
Model Compounds ◽  
Acid Catalyzed ◽  
Lignin Depolymerization ◽  
Advanced Model

Kinetics and Mechanisms for the Isomerization of Internucleosidic 3'-O-P-CH2-5' and 3'-O-P-CH(OH)-5' Linkages to Their 2',5'-Counterparts

2006 ◽  
Vol 71 (6) ◽  
pp. 859-870 ◽  
Author(s):  
Tuomas Lönnberg ◽  
Šárka Králíková ◽  
Ivan Rosenberg ◽  
Harri Lönnberg
Keyword(s):  
Hydrogen Bond ◽  
Hydroxy Group ◽  
Phosphorus Atom ◽  
Hydrolytic Stability ◽  
Model Compounds ◽  
Hydroxide Ion ◽  
Wide Ph Range ◽  
Acid Catalyzed ◽  
Ph Range

Isomerization of internucleosidic 3'-O-P-CH2-5' and 3'-O-P-CH(OH)-5' phosphonate linkages to their 2',5'-counterparts has been studied over a wide pH-range. The model compounds employed are phosphonate analogs of adenylyl-(3',5')-adenosine and adenylyl-(2',5')-adenosine having either adenosine ((R,S)-1, (R,S)-2) or 5'-deoxyadenosine (3, 4) bonded to the phosphorus atom through the C5'-atom. For comparative purposes, the hydrolytic stability of C5'-hydroxyphosphonate analogs derived from 2'-deoxyadenosine ((R,S)-5) has also been studied. In addition to the expected acid-catalyzed (pH < 3) and pH-independent reactions (pH 3-9), the diastereomeric C5'-hydroxyphosphonate analogs ((R,S)-1, (R,S)-2), but not their deoxy counterparts (3, 4), have been observed to undergo a hydroxide-ion-catalyzed isomerization around pH 11 (90 °C). Evidently a hydrogen bond between the dianionic phosphorane and the C5'-hydroxy group stabilize the phosphorane to such an extent that isomerization via kinetically invisible protonation to monoanion becomes possible. The mechanisms of the isomerization reactions taking place under various conditions are discussed.

scholarly journals A Mechanistic Investigation of Acid-Catalyzed Cleavage of Aryl-Ether Linkages: Implications for Lignin Depolymerization in Acidic Environments

2013 ◽  
Vol 2 (3) ◽  
pp. 472-485 ◽  
Author(s):  
Matthew R. Sturgeon ◽  
Seonah Kim ◽  
Kelsey Lawrence ◽  
Robert S. Paton ◽  
Stephen C. Chmely ◽  
...  
Keyword(s):  
Aryl Ether ◽  
Mechanistic Investigation ◽  
Acid Catalyzed ◽  
Acidic Environments ◽  
Lignin Depolymerization

Kinetic Evidence for Predominant Oxygen Protonation of Amides

1972 ◽  
Vol 50 (5) ◽  
pp. 771-773 ◽  
Author(s):  
Clinton R. Smith ◽  
Keith Yates
Keyword(s):  
Strong Evidence ◽  
Rate Data ◽  
Model Compounds ◽  
Recent Proposal ◽  
Acid Catalyzed ◽  
Hydrolysis Of

Comparison of rate data for the acid-catalyzed hydrolysis of amides, and model compounds for O- and N-protonated amides, provides strong evidence that amides protonate predominantly on oxygen in dilute as well as in concentrated aqueous acids, contrary to a recent proposal that the protonation sites are different in the two media.

In-situ hydrogenation of lignin depolymerization model compounds to cyclohexanol

2013 ◽  
Vol 41 (4) ◽  
pp. 443-447 ◽  
Author(s):  
Yu-xiao YU ◽  
Ying XU ◽  
Tie-jun WANG ◽  
Long-long MA ◽  
Qi ZHANG ◽  
...  
Keyword(s):  
Model Compounds ◽  
Lignin Depolymerization

Tungsten-based catalysts for lignin depolymerization: the role of tungsten species in C–O bond cleavage

2019 ◽  
Vol 9 (9) ◽  
pp. 2144-2151 ◽  
Author(s):  
Haiwei Guo ◽  
Zaojuan Qi ◽  
Yuxuan Liu ◽  
Haian Xia ◽  
Lin Li ◽  
...  
Keyword(s):  
Bond Cleavage ◽  
Model Compounds ◽  
Lignin Model Compounds ◽  
Tungsten Species ◽  
Lignin Model ◽  
Lignin Depolymerization

Tungsten-based catalysts with designed tungsten species are synthesized and the role of each species in hydrocracking of both lignin model compounds and real lignin is deeply studied.

scholarly journals Selective hydrogenolysis of catechyl lignin into propenylcatechol over an atomically dispersed ruthenium catalyst

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Shuizhong Wang ◽  
Kaili Zhang ◽  
Helong Li ◽  
Ling-Ping Xiao ◽  
Guoyong Song
Keyword(s):  
Small Molecules ◽  
Model Compounds ◽  
Efficient Catalyst ◽  
Selective Catalyst ◽  
Ru Catalyst ◽  
Significant Interest ◽  
Selective Hydrogenolysis ◽  
Dehydrogenation Reactions ◽  
High Yields ◽  
Lignin Depolymerization

