Journal Description
Reactions
Reactions
is an international, peer-reviewed, open access journal on reaction chemistry and engineering published quarterly online by MDPI.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within ESCI (Web of Science), Scopus, EBSCO, and other databases.
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 25.3 days after submission; acceptance to publication is undertaken in 4.8 days (median values for papers published in this journal in the first half of 2024).
- Recognition of Reviewers: APC discount vouchers, optional signed peer review, and reviewer names published annually in the journal.
Impact Factor:
2.2 (2023);
5-Year Impact Factor:
2.1 (2023)
Latest Articles
Carbon Nanotubes: A Review of Synthesis Methods and Applications
Reactions 2024, 5(3), 429-451; https://doi.org/10.3390/reactions5030022 - 4 Jul 2024
Abstract
Carbon nanotubes (CNTs) are cylindrical-shaped materials composed of hexagonally arranged hybridized carbon atoms with versatility in synthesis methods and diverse applications. This review is focused on the fabrication, physicochemical and spectroscopic characterization, and industrial applications of CNTs. This review discusses some promising synthesis
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Carbon nanotubes (CNTs) are cylindrical-shaped materials composed of hexagonally arranged hybridized carbon atoms with versatility in synthesis methods and diverse applications. This review is focused on the fabrication, physicochemical and spectroscopic characterization, and industrial applications of CNTs. This review discusses some promising synthesis methods for the preparation of CNTs such as catalytic chemical vapor deposition, arc discharge, and laser ablation. A comparative discussion is made between these synthesis methods in terms of strengths, opportunities and challenges. Furthermore, functionalization and purification of CNTs’ surface leading to improved functionality has also been highlighted in this article. Finally, the analytical techniques employed to shed light on the physicochemical and morphological properties of CNTs are described.
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(This article belongs to the Special Issue Nanoparticles: Synthesis, Properties, and Applications)
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Open AccessArticle
Investigation of the First Hydrogenation of LaNi5
by
Salma Sleiman, Samaneh Shahgaldi and Jacques Huot
Reactions 2024, 5(3), 419-428; https://doi.org/10.3390/reactions5030021 - 2 Jul 2024
Abstract
The first hydrogenation of most metal hydrides is a lengthy process that usually requires high pressure and temperature. This, in turn, significantly increases the production cost of metal hydrides. In this paper, the low temperature hydride-forming LaNi5 was selected to investigate the mechanism
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The first hydrogenation of most metal hydrides is a lengthy process that usually requires high pressure and temperature. This, in turn, significantly increases the production cost of metal hydrides. In this paper, the low temperature hydride-forming LaNi5 was selected to investigate the mechanism of first hydrogenation. For the first time, the effect of particle size, temperature and pressure on the incubation time were studied. We found that the first hydrogenation of LaNi5 follows an Arrhenius process, with an activation energy of EA = 78 ± 4 kJ/mol H2. We also found that the pre-exponential factor depends on the applied pressure.
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(This article belongs to the Special Issue Hydrogen Production and Storage, 2nd Edition)
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Open AccessArticle
The Effect of Temperature and Treatment Regime on the Physical, Chemical, and Biological Properties of Poultry Litter Biochar
by
Joyce Clarke and Maria Olea
Reactions 2024, 5(3), 379-418; https://doi.org/10.3390/reactions5030020 - 25 Jun 2024
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Poultry litter was converted to biochar by torrefaction and to hydrochar by hydrothermal carbonisation. Many parameters were measured for the resulting chars, to investigate the effects of the production method and production temperature. SEM showed the presence of large quantities of crystalline material
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Poultry litter was converted to biochar by torrefaction and to hydrochar by hydrothermal carbonisation. Many parameters were measured for the resulting chars, to investigate the effects of the production method and production temperature. SEM showed the presence of large quantities of crystalline material on the surface of the biochars. The elemental composition of some crystals was determined as 35% K and 31% Cl. This was confirmed as sylvite (KCl) crystals, which explains the high levels of water-extractable potassium in the biochar and may also be important in germination inhibition. Biochars almost totally inhibited germination, whilst hydrochars decreased germination. Although germination occurred on hydrochar, root growth was severely inhibited. Consequently, the germination index may be better to determine total phytotoxicity as it measures both effects and could be used as a bioassay for chars used as soil amendments. Washing removed germination inhibition in a low-temperature char (350 °C), possibly by removing KCl; however, root toxicity remained. There were very low levels of heavy metals, suggesting they are not the source of toxicity. In biochars, pore mean size decreased with temperature from 350 °C to 600 °C, due to changes in pore size distribution. The mean pore size was measured directly using SEM. The merits of this method are discussed. Low-temperature biochars seem best suited for fuel as they have a high calorific value, high hydrophobicity, a low ash content and a high yield. Higher temperatures are better for soil amendment and sequestration applications with a smaller mean pore size, higher surface area, and higher pH.
