scholarly journals Catalytic Liquefaction of Kraft Lignin with Solvothermal Approach

Catalysts ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 875
Author(s):  
Woldemichael Sebhat ◽  
Ayman El Roz ◽  
Pascal Fongarland ◽  
Léa Vilcocq ◽  
Laurent Djakovitch
Keyword(s):  
Palladium Catalysts ◽  
31P Nmr ◽  
Inert Atmosphere ◽  
Kraft Lignin ◽  
Chemical Transformations ◽  
Paper Pulp ◽  
Solid Catalysts ◽  
Kraft Process ◽  
The Impact ◽  
Water Alcohol

Lignin is a natural biopolymer present in lignocellulosic biomass. During paper pulp production with the Kraft process, it is solubilized and degraded in Kraft lignin and then burned to recover energy. In this paper, the solvolysis of Kraft lignin was studied in water and in water/alcohol mixtures to produce oligomers and monomers of interest, at mild temperatures (200–275 °C) under inert atmosphere. It was found that the presence of alcohol and the type of alcohol (methanol, ethanol, isopropanol) greatly influenced the amount of oligomers and monomers formed from lignin, reaching a maximum of 48 mg·glignin−1 of monomers with isopropanol as a co-solvent. The impact of the addition of various solid catalysts composed of a metal phase (Pd, Pt or Ru) supported on an oxide (Al2O3, TiO2, ZrO2) was investigated. In water, the yield in monomers was enhanced by the presence of a catalyst and particularly by Pd/ZrO2. However, with an alcoholic co-solvent, the catalyst only enhanced the formation of oligomers. Detailed characterizations of the products with FTIR, 31P-NMR, 1H-NMR and HSQC NMR were performed to elucidate the chemical transformations occurring during solvolysis. The nature of the active catalytic specie was also investigated by testing homogeneous palladium catalysts.

Biotransformation of Coumarins by Filamentous Fungi: An Alternative Way for Achievement of Bioactive Analogs

2019 ◽  
Vol 16 (6) ◽  
pp. 568-577 ◽  
Author(s):  
Jainara Santos do Nascimento ◽  
João Carlos Silva Conceição ◽  
Eliane de Oliveira Silva
Keyword(s):  
Filamentous Fungi ◽  
Chemical Reactions ◽  
Biological Activities ◽  
Chemical Transformations ◽  
Chemical Structures ◽  
Pattern Structures ◽  
Pharmacological Interest ◽  
Aspergillus Sp ◽  
The Impact ◽  
Related Compounds

Coumarins are natural 1,2-benzopyrones, present in remarkable amounts as secondary metabolites in edible and medicinal plants. The low yield in the coumarins isolation from natural sources, along with the difficulties faced by the total synthesis, make them attractive for biotechnological studies. The current literature contains several reports on the biotransformation of coumarins by fungi, which can generate chemical analogs with high selectivity, using mild and eco-friendly conditions. Prompted by the enormous pharmacological interest in the coumarin-related compounds, their alimentary and chemical applications, this review covers the biotransformation of coumarins by filamentous fungi. The chemical structures of the analogs were presented and compared with those from the pattern structures. The main chemical reactions catalyzed the insertion of functional groups, and the impact on the biological activities caused by the chemical transformations were discussed. Several chemical reactions can be catalyzed by filamentous fungi in the coumarin scores, mainly lactone ring opening, C3-C4 reduction and hydroxylation. Chunninghamella sp. and Aspergillus sp. are the most common fungi used in these transformations. Concerning the substrates, the biotransformation of pyranocoumarins is a rarer process. Sometimes, the bioactivities were improved by the chemical modifications and coincidences with the mammalian metabolism were pointed out.

scholarly journals Reactivity of Aliphatic and Phenolic Hydroxyl Groups in Kraft Lignin towards 4,4′ MDI

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2131
Author(s):  
Leonardo Dalseno Antonino ◽  
Júlia Rocha Gouveia ◽  
Rogério Ramos de Sousa Júnior ◽  
Guilherme Elias Saltarelli Garcia ◽  
Luara Carneiro Gobbo ◽  
...  
Keyword(s):  
Experimental Work ◽  
Chemical Structure ◽  
31P Nmr ◽  
Kraft Lignin ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Diphenylmethane Diisocyanate ◽  
Complex Chemical ◽  
Heterogeneous Reactivity ◽  
Phenolic Hydroxyl Groups

