Editorial

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3 pages, 175 KiB

Open AccessEditorial

The Role of Catalysts in Functionalization of C-H and C-C Bonds

by Mohamed Mokhtar M. Mostafa, Tamer Said S. Saleh and Nerseen Said I. Ahmed

Catalysts 2023, 13(2), 377; https://doi.org/10.3390/catal13020377 - 09 Feb 2023

Viewed by 1233

Abstract

Catalysis is one of the fundamental pillars of green chemistry [...] Full article

(This article belongs to the Special Issue The Role of Catalysts in Functionalization of C-H and C-C Bonds)

Research

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19 pages, 6549 KiB

Open AccessArticle

Synthesis and Characterization of Terbium-Based Metal Organic Framework for Environmental Remediation Application

by Asma D. Alomari, Dalal Alezi and Mohamed Abdel Salam

Catalysts 2023, 13(2), 241; https://doi.org/10.3390/catal13020241 - 20 Jan 2023

Cited by 2 | Viewed by 1453

Abstract

In the present study, terbium-based metal-organic frameworks (MOFs) based on fcu topology, fcu-Tb- FTZB-MOF, was synthesized using 2-fluoro-4-(1H-tetrazol-5-yl)benzoic acid (FTZB) as a linear ligand, and then was characterized using powder X-ray diffraction (PXRD) and Brunauer-Emmett-Teller (BET) analysis and to study the texture properties [...] Read more.

In the present study, terbium-based metal-organic frameworks (MOFs) based on fcu topology, fcu-Tb- FTZB-MOF, was synthesized using 2-fluoro-4-(1H-tetrazol-5-yl)benzoic acid (FTZB) as a linear ligand, and then was characterized using powder X-ray diffraction (PXRD) and Brunauer-Emmett-Teller (BET) analysis and to study the texture properties of the Tb-FTZB-MOF. The characterization results confirmed the successful synthesis of the high surface area Tb-FTZB-MOF (1220 m²/g). The synthesized Tb-FTZB-MOF was then applied as a catalytic adsorbent to remove direct violet 31 (DV31) dye as an example of organic pollutants, from a model and real solution. The effect of various operational parameters such as adsorbent loading, contact time, initial DV31 dye concentration, initial solution pH, different water matrix, temperature, and ionic strength have also been evaluated. Solution pH and temperature significantly influenced the adsorption of DV31 dye using Tb-FTZB-MOF, and the results should efficiently remove the DV31 dye at ambient temperature, and at pH value of 8.0 using 35 mg Tb-FTZB-MOF, within few minutes. The process was studied kinetically and found to follow the pseudo-second-order kinetic model, and thermodynamically the process was spontaneous, endothermic, with a positive entropy. Finally, the result showed that Tb-FTZB-MOF was able to adsorb a high percentage of DV31 dye and maintained reasonable efficiency even after five cycles, indicating that Tb-FTZB-MOF could be a promising adsorbent in wastewater remediation. Full article

(This article belongs to the Special Issue The Role of Catalysts in Functionalization of C-H and C-C Bonds)

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14 pages, 3240 KiB

Open AccessArticle

Revisiting the Semi-Hydrogenation of Phenylacetylene to Styrene over Palladium-Lead Alloyed Catalysts on Precipitated Calcium Carbonate Supports

by Yifan Zheng, Lin Gu, Yining Li, Jamal Ftouni and Abhishek Dutta Chowdhury

Catalysts 2023, 13(1), 50; https://doi.org/10.3390/catal13010050 - 27 Dec 2022

Cited by 2 | Viewed by 2131

Abstract

The quest for improved heterogeneous catalysts often leads to sophisticated solutions, which are expensive and tricky to scale up industrially. Herein, the effort to upgrade the existing inorganic nonmetallic materials has seldom been prioritized by the catalysis community, which could deliver cost-effective solutions [...] Read more.

The quest for improved heterogeneous catalysts often leads to sophisticated solutions, which are expensive and tricky to scale up industrially. Herein, the effort to upgrade the existing inorganic nonmetallic materials has seldom been prioritized by the catalysis community, which could deliver cost-effective solutions to upgrade the industrial catalysts catalog. With this philosophy in mind, we demonstrate in this work that alloyed palladium-lead (Pd-Pb) deposited on novel precipitated calcium carbonate (PCC) supports could be considered an upgraded version of the industrial Lindlar catalyst for the semi-hydrogenation of phenylacetylene to styrene. By utilizing PCC supports of variable surface areas (up to 60 m²/g) and alloyed Pd-Pb loading, supported by material characterization tools, we showcase that achieving the “active-site isolation” feature could be the most pivotal criterion to maximize semi-hydrogenated alkenes selectivity at the expense of prohibiting the complete hydrogenation to alkanes. The calcite phase of our PCC supports governs the ultimate catalysis, via complexation with uniformly distributed alloyed Pb, which may facilitate the desired “active-site isolation” feature to boost the selectivity to the preferential product. Through this work, we also advocate increasing research efforts on mineral-based inorganic nonmetallic materials to deliver novel and improved cost-effective catalytic systems. Full article