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Open AccessReview
Furfural and Levulinic Acid: Synthesis of Platform Molecules from Keggin Heteropolyacid-Catalyzed Biomass Conversion Reactions
by
Marcio Jose da Silva, Alana Alves Rodrigues and Daniel Carreira Batalha
Reactions 2024, 5(2), 361-378; https://doi.org/10.3390/reactions5020019 - 9 Jun 2024
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Among the different polyoxometalate compounds, Keggin heteropolyacids have been extensively used as catalysts in several acid-catalyzed reactions, due to their strong strength of Bronsted acidity. These metal–oxygen clusters have a highly versatile structure that allows their conversion to derivatives, which are catalysts that
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Among the different polyoxometalate compounds, Keggin heteropolyacids have been extensively used as catalysts in several acid-catalyzed reactions, due to their strong strength of Bronsted acidity. These metal–oxygen clusters have a highly versatile structure that allows their conversion to derivatives, which are catalysts that are much more efficient than their precursors, with a greater catalytic activity in a plethora of reactions of industrial interest. Particularly, due to the inevitable exhaustion of fossil sources, reactions to valorize biomass have attracted significant attention, since it is a precious renewable raw material that can provide fine chemicals or fuels, minimizing our dependence on petroproducts. Biorefinery processes can produce platform molecules to achieve this goal. In this review, the recent advances achieved in the development of routes to converting biomass feedstocks to levulinic acid and furfural, which are valuable ingredients in biorefinery processes, using Keggin heteropolyacid catalysts were assessed.
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Open AccessArticle
Advanced Thermogravimetric Analyses of Stem Wood and Straw Devolatilization: Torrefaction through Combustion
by
David R. Wagner
Reactions 2024, 5(2), 350-360; https://doi.org/10.3390/reactions5020018 - 7 Jun 2024
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Process design critically depends on the characterization of fuels and their kinetics under process conditions. This study steps beyond the fundamental methods of thermogravimetry to modulated (MTGA) and Hi-Res™ (high resolution) techniques to (1) add characterization detail and (2) increase the utility of
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Process design critically depends on the characterization of fuels and their kinetics under process conditions. This study steps beyond the fundamental methods of thermogravimetry to modulated (MTGA) and Hi-Res™ (high resolution) techniques to (1) add characterization detail and (2) increase the utility of thermal analysis data. Modulated TGA methods overlay sinusoidal functions on the heating rates to determine activation energy as a function of temperature with time. Under devolatilization conditions, Hi-Res™ TGA maintains a constant mass loss with time and temperature. These two methods, run independently or overlaid, offer additional analysis in which multiple samples at different heating rates are run to different final temperatures. Advanced methods allow researchers to use fewer samples by conducting fewer runs, targeting practical experimental designs, and quantifying errors easier. The parameters of the studies included here vary the heating rate at 10, 30, and 50 °C/min; vary gas-phase oxygen for pyrolysis or combustion conditions; and particle size ranges of 100–125 µm, 400–425 µm, and 600–630 µm. The two biomass fuels used in the studies are pinewood from Northern Sweden and wheat straw. The influence of torrefaction is also included at temperatures of 220, 250, and 280 °C. Apparent activation energy results align with the previous MTGA data in that combustion conditions yield higher values than pyrolysis conditions—200–250 kJ/mol and 175–225 kJ/mol for pine and wheat combustion, respectively, depending on pre-treatment. Results show the dependence of these parameters upon one another from a traditional thermal analysis approach, e.g., the Ozawa-Flynn-Wall method, as well as MTGA and Hi-Res™ thermogravimetric investigations to show future directions for thermal analysis techniques.