Several efforts have been dedicated to the development of lignin-based polyurethanes (PU) in recent years. The low and heterogeneous reactivity of lignin hydroxyl groups towards diisocyanates, arising from their highly complex chemical structure, limits the application of this biopolymer in PU synthesis. Besides the well-known differences in the reactivity of aliphatic and aromatic hydroxyl groups, experimental work in which the reactivity of both types of hydroxyl, especially the aromatic ones present in syringyl (S-unit), guaiacyl (G-unit), and p-hydroxyphenyl (H-unit) building units are considered and compared, is still lacking in the literature. In this work, the hydroxyl reactivity of two kraft lignin grades towards 4,4′-diphenylmethane diisocyanate (MDI) was investigated. 31P NMR allowed the monitoring of the reactivity of each hydroxyl group in the lignin structure. FTIR spectra revealed the evolution of peaks related to hydroxyl consumption and urethane formation. These results might support new PU developments, including the use of unmodified lignin and the synthesis of MDI-functionalized biopolymers or prepolymers.

scholarly journals Chemical interactions between ship-originated air pollutants and ocean-emitted halogens

2021 ◽  
Author(s):  
Qinyi Li ◽  
Alba Badia ◽  
Rafael P. Fernandez ◽  
Anoop S. Mahajan ◽  
Ana Isabel López-Noreña ◽  
...  
Keyword(s):  
Air Pollutants ◽  
Atmospheric Composition ◽  
Chemical Transformations ◽  
Chemical Interactions ◽  
China Sea ◽  
Reactive Halogen Species ◽  
The Impact ◽  
Surface Increase ◽  
Halogen Species

<p>Ocean-going ships supply products from one region to another and contribute to the world’s economy. Ship exhaust contains many air pollutants and results in significant changes in marine atmospheric composition. The role of Reactive Halogen Species (RHS) in the troposphere has received increasing recognition and oceans are the largest contributors to their atmospheric burden. However, the impact of shipping emissions on RHS and that of RHS on ship-originated air pollutants have not been studied in detail. Here, an updated WRF-Chem model is utilized to explore the chemical interactions between ship emissions and oceanic RHS over the East Asia seas in summer. The emissions and resulting chemical transformations from shipping activities increase the level of NO and NO<sub>2</sub> at the surface, increase O<sub>3</sub> in the South China Sea, but decrease O<sub>3</sub> in the East China Sea. Such changes in pollutants result in remarkable changes in the levels of RHS as well as in their partitioning. The abundant RHS, in turn, reshape the loadings of air pollutants and those of the oxidants with marked patterns along the ship tracks. We, therefore, suggest that these important chemical interactions of ship-originated emissions with RHS should be considered in the environmental policy assessments of the role of shipping emissions in air quality and climate.</p>

Role of mesopores in Co/ZSM-5 for the direct synthesis of liquid fuel by Fischer–Tropsch synthesis

2018 ◽  
Vol 8 (24) ◽  
pp. 6346-6359 ◽  
Author(s):  
Ji-Eun Min ◽  
Sungtak Kim ◽  
Geunjae Kwak ◽  
Yong Tae Kim ◽  
Seung Ju Han ◽  
...  
Keyword(s):  
Mass Transfer ◽  
Pore Structure ◽  
Liquid Fuel ◽  
Direct Synthesis ◽  
Reaction System ◽  
Complex Reaction ◽  
Fischer Tropsch ◽  
Solid Catalysts ◽  
The Impact

In a complex reaction system, in which gas, liquid, and solid catalysts work together, understanding the impact of mass transfer that varies with the catalyst pore structure is very challenging but also essential to designing selective catalysts.

scholarly journals BETULIN-3, 28-DIPHOSPHATE SALT COMPLEXES WITH AMINES AND THEIR ANTIOXIDANT ACTIVITY

2018 ◽  
Vol 10 (2) ◽  
pp. 87 ◽  
Author(s):  
Nina Melnikova ◽  
Darina S. Malygina ◽  
Olga N. Solovyeva ◽  
Olga E. Zhiltsova ◽  
Victor A. Vasin ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
31P Nmr ◽  
Antioxidant Properties ◽  
Conditional Stability ◽  
Hydrazine Sulfate ◽  
Sod Activity ◽  
Conditional Stability Constant ◽  
Alcohol Medium ◽  
Water Alcohol