(This article belongs to the Special Issue The Role of Catalysts in Functionalization of C-H and C-C Bonds)

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18 pages, 5037 KiB

Open AccessArticle

Synthesis, Characterization and Dye Removal Capability of Conducting Polypyrrole/Mn_0.8Zn_0.2Fe₂O₄/Graphite Oxide Ternary Composites

by Mohamed A. Gabal, Enam A. Al-Harthy, Yasser M. Al Angari, Mohamed Abdel Salam, Ayman Awad, Amany A. Al-Juaid and Abdu Saeed

Catalysts 2022, 12(12), 1624; https://doi.org/10.3390/catal12121624 - 10 Dec 2022

Cited by 8 | Viewed by 1544

Abstract

Herein, ternary composites from polypyrrole (PPy), Mn_0.8Zn_0.2Fe₂O₄ (MZF), and graphite oxide (GO) were prepared to remove acid red dye (AR1) from wastewater. MZF was synthesized using spent Zn–C batteries, acid leaching, and sucrose auto-combustion processes; GO [...] Read more.

Herein, ternary composites from polypyrrole (PPy), Mn_0.8Zn_0.2Fe₂O₄ (MZF), and graphite oxide (GO) were prepared to remove acid red dye (AR1) from wastewater. MZF was synthesized using spent Zn–C batteries, acid leaching, and sucrose auto-combustion processes; GO was prepared via oxidation and exfoliation of graphite. The composites were prepared by adding MZF and GO during the in-situ polymerization of pyrrole. Different PPy/MZF/GO (PMG) composites were prepared by changing the weight ratios of the PPy, MZF, and GO. We investigated the prepared composites’ structural, magnetic, and electrical/dielectric properties. We evaluated different experimental conditions’ influences on dye removal performance, such as pH, dosage, dye concentration, temperature, and contact time. XRD, FT-IR, and magnetic properties indicated that PPy completely coated the other contents. The electrical/dielectric properties improved while increasing the GO ratio. The PMG at GO content 50 wt.% (PMG50) showed the most efficient ratio for better removing AR1 from wastewater. Full article

(This article belongs to the Special Issue The Role of Catalysts in Functionalization of C-H and C-C Bonds)

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13 pages, 4579 KiB

Open AccessArticle

Selective Oxidation of Alcohols and Alkenes with Molecular Oxygen Catalyzed by Highly Dispersed Cobalt (II) Decorated 12-Tungstosilicic Acid-Modified Zirconia

by Soyeb Pathan, Anjali Patel and Harshita Tilani

Catalysts 2022, 12(12), 1622; https://doi.org/10.3390/catal12121622 - 10 Dec 2022

Cited by 4 | Viewed by 1451

Abstract

Traditional procedures for oxidation processes suffer from a lack of selectivity, the use of organic solvents, the toxicity of the reagents, and waste production. As a cleaner alternative, highly dispersed Co over 12-tungstosilicicacid modified zirconia was synthesized and used for the selective oxidation [...] Read more.

Traditional procedures for oxidation processes suffer from a lack of selectivity, the use of organic solvents, the toxicity of the reagents, and waste production. As a cleaner alternative, highly dispersed Co over 12-tungstosilicicacid modified zirconia was synthesized and used for the selective oxidation of benzyl alcohol and styrene with molecular oxygen to carbonyl compounds under environmentally benign solvent-free conditions. The supremacy of the present catalyst lies in achieving excellent selectivity (>90%) for products with a very high turnover number. The catalytic activity of the recycled catalysts was also explored under optimized conditions to confirm sustainability. Further, the viability of the catalyst was studied via oxidation of various alcohols and alkenes under optimized conditions as well as superiority by comparison with the reported catalysts. Full article

(This article belongs to the Special Issue The Role of Catalysts in Functionalization of C-H and C-C Bonds)

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16 pages, 3718 KiB

Open AccessArticle

Sol-Gel Synthesis of ZnO Nanoparticles Using Different Chitosan Sources: Effects on Antibacterial Activity and Photocatalytic Degradation of AZO Dye

by Ilham Ben Amor, Hadia Hemmami, Salah Eddine Laouini, Mohammed Sadok Mahboub and Ahmed Barhoum

Catalysts 2022, 12(12), 1611; https://doi.org/10.3390/catal12121611 - 08 Dec 2022

Cited by 27 | Viewed by 2976

Abstract

Chitosan was used in the sol-gel synthesis of zinc oxide nanoparticles (ZnO NPs) as a capping agent in order to control the size, morphology, optical bandgap, photocatalytic efficiency, and antimicrobial activity. Different chitosan sources were used for the sol-gel synthesis of ZnO NPs, [...] Read more.