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Open AccessArticle
Modeling of the Anaerobic Digestion of Biomass Produced by Agricultural Residues in Greece
by
Efstathios Papachristopoulos, George N. Prodromidis, Dennis E. Mytakis, Vagelis G. Papadakis and Frank A. Coutelieris
Reactions 2024, 5(2), 338-349; https://doi.org/10.3390/reactions5020017 - 22 May 2024
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This study combines theoretical modeling and experimental validation to explore anaerobic digestion comprehensively. Developing a computational model is crucial for accurately simulating a digester’s performance, considering various feedstocks and operational parameters. The main objective was to adapt the anaerobic digestion model 1 (ADM1)
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This study combines theoretical modeling and experimental validation to explore anaerobic digestion comprehensively. Developing a computational model is crucial for accurately simulating a digester’s performance, considering various feedstocks and operational parameters. The main objective was to adapt the anaerobic digestion model 1 (ADM1) simulation code to align with the laboratory-scale anaerobic digestion reactor’s specifications, especially regarding the liquid–gas transfer process. Within this computational framework, users may define model parameters and elucidate processes occurring in compartments reflecting the physical design. The model accurately predicts total concentrations of chemical oxygen demand (COD) as well as the produced biogas, with an average difference of less than 10% between experimental and simulated data. This consistency underscores the reliability and effectiveness of the adapted model in capturing anaerobic digestion nuances under specified conditions.
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Open AccessReview
Ir-Catalyzed ortho-C-H Borylation of Aromatic C(sp2)-H Bonds of Carbocyclic Compounds Assisted by N-Bearing Directing Groups
by
Hamad H. Al Mamari
Reactions 2024, 5(2), 318-337; https://doi.org/10.3390/reactions5020016 - 1 May 2024
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C-H borylation is a powerful strategy for the construction of C-B bonds due to the synthetic versatility of C-B bonds. Various transition metals affect the powerful functionalization of C-H bonds, of which Ir is the most common. Substrate-directed methods have enabled directed Ir-catalyzed
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C-H borylation is a powerful strategy for the construction of C-B bonds due to the synthetic versatility of C-B bonds. Various transition metals affect the powerful functionalization of C-H bonds, of which Ir is the most common. Substrate-directed methods have enabled directed Ir-catalyzed C-H borylation at the ortho position. Amongst the powerful directing groups in Ir-catalyzed C-H borylation are N-containing carbocyclic systems. This review covers substrate-directed Ir-catalyzed ortho-C-H borylation of aromatic C(sp2)-H bonds in N-containing carbocyclic compounds, such as anilines, amides, benzyl amines, hydrazones, and triazines.
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Open AccessArticle
Generalized Linear Driving Force Formulas for Diffusion and Reaction in Porous Catalysts
by
Mirosław K. Szukiewicz and Elżbieta Chmiel-Szukiewicz
Reactions 2024, 5(2), 305-317; https://doi.org/10.3390/reactions5020015 - 29 Apr 2024
Abstract
Approximate models are a fast and most often precise tool for determining the effectiveness factor for heterogeneous catalysis processes that are realized in the real world. They are also frequently applied as robust transient models describing the work of a single catalyst pellet
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Approximate models are a fast and most often precise tool for determining the effectiveness factor for heterogeneous catalysis processes that are realized in the real world. They are also frequently applied as robust transient models describing the work of a single catalyst pellet or as a part of a more complex model, for example, a reactor model, where mass balances for the gas phase and solid phase are necessary. So far, approximate models for diffusion and reaction processes have been presented for processes described by a single balance equation. In the present work, approximate models without the mentioned limitation are presented and discussed. In addition, simple rules are shown for the development of other complex approximate models without tedious derivation in the complex domain. The formulas considered in this work are typical long-time approximations of the transient process. The accuracy is good, especially in the range of small and intermediate Thiele modulus values.