Objective: Studies of composition, stability and antioxidant properties of the betulin-3, 28-diphosphate complexes with dopamine and trisamine.Methods: The betulin-3, 28-diphosphate (BDP) interaction with amines in a water-alcohol medium was studied by using spectral methods and potentiometric titration. Biochemical indexes such as catalase, superoxide dismutase (SOD), lactate dehydrogenase (LDH) activities and malondialdehyde (MDA) level were estimated in experiments on rats.Results: BDP was synthesized using betulin by POCl3 treatment in the presence of pyridine in dioxane. The complexation of BDP with amines was confirmed by the 31P-NMR and FTIR-spectral data. The stoichiometry of BDP-dopamine complexes was equal to 2:1 and 4:1 and its complexes with trisamine were produced in the ratio 1:1 in a water-alcohol medium. The conditional stability constant К′st of the BDP-trisamine complex is 1130±55 mol∙l-1. BDP-Tris complex improved SOD activity up to 30% and up to 105% in the presence of cytostatic-hydrazine sulfate. The MDA level in erythrocytes decreased up to 57% and in combination with cytostatics (5-fluorouracil and hydrazine sulfate)-up to 11-14%. The catalase activity increased by 44-94% and MDA level in erythrocytes decreased by 22-53% under the action BDP-DA complexes that depends on the dose.Conclusion: The BDP forms stable complexes with trisamine and dopamine that make it possible to use this compound as a component of drug delivery system for high toxicity cytostatics and for readily oxidized catecholamines. It has been shown that both its complexes with amines and the combination with cytostatics enhanced antioxidant activity in an experiment in vitro.

scholarly journals Brominated VSLS and their influence on ozone under a changing climate

2017 ◽  
Vol 17 (18) ◽  
pp. 11313-11329 ◽  
Author(s):  
Stefanie Falk ◽  
Björn-Martin Sinnhuber ◽  
Gisèle Krysztofiak ◽  
Patrick Jöckel ◽  
Phoebe Graf ◽  
...  
Keyword(s):  
21St Century ◽  
Atmospheric Chemistry ◽  
Lower Stratosphere ◽  
Atmospheric Transport ◽  
Stratospheric Ozone ◽  
Chemical Transformations ◽  
Mixing Ratios ◽  
Ocean Atmosphere ◽  
The Impact

Abstract. Very short-lived substances (VSLS) contribute as source gases significantly to the tropospheric and stratospheric bromine loading. At present, an estimated 25 % of stratospheric bromine is of oceanic origin. In this study, we investigate how climate change may impact the ocean–atmosphere flux of brominated VSLS, their atmospheric transport, and chemical transformations and evaluate how these changes will affect stratospheric ozone over the 21st century. Under the assumption of fixed ocean water concentrations and RCP6.0 scenario, we find an increase of the ocean–atmosphere flux of brominated VSLS of about 8–10 % by the end of the 21st century compared to present day. A decrease in the tropospheric mixing ratios of VSLS and an increase in the lower stratosphere are attributed to changes in atmospheric chemistry and transport. Our model simulations reveal that this increase is counteracted by a corresponding reduction of inorganic bromine. Therefore the total amount of bromine from VSLS in the stratosphere will not be changed by an increase in upwelling. Part of the increase of VSLS in the tropical lower stratosphere results from an increase in the corresponding tropopause height. As the depletion of stratospheric ozone due to bromine depends also on the availability of chlorine, we find the impact of bromine on stratospheric ozone at the end of the 21st century reduced compared to present day. Thus, these studies highlight the different factors influencing the role of brominated VSLS in a future climate.

scholarly journals Impact of Inhibition of the Mitochondrial Pyruvate Carrier on the Tumor Extracellular pH as Measured by CEST-MRI

Cancers ◽  
2021 ◽  
Vol 13 (17) ◽  
pp. 4278
Author(s):  
Chloé Buyse ◽  
Nicolas Joudiou ◽  
Cyril Corbet ◽  
Olivier Feron ◽  
Lionel Mignion ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
31P Nmr ◽  
Glucose Consumption ◽  
Extracellular Ph ◽  
31P Nmr Spectroscopy ◽  
Parametric Images ◽  
Mitochondrial Pyruvate Carrier ◽  
Cest Mri ◽  
The Impact