AbstractC-lignin is a homo-biopolymer, being made up of caffeyl alcohol exclusively. There is significant interest in developing efficient and selective catalyst for depolymerization of C-lignin, as it represents an ideal feedstock for producing catechol derivatives. Here we report an atomically dispersed Ru catalyst, which can serve as an efficient catalyst for the hydrogenolysis of C-lignin via the cleavage of C−O bonds in benzodioxane linkages, giving catechols in high yields with TONs up to 345. A unique selectivity to propenylcatechol (77%) is obtained, which is otherwise hard to achieve, because this catalyst is capable of hydrogenolysis rather than hydrogenation. This catalyst also demonstrates good reusability in C-lignin depolymerization. Detailed investigations by model compounds concluded that the pathways involving dehydration and/or dehydrogenation reactions are incompatible routes; we deduced that caffeyl alcohol generated via concurrent C−O bonds cleavage of benzodioxane unit may act as an intermediate in the C-lignin hydrogenolysis. Current demonstration validates that atomically dispersed metals can not only catalyze small molecules reactions, but also drive the transformation of abundant and renewable biopolymer.

scholarly journals Aromatic dimer dehydrogenases from Novosphingobium aromaticivorans reduce monoaromatic diketones

2021 ◽  
Author(s):  
Alexandra M. Linz ◽  
Yanjun Ma ◽  
Jose M. Perez ◽  
Kevin S. Myers ◽  
Wayne S. Kontur ◽  
...  
Keyword(s):  
Potential Range ◽  
Industrial Chemicals ◽  
Multiple Substrates ◽  
Chemically Modified ◽  
Genome Wide ◽  
Wide Range ◽  
Acid Catalyzed ◽  
Plant Polymer ◽  
Lignin Depolymerization

Lignin is a potential source of valuable chemicals, but its chemical depolymerization results in a heterogeneous mixture of aromatics and other products. Microbes could valorize depolymerized lignin by converting multiple substrates into one or a small number of products. In this study, we describe the ability of Novosphingobium aromaticivorans to metabolize 1-(4-hydroxy-3-methoxyphenyl)propane-1,2-dione (G-diketone), an aromatic Hibbert diketone which is produced during formic acid-catalyzed lignin depolymerization. By assaying genome-wide transcript levels from N. aromaticivorans during growth on G-diketone and other chemically-related aromatics, we hypothesized that the Lig dehydrogenases, previously characterized as oxidizing β-O-4 linkages in aromatic dimers, were involved in G-diketone metabolism by N. aromaticivorans . Using purified N. aromaticivorans Lig dehydrogenases, we found that LigL, LigN, and LigD each reduced the Cα ketone of G-diketone in vitro but with different substrate specificities and rates. Furthermore, LigL, but not LigN or LigD, also reduced the Cα ketone of 2-hydroxy-1-(4-hydroxy-3-methoxyphenyl)propan-1-one (GP-1) in vitro , a derivative of G-diketone with the Cβ ketone reduced, when GP-1 was provided as a substrate. The newly identified activity of these Lig dehydrogenases expands the potential range of substrates utilized by N. aromaticivorans beyond what has been previously recognized. This is beneficial both for metabolizing a wide range of natural and non-native depolymerized lignin substrates and for engineering microbes and enzymes that are active with a broader range of aromatic compounds. Importance Lignin is a major plant polymer composed of aromatic units that have value as chemicals. However, the structure and composition of lignin has made it difficult to use this polymer as a renewable source of industrial chemicals. Bacteria like Novosphingobium aromaticivorans have the potential to make chemicals from lignin not only because of their natural ability to metabolize a variety of aromatics but also because there are established protocols to engineer N. aromaticivorans strains to funnel lignin-derived aromatics into valuable products. In this work, we report a newly discovered activity of previously characterized dehydrogenase enzymes with a chemically-modified byproduct of lignin depolymerization. We propose that the activity of N. aromaticivorans enzymes with both native lignin aromatics and those produced by chemical depolymerization will expand opportunities for producing industrial chemicals from the heterogenous components of this abundant plant polymer.

Acid-catalyzed Cycloaromatization of Enediyne Model Compounds via Enyne-Allene Intermediates

Heterocycles ◽  
2001 ◽  
Vol 54 (2) ◽  
pp. 571 ◽  
Author(s):  
Masayuki Shibuya ◽  
Ichiro Suzuki ◽  
Akira Shigenaga ◽  
Hisao Nemoto
Keyword(s):  
Model Compounds ◽  
Acid Catalyzed

ChemInform Abstract: Acid-Catalyzed Cycloaromatization of Enediyne Model Compounds via Enyne-Allene Intermediates.

ChemInform ◽  
2010 ◽  
Vol 32 (26) ◽  
pp. no-no
Author(s):  
Ichiro Suzuki ◽  
Akira Shigenaga ◽  
Hisao Nemoto ◽  
Masayuki Shibuya
Keyword(s):  
Model Compounds ◽  
Acid Catalyzed
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