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(This article belongs to the Special Issue Feature Papers in Reactions in 2024)
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Sewage Sludge Plasma Gasification: Characterization and Experimental Rig Design
by
Nuno Pacheco, André Ribeiro, Filinto Oliveira, Filipe Pereira, L. Marques, José C. Teixeira, Cândida Vilarinho and Flavia V. Barbosa
Reactions 2024, 5(2), 285-304; https://doi.org/10.3390/reactions5020014 - 16 Apr 2024
Abstract
The treatment of wastewater worldwide generates substantial quantities of sewage sludge (SS), prompting concerns about its environmental impact. Various approaches have been explored for SS reuse, with energy production emerging as a viable solution. This study focuses on harnessing energy from domestic wastewater
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The treatment of wastewater worldwide generates substantial quantities of sewage sludge (SS), prompting concerns about its environmental impact. Various approaches have been explored for SS reuse, with energy production emerging as a viable solution. This study focuses on harnessing energy from domestic wastewater treatment (WWT) sewage sludge through plasma gasification. Effective syngas production hinges on precise equipment design which, in turn, depends on the detailed feedstock used for characterization. Key components of plasma gasification include the plasma torch, reactor, heat exchanger, scrubber, and cyclone, enabling the generation of inert slag for landfill disposal and to ensure clean syngas. Designing these components entails considerations of sludge composition, calorific power, thermal conductivity, ash diameter, and fusibility properties, among other parameters. Accordingly, this work entails the development of an experimental setup for the plasma gasification of sewage sludge, taking into account a comprehensive sludge characterization. The experimental findings reveal that domestic WWT sewage sludge with 40% humidity exhibits a low thermal conductivity of approximately 0.392 W/mK and a calorific value of LHV = 20.78 MJ/kg. Also, the relatively low ash content (17%) renders this raw material advantageous for plasma gasification processes. The integration of a detailed sludge characterization into the equipment design lays the foundation for efficient syngas production. This study aims to contribute to advancing sustainable waste-to-energy technologies, namely plasma gasification, by leveraging sewage sludge as a valuable resource for syngas production.
Full article
(This article belongs to the Special Issue Waste Biorefinery Technologies for Accelerating Sustainable Energy Processes)
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Biosynthesis of Copper Nanoparticles from Acacia cornigera and Annona purpurea and Their Insecticidal Effect against Tribolium castaneum
by
Rogelio Solorzano Toala, Federico Gutierrez-Miceli, Benjamin Valdez-Salas, Ernesto Beltran-Partida, Daniel Gonzalez-Mendoza, Olivia Tzintzun-Camacho, Onecimo Grimaldo-Juarez and Antobelli Basilio-Cortes
Reactions 2024, 5(2), 274-284; https://doi.org/10.3390/reactions5020013 - 8 Apr 2024
Abstract
Diverse studies have showed that the pesticides can cause important damages in ecosystem. Therefore, the development of bio pesticides through nanotechnology can increase efficacy and limit the negative impacts in the environmental that traditionally seen through the use of chemical pesticides. Nanoparticles obtained
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Diverse studies have showed that the pesticides can cause important damages in ecosystem. Therefore, the development of bio pesticides through nanotechnology can increase efficacy and limit the negative impacts in the environmental that traditionally seen through the use of chemical pesticides. Nanoparticles obtained from plants’ extracts can be used for effective pest management as a combined formulation of metal and some other organic material present in the plants. In the present study, our evaluated biosynthesis of nanoparticles of copper used two plant extracts (Acacia cornigera and Annona purpurea), and the Taguchi method was adopted for the synthesis optimization of the following variables of biosynthesis: temperature, pH, extract concentration, and reaction times to maximize the insecticidal activity on Tribolium castaneum. Our results showed that the nanoparticles were successfully synthesized using Acacia cornigera and Anona purpurea extract under optimum conditions under Taguchi L 9 orthogonal design, where copper nanoparticles were obtained with a size of 63–153 nm for using A. cornigera extract, 87–193 nm for A. purpurea extract, and a zeta potential of 9.6 mV and −32.7 mV, respectively. The nanoparticles of copper from A. cornigera showed effective insecticidal activity against Tribolium castaneum, and 90% mortality compared to the 76.6% obtained from nanoparticles of copper from A. purpurea. The results suggest that Cu-nanoparticles derived from both plants could be used as a biocontrol agent of Tribolium castaneum, a pest of stored grain with great economic importance.
Full article
(This article belongs to the Special Issue Nanoparticles: Synthesis, Properties, and Applications)
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Valorization of (Bio)Ethanol over MoO3/(WO3-ZrO2) Sol-Gel-like Catalysts
by
Ana Paula Soares Dias, Bruna Rijo, Manuel Francisco Costa Pereira, Rodica Zăvoianu and Octavian Dumitru Pavel
Reactions 2024, 5(1), 260-273; https://doi.org/10.3390/reactions5010012 - 20 Mar 2024
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Bioethanol, which is currently produced commercially from a growing variety of renewable biomass and waste sources, is an appealing feedstock for the production of fuels and chemicals. The literature clearly shows that bioethanol is a versatile building block to be used in biorefineries.