(1) Background: The acidosis of the tumor micro-environment may have profound impact on cancer progression and on the efficacy of treatments. In the present study, we evaluated the impact of a treatment with UK-5099, a mitochondrial pyruvate carrier (MPC) inhibitor on tumor extracellular pH (pHe); (2) Methods: glucose consumption, lactate secretion and extracellular acidification rate (ECAR) were measured in vitro after exposure of cervix cancer SiHa cells and breast cancer 4T1 cells to UK-5099 (10 µM). Mice bearing the 4T1 tumor model were treated daily during four days with UK-5099 (3 mg/kg). The pHe was evaluated in vivo using either chemical exchange saturation transfer (CEST)-MRI with iopamidol as pHe reporter probe or 31P-NMR spectroscopy with 3-aminopropylphosphonate (3-APP). MR protocols were applied before and after 4 days of treatment; (3) Results: glucose consumption, lactate release and ECAR were increased in both cell lines after UK-5099 exposure. CEST-MRI showed a significant decrease in tumor pHe of 0.22 units in UK-5099-treated mice while there was no change over time for mice treated with the vehicle. Parametric images showed a large heterogeneity in response with 16% of voxels shifting to pHe values under 7.0. In contrast, 31P-NMR spectroscopy was unable to detect any significant variation in pHe; (4) Conclusions: MPC inhibition led to a moderate acidification of the extracellular medium in vivo. CEST-MRI provided high resolution parametric images (0.44 µL/voxel) of pHe highlighting the heterogeneity of response within the tumor when exposed to UK-5099.

PELEPASAN TINTA PADA KERTAS NCR (NO CARBON REQUIRED) BEKAS DAN KERTAS UANG MENGGUNAKAN XILANASE

2013 ◽  
Vol 13 (3) ◽  
Author(s):  
Trismilah Trismilah
Keyword(s):  
Polymer Coating ◽  
Pulp And Paper ◽  
Bacillus Sp ◽  
Paper Pulp ◽  
E Coli ◽  
Paper Money ◽  
Proficiency Level ◽  
Pulp Paper ◽  
Virgin Pulp ◽  
The Impact

Recycling paper is a solution to overcome the depletion of virgin pulp from trees and reduce the impact of global warming. Deinking paper is very important in the process of recycling paper. Xylanase application of research required for deinking outworn NCR paper and paper money. Deinking enzymatic is a clean technology and produces less waste than conventional deinking (chemicals). Xylanase AQ-1 which is a crude enzyme from Bacillus sp isolates AQ-1 can work well in the deinking process on the amount of enzyme addition of 0.2% in the pulp with the conditions of pH 7 and temperature of 50oC for 120 minutes. While the recombinant xylanase AQ-1 which is the result of genetic xylanase AQ-1 grown in E. coli can work well in the deinking process on the amount of enzyme addition of 0.1% in the pulp with the conditions of pH 7 and temperature of 50oC for 60 minutes. Xylanase AQ-1 increases the degree of whiteness of green NCR paper pulp from the control (40.1) into (53.9) and pulp paper moneyof the control (50.1) into (66.6). While AQ-1 recombinant xylanase increases the degree of whiteness of green NCR paper pulp from control ( 40.1) into (52.0) pulp and paper money from the control (50.1) into (63.4). Xylanase AQ-1 and recombinant xylanase AQ-1 potential in the green NCR paper deinking and paper deinking paper money, although the money still leaves some smudges on the results because of a special polymer coating that coats the waterproof paper money proficiency level.

C-Methylation Of Organic Substrates: A Comprehensive Overview. Part Ii. Methanol As Methylating Agent. A Case Of Catalysis Versatility

2020 ◽  
Vol 17 ◽  
Author(s):  
Saad Moulay
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Molecular Sieves ◽  
Acid Sites ◽  
Lewis Base ◽  
Molar Ratio ◽  
Organic Substrates ◽  
Solid Catalysts ◽  
The Impact