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Bioethanol, which is currently produced commercially from a growing variety of renewable biomass and waste sources, is an appealing feedstock for the production of fuels and chemicals. The literature clearly shows that bioethanol is a versatile building block to be used in biorefineries. The ethanol conversion using several catalysts with acidic, basic, and redox characteristics results in a diverse assortment of high-value bioproducts. High-acidity tungsten zirconia-based catalysts are stated to compete with traditional zeolitic catalysts and can be employed in the dehydration of ethanol to ethylene, but for a low reaction temperature acetic acid is formed, which causes corrosion issues. WO3-ZrO2 (W/Zr = 1, atomic) catalysts modified with MoO3 were prepared by a sol-gel-like procedure and tested in a gas phase ethanol conversion in the presence of air. The citrate derived xerogels were annealed at 853 K for 12 h, allowing low surface area (<10 m2/g) materials with a Mo-W mixed-oxide-rich surface over tetragonal nanostructured zirconia. Catalysts with MoO3-loading produced mainly acetaldehyde, instead of ethylene, as a result of the high reducibility of Mo6+ when compared to W6+. During the reaction, the Mo6+ becomes partially reduced, but Mo6+/Mo5+ species are still active for methanol conversion with increased ethylene selectivity due to the high acidity of tetrahedral MOX species formed during the reaction. Adding water to ethanol, to simulate bioethanol, only leads to a slight inhibition in ethanol conversion over the MoO3/(WO3-ZrO2) catalysts. The results show that molybdenum oxide deposited on tungstated zirconia catalyst is active, with low sensitivity to water, for the valorization of bioethanol into high-value chemicals, such as ethylene and acetaldehyde, and whose selectivity can be tuned by changing the amount of MoO3 that is loaded. The MoO3/(WO3-ZrO2) catalysts prepared show catalytic behavior similar to that of noble metal-based catalysts reported in the literature for the dehydrogenation of bioethanol in high-value chemicals.
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Open AccessArticle
Analytical and Numerical Thermodynamic Equilibrium Simulations of Steam Methane Reforming: A Comparison Study
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Bruno Varandas, Miguel Oliveira and Amadeu Borges
Reactions 2024, 5(1), 246-259; https://doi.org/10.3390/reactions5010011 - 8 Mar 2024
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Computer simulation is a crucial element in the design of chemical processes. Although numerous commercial software options are widely recognized, the expense associated with acquiring and sustaining valid software licenses can be prohibitive. In contrast, open-source software, being freely available, provides an opportunity
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Computer simulation is a crucial element in the design of chemical processes. Although numerous commercial software options are widely recognized, the expense associated with acquiring and sustaining valid software licenses can be prohibitive. In contrast, open-source software, being freely available, provides an opportunity for individuals to study, review, and modify simulation models. This accessibility fosters technology transfer and facilitates knowledge dissemination, benefiting both academic and industrial domains. In this study, a thermodynamic equilibrium steady-state analysis of steam methane reforming using a natural-gas-like intake fuel was conducted. An analytical method was developed on the Microsoft Excel platform, utilizing the material balance equations system. The obtained results were compared to numerical methods employing the free-of-charge chemical process simulation software COCO and DWSIM. The investigation explored the influence of temperature, pressure, and steam-to-carbon ratio to determine optimal operating conditions. The findings suggest that higher temperatures and lower pressures are highly favorable for this process, considering that the choice of steam-to-carbon ratio depends on the desired conversion, with a potential disadvantage of coke formation at lower values. Consistent results were obtained through both analytical and numerical methods. Notably, simulations performed using DWSIM showed a deviation of 6.42% on average compared to COCO values. However, it was observed that the analytical method tended to overestimate the results by an average of 3.01% when compared to the simulated results from COCO, highlighting the limitations of this analytical approach.
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Open AccessReview
Bioorthogonal “Click” Cycloadditions: A Toolkit for Modulating Polymers and Nanostructures in Living Systems
by
Irene Lepori, Yavuz Oz, Jungkyun Im, Nandan Ghosh, Mohuya Paul, Ulrich S. Schubert and Stefano Fedeli
Reactions 2024, 5(1), 231-245; https://doi.org/10.3390/reactions5010010 - 4 Mar 2024
Abstract
“Click” cycloadditions offer effective pathways for the modifications of supramolecular structures, polymers, and nanomaterials. These reactions include bioorthogonal mechanisms that do not interfere with the biological processes, providing a type of chemistry to operate directly in living environments, such as cells and animals.
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“Click” cycloadditions offer effective pathways for the modifications of supramolecular structures, polymers, and nanomaterials. These reactions include bioorthogonal mechanisms that do not interfere with the biological processes, providing a type of chemistry to operate directly in living environments, such as cells and animals. As a result, the “click” cycloadditions represent highly and selective tools for tailoring the properties of nanomedicine scaffolds, expanding the efficacy of multiple therapeutic strategies. We focused this minireview on the bioorthogonal cycloadditions, presenting an insight into the strategies to modify nanostructured biomedical scaffolds inside living systems. We organized the contributions according to the three main mechanisms of “click” cycloadditions: strain-promoted sydnone-alkyne, tetrazine ligation, and strain-promoted [3+2] azido-alkyne.
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(This article belongs to the Special Issue Cycloaddition Reactions at the Beginning of the Third Millennium)
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Open AccessArticle
Reduction and Cycloaddition of Heteroalkenes at Ga(I) Bisamide Center
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Vladimir A. Dodonov, Olga A. Kushnerova, Evgeny V. Baranov and Igor L. Fedushkin
Reactions 2024, 5(1), 213-230; https://doi.org/10.3390/reactions5010009 - 20 Feb 2024
Abstract
The reactivity of the complex [(dpp-bian)GaNa(DME)2] (1) (dpp-bian = 1,2-bis[(2,6-di-isopropylphenyl)imino]acenaphthene) towards isocyanates, benzophenone, diphenylketene, and 1,2-dibenzylidenehydrazine has been studied. Treatment of 1 with isocyanates led to derivatives of imidoformamide [(dpp-bian)Ga{C(=NPh)2}2–NPh][Na(DME)3] (2),
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The reactivity of the complex [(dpp-bian)GaNa(DME)2] (1) (dpp-bian = 1,2-bis[(2,6-di-isopropylphenyl)imino]acenaphthene) towards isocyanates, benzophenone, diphenylketene, and 1,2-dibenzylidenehydrazine has been studied. Treatment of 1 with isocyanates led to derivatives of imidoformamide [(dpp-bian)Ga{C(=NPh)2}2–NPh][Na(DME)3] (2), biuret [(dpp-bian)Ga(NCy)2(CO)2NCy][Na(DME)] (3), or carbamic acids [(dpp-bian)GaN(Cy)C(O)O]2[Na(THF)(Et2O)] (4), [(dpp-bian)GaC(=NCy)N(Cy)C(O)O][Na(Py)3] (5). Treatment of 1 with 2 equiv. of Ph2CO resulted in gallium pinacolate [(dpp-bian)GaO(CPh2)2O][Na(Py)2] (9), while the reaction of 1 with 2 equiv. Ph2CCO gave divinyl ether derivative [(dpp-bian)Ga{C(=CPh2)O}2][Na(DME)3] (10). Complex 1 treated with 2 equiv. 1,2-dibenzylidenehydrazine underwent [1+2+2] cycloaddition to give C–C coupling product [(dpp-bian)Ga{N(NCHPh)}2(CHPh)2][Na(DME)3] (11). When complex 1 was sequentially treated with 1 equiv. of 1,2-dibenzylidenehydrazine and 1 equiv. of pyridine or pyridine-d5; it gave [1+2+2] cycloaddition product [(dpp-bian)GaN(NCHPh)C(Ph)CN][Na(DME)3] (12). Compounds 2–12 were characterized by NMR and IR spectroscopy, and their molecular structures were established by single-crystal X-ray diffraction analysis.
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(This article belongs to the Special Issue Cycloaddition Reactions at the Beginning of the Third Millennium)
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Open AccessReview
Use of Biosourced Molecules as Liquid Organic Hydrogen Carriers (LOHC) and for Circular Storage
by
Nelson Alexis Bermudez Aponte and Valérie Meille
Reactions 2024, 5(1), 195-212; https://doi.org/10.3390/reactions5010008 - 7 Feb 2024
Cited by 1
Abstract
The use of Liquid Organic Hydrogen Carriers (LOHC) is one of the potential options to store hydrogen. Today, the vast majority of compounds used as LOHC come from the oil industry. Using biosourced LOHC would be a step forward in the development of
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The use of Liquid Organic Hydrogen Carriers (LOHC) is one of the potential options to store hydrogen. Today, the vast majority of compounds used as LOHC come from the oil industry. Using biosourced LOHC would be a step forward in the development of this CO2-free solution. This article looks at LOHC candidates that can be obtained from biomass. The special case of formic acid and methanol, which do not fall within the definition of LOHC, is also considered. The synthesis of alcohols, polyols, amines, aminoalcohols and N-heterocyclic compounds from biosourced compounds is reviewed.