: The present account surveys the results of the myriad of works on C-methylation of organic substrates with methanol as an eco-friendly methylating agent. The innumerable reports on this issue reveal the widespread use of a set of solid catalysts such as molecular sieves, zeolites, metal phosphates, metal oxides and transition metal complexes, to accomplish such methylation. One related facet was the impact of the numbers of Brønstëd acid sites, of Lewis acid sites, and of Lewis base sites present in solid catalysts, such as zeolites, their ratios, and their strengths that affect the distribution of the methylation products and their selectivities. Also, specific surface area and porosity for some solid catalysts such as zeolites play additional roles in the overall reaction. Not only these properties of a catalyst that influence the methylation outcome but also the temperature, space velocity (WHSV, LHSV, GSHV), weight of catalyst per reactant flow rate (W/F), time of stream (TOS), and methanol/substrate molar ratio. The treated substrates herein discussed were aromatic hydrocarbons (benzene, biphenyls, naphthalenes, toluene, xylenes), alkenes, phenolics (phenol, cresols, anisole), N-heteroarenes, carbonyls, alcohols, and nitriles. Methylation of benzene affords not only toluene as main product but also polymethylated benzenes (xylenes, pseudocumene, hexamethylenebenzene, and also ethylbenzene as a sidechain product). Also, toluene is sensitive to the reaction conditions, giving rising to ring methylation and to sidechain one (ethylbenzene and styrene), besides the formation of benzene as a disproportionation product. Wealth of results from the methylation of phenolic compounds bears witness to the interest of different investigators in this special research. As to these phenolics, concurrent O-methylation inevitably parallels the C-methylation, and the selectivity of the latter one remains depended on the above-cited factors; ortho-cresol and 2,6-xylenol have been the main C-ring methylated phenols. Methylation of olefins with methanol over solid catalysts, leading to higher olefins, is of a great interest. The chemistry involved in the methylation of N-heteroarenes such as pyridines, indoles, and pyrroles is significant. Application of the methylation protocols, using methanol as a reagent and transition metal complexes as catalysts, to ketones, esters, aldehydes, nitriles, and alcohols, ends up with some important molecules such as acrylonitrile (a monomer) and isobutanol (a biofuel).

C-methylation of organic substrates: A comprehensive overview. Part iiia. Methanol as a methylating agent. A case of catalysis versatility

2021 ◽  
Vol 18 ◽  
Author(s):  
Saad Moulay
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Molecular Sieves ◽  
Acid Sites ◽  
Lewis Base ◽  
Side Chain ◽  
Organic Substrates ◽  
Solid Catalysts ◽  
The Impact

: The present account surveys the results of the myriad of works on the C-methylation of organic substrates with methanol as an eco-friendly methylating agent. The innumerable reports on this issue reveal the widespread use of a set of solid catalysts such as molecular sieves, zeolites, metal phosphates, metal oxides and transition metal complexes to accomplish such methylation. One related facet was the impact of the numbers of Brønstëd acid sites, Lewis acid sites, and Lewis base sites present in solid catalysts, such as zeolites, ratios, and strengths that affect the distribution of the methylation products and their selectivities. Moreover, specific surface area and porosity for some solid catalysts, such as zeolites, play additional roles in the overall reaction. Not only do these catalyst properties influence the methylation outcome, but the temperature, space velocity (WHSV, LHSV, GSHV), weight of catalyst per reactant flow rate (W/F), time of stream (TOS), and methanol/substrate molar ratio also do. The treated substrates herein discussed were aromatic hydrocarbons (benzene, biphenyls, naphthalenes, toluene, xylenes), alkenes, phenolics (phenol, cresols, anisole), N-heteroarenes, carbonyls, alcohols, and nitriles. Methylation of benzene affords not only toluene as the main product but also polymethylated benzenes (xylenes, pseudocumene, hexamethylenebenzene, and also ethylbenzene as a side-chain product). Furthermore, toluene is sensitive to the reaction conditions, giving rise to ring methylation and side-chain one (ethylbenzene and styrene), besides the formation of benzene as a disproportionation product. A number of results from the methylation of phenolic compounds bear witness to the interest of different investigators in this special research. As to these phenolics, concurrent O-methylation inevitably parallels the C-methylation, and the selectivity of the latter one remains dependent on the above-cited factors; ortho-cresol and 2,6-xylenol have been the main C-ring methylated phenols. Methylation of olefins with methanol over solid catalysts, leading to higher olefins, is of great interest. The chemistry involved in the methylation of N-heteroarenes, such as pyridines, indoles, and pyrroles, is significant. Application of the methylation protocols, using methanol as a reagent and transition metal complexes as catalysts to ketones, esters, aldehydes, nitriles, and alcohols, ends up with some important molecules such as acrylonitrile (a monomer) and isobutanol (a biofuel).

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