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(This article belongs to the Special Issue Hydrogen Production and Storage, 2nd Edition)
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Open AccessReview
Photocatalytic TiO2-Based Nanostructures as a Promising Material for Diverse Environmental Applications: A Review
by
Maria-Anna Gatou, Athanasia Syrrakou, Nefeli Lagopati and Evangelia A. Pavlatou
Reactions 2024, 5(1), 135-194; https://doi.org/10.3390/reactions5010007 - 1 Feb 2024
Cited by 4
Abstract
Contemporary technological and industrial advancements have led to increased reliance on chemicals for product innovation, leading to heightened contamination of water sources by traditional pollutants (organic dyes, heavy metals) and disease-causing microorganisms. Wastewater treatment processes now reveal “emerging pollutants”, including pharmaceuticals, endocrine disruptors,
[...] Read more.
Contemporary technological and industrial advancements have led to increased reliance on chemicals for product innovation, leading to heightened contamination of water sources by traditional pollutants (organic dyes, heavy metals) and disease-causing microorganisms. Wastewater treatment processes now reveal “emerging pollutants”, including pharmaceuticals, endocrine disruptors, and agricultural chemicals. While some are benign, certain emerging pollutants can harm diverse organisms. Researchers seek cost-effective water purification methods that completely degrade pollutants without generating harmful by-products. Semiconductor-based photocatalytic degradation, particularly using titanium dioxide (TiO2), is popular for addressing water pollution. This study focuses on recent applications of TiO2 nanostructures in photocatalysis for eliminating various water pollutants. Structural modifications, like doping and nanocomposite formation, enhance photocatalyst performance. The study emphasizes photocatalytic elimination mechanisms and comprehensively discusses factors impacting both the mechanism and performance of nano-TiO2-based photocatalysts. Characteristics of TiO2, such as crystal structure and energy band-gap, along with its photocatalytic activity mechanism, are presented. The review covers the advantages and limitations of different TiO2 nanostructure production approaches and addresses potential toxicity to human health and the environment. In summary, this review provides a holistic perspective on applying nano-TiO2 materials to mitigate water pollution.
Full article
(This article belongs to the Special Issue Nanoparticles: Synthesis, Properties, and Applications)
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Open AccessArticle
Oxidative Cleavage of 9,10-Dihydroxystearic Acid on Supported Au, Pd and PdAu Nanoparticle-Based Catalysts
by
Dmitrii German, Vladislav Turyanskiy, Julia Schroeder, Mohammed Al-Yusufi, Katja Neubauer, Angela Köckritz, Sónia A. C. Carabineiro, Ekaterina Kolobova and Alexey Pestryakov
Reactions 2024, 5(1), 120-134; https://doi.org/10.3390/reactions5010006 - 27 Jan 2024
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The oxidative C-C cleavage of a C18 substrate is an important transformation in synthetic organic chemistry, facilitating the synthesis of valuable C8-C9 acids widely used in many industries. Through a comparative analysis of the catalytic and physicochemical properties of
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The oxidative C-C cleavage of a C18 substrate is an important transformation in synthetic organic chemistry, facilitating the synthesis of valuable C8-C9 acids widely used in many industries. Through a comparative analysis of the catalytic and physicochemical properties of catalysts, comprising mono- (Pd or Au) and bimetallic (PdAu) nanoparticles deposited on oxides, oxyhydroxides and graphite-like carbon material Sibunit (Cp), it was shown that the efficiency of the catalyst in the oxidative cleavage of 9,10-dihydroxystearic acid relies on the nature of the active component, the support and the average size of metal nanoparticles (NPs). The dependency of 9,10-DSA conversion on the average size of metal NPs shows the structural sensitivity of the oxidative cleavage reaction. Notably, catalysts with an average size of gold particles less than 3 nm exhibit the highest activity. The nature of the active component and the support material are crucial factors determining the process selectivity. Among the catalysts studied, the most effective for the oxidative cleavage of 9,10-DSA is a material based on Au NPs deposited on Cp.
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Open AccessBrief Report
Preparation of Dibenzofurotropones via Pd-Catalyzed Cyclization
by
Yu-Wei Lin and Shiuh-Tzung Liu
Reactions 2024, 5(1), 111-119; https://doi.org/10.3390/reactions5010005 - 22 Jan 2024
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A synthetic approach to dibenzofurotropone derivatives 1 has been developed through the palladium-catalyzed cyclization of (2-bromoaryl)(3-arylfuran-2-yl)methanones 2 via the activation of arylic C–H bonds. Compounds 2 were easily prepared from the palladium-promoted acyl migration and cyclization of (Z)-pent-2-en-4-yn-1-yl acetates 3 in
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A synthetic approach to dibenzofurotropone derivatives 1 has been developed through the palladium-catalyzed cyclization of (2-bromoaryl)(3-arylfuran-2-yl)methanones 2 via the activation of arylic C–H bonds. Compounds 2 were easily prepared from the palladium-promoted acyl migration and cyclization of (Z)-pent-2-en-4-yn-1-yl acetates 3 in the presence of 1,8-diazabicyclo(5.4.0)undec-7-ene (DBU), followed by oxidative decarbonylation and oxidation with O2. Ten new tropone compounds are reported and these compounds show absorption in the UV-vis region and emission in the visible region.
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Open AccessArticle
Formation of OH Radicals on BiVO4–TiO2 Nanocomposite Photocatalytic Film under Visible-Light Irradiation: Roles of Photocatalytic Reduction Channels
by
Shizu Terao and Yoshinori Murakami
Reactions 2024, 5(1), 98-110; https://doi.org/10.3390/reactions5010004 - 22 Jan 2024
Abstract
In this study, we investigated the effects of H2O2 addition on OH radical formation on the surfaces of visible-light-irradiated BiVO4–TiO2 nanocomposite photocatalysts. Additionally, we examined the possible roles of OH radicals formed by the reduction reaction of
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In this study, we investigated the effects of H2O2 addition on OH radical formation on the surfaces of visible-light-irradiated BiVO4–TiO2 nanocomposite photocatalysts. Additionally, we examined the possible roles of OH radicals formed by the reduction reaction of H2O2 on the visible-light-irradiated surfaces of photocatalytic BiVO4–TiO2 nanocomposites. The BiVO4–TiO2 nanocomposite photocatalysts were prepared by mixing a BiVO4 photocatalytic film with commercially available semiconductor particulate TiO2 photocatalysts. By removing oxygen gas from the photocatalytic reactor, the effects of oxygen molecules on OH radical formation during the visible-light irradiation of BiVO4–TiO2 nanocomposite photocatalysts were examined. During visible-light irradiation, BiVO4 and BiVO4–TiO2 photocatalysts play different roles in OH radical formation because of two characteristic reduction reaction channels: (a) the direct reduction of H2O2 on photocatalytic surfaces and (b) the indirect reduction reaction of H2O2 by superoxide radical anions (O2−).
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(This article belongs to the Special Issue Feature Papers in Reactions in 2023)
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Open AccessArticle
Dry and Hydrothermal Co-Carbonization of Mixed Refuse-Derived Fuel (RDF) for Solid Fuel Production
by
Andrei Longo, Octávio Alves, Ali Umut Sen, Catarina Nobre, Paulo Brito and Margarida Gonçalves
Reactions 2024, 5(1), 77-97; https://doi.org/10.3390/reactions5010003 - 16 Jan 2024
Abstract
The present study aims to test several conditions of the thermochemical pretreatment of torrefaction and carbonization to improve the physical and combustible properties of the Portuguese RDF. Therefore, two different types of RDF were submitted alone or mixed in 25%, 50%, and 75%
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The present study aims to test several conditions of the thermochemical pretreatment of torrefaction and carbonization to improve the physical and combustible properties of the Portuguese RDF. Therefore, two different types of RDF were submitted alone or mixed in 25%, 50%, and 75% proportions to dry carbonization processes in a range of temperatures between 250 to 350 °C and residence time between 15 and 60 min. Hydrothermal carbonization was also carried out with RDF samples and their 50% mixture at temperatures of 250 and 300 °C for 30 min. The properties of the 51 chars and hydrochars produced were analyzed. Mass yield, apparent density, proximate and elemental analysis, ash mineral composition, and higher heating value (HHV), among others, were determined to evaluate the combustion behavior improvement of the chars. The results show that after carbonization, the homogeneity and apparent density of the chars were increased compared to the raw RDF wastes. The chars and hydrochars produced present higher HHV and lower moisture and chlorine content. In the case of chars, a washing step seems to be essential to reduce the chlorine content to allow them to be used as an alternative fuel. In conclusion, both dry and wet carbonization demonstrated to be important pretreatments of the RDF to produce chars with improved physical and combustion properties.
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(This article belongs to the Special Issue Waste Biorefinery Technologies for Accelerating Sustainable Energy Processes)
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