Chitosan was used in the sol-gel synthesis of zinc oxide nanoparticles (ZnO NPs) as a capping agent in order to control the size, morphology, optical bandgap, photocatalytic efficiency, and antimicrobial activity. Different chitosan sources were used for the sol-gel synthesis of ZnO NPs, namely chitosan of shrimp shells, crab shells, and Streptomyces griseus bacteria. The photocatalytic efficiency was studied by using the methylene blue (MB) photodegradation test, and the antibacterial activity of the different types of ZnO NPs was investigated by the agar well diffusion technique. The particle size of ZnO NPs varied between 20 and 80 nm, and the band gap energy ranged between 2.7 and 3.2 eV. Due to the different chitosan sources, the ZnO NPs showed different antibacterial activity against Listeria innocua, Bacillus Subtiliis, Staphylococcus Aureus, Salmonella Typhimurium and Pseudomonas Aeruginosa. The ZnO NPs with lower band gap values showed better antibacterial results compared to ZnO NPs with higher band gap values. The MB dye removal of ZnO (shrimp shells), ZnO (crab shells), and ZnO (Streptomyces griseus) reached 60%, 56%, and 44%, respectively, at a contact time of 60 min, a low initial MB dye concentration of 6 × 10⁻⁵ M, a solution temperature of 25 °C, and a pH = 7. Full article

(This article belongs to the Special Issue The Role of Catalysts in Functionalization of C-H and C-C Bonds)

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20 pages, 8065 KiB

Open AccessArticle

Production of Biofuel Additives Using Catalytic Bioglycerol Etherification: Kinetic Modelling and Reactive Distillation Design

by Abdulrahman A. Al-Rabiah, Rayan K. Al Darwish, Abdullah E. Alqahtani, Diego Morais Chaves and Márcio J. da Silva

Catalysts 2022, 12(11), 1332; https://doi.org/10.3390/catal12111332 - 01 Nov 2022

Cited by 3 | Viewed by 1954

Abstract

Glycerol is an unavoidable by-product of the biodiesel production process. The conversion of glycerol into valuable biofuel additives is essential in the fuel industry. The goal of this work is to develop a reactive distillation-based process for the production of biofuel additives by [...] Read more.

Glycerol is an unavoidable by-product of the biodiesel production process. The conversion of glycerol into valuable biofuel additives is essential in the fuel industry. The goal of this work is to develop a reactive distillation-based process for the production of biofuel additives by bio-glycerol etherification. In this study, a kinetic model using a lumping approach for glycerol etherification with tert-butyl alcohol (TBA) over Sn (II) phosphomolybdate (Sn_1.5PMo₁₂O₄₀) catalyst was developed. Aspen Plus was used to validate the kinetic model by simulating the glycerol etherification with TBA in a batch reactor. The model predictions were in good agreement with the experimental data. A reactive distillation-based process to produce glycerol ethers was developed, and heat integration was conducted to reduce energy consumption. The energy requirements of the integrated process and the CO₂ emissions were decreased by 17% and 14%, respectively. An economic evaluation was performed to study the profitability of the process for an annual capacity of 33,000 metric tons of glycerol ethers. It was found that the process is economically attractive, with a return on investment of 29.40% and a payback period of 2.2 years. The reactive distillation-based process is green and promising for producing biofuel additives that are sustainable and environmentally friendly. Full article

(This article belongs to the Special Issue The Role of Catalysts in Functionalization of C-H and C-C Bonds)

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24 pages, 4024 KiB

Open AccessEditor’s ChoiceArticle

Synthesis of Novel Key Chromophoric Intermediates via C-C Coupling Reactions

by Laila M. Nhari, Elham N. Bifari, Aisha R. Al-Marhabi, Huda A. Al-Ghamdi, Sameera N. Al-Ghamdi, Fatimah A. M. Al-Zahrani, Khalid O. Al-Footy and Reda M. El-Shishtawy

Catalysts 2022, 12(10), 1292; https://doi.org/10.3390/catal12101292 - 21 Oct 2022

Cited by 2 | Viewed by 2784

Abstract

The fundamentals of Pd-catalyzed Csp²−Csp² Miyaura borylation, Suzuki cross-coupling, and Stille cross-coupling reactions for a variety of borylated precursors based on phenothiazine (PTZ), phenoxazine (POZ), carbazole (Cz), and quinoxaline (QX) units have been explored. Three palladium-based catalysts were chosen for [...] Read more.

The fundamentals of Pd-catalyzed Csp²−Csp² Miyaura borylation, Suzuki cross-coupling, and Stille cross-coupling reactions for a variety of borylated precursors based on phenothiazine (PTZ), phenoxazine (POZ), carbazole (Cz), and quinoxaline (QX) units have been explored. Three palladium-based catalysts were chosen for this study: Pd(PPh₃)₄, Pd(PPh₃)₂Cl₂, and Pd(dppf)Cl₂, applying different reaction conditions. Around 16 desired chromophores were successfully designed and synthesized using C-C cross-coupling reactions in moderate to excellent yields, including PTZ, POZ, and Cz units coupled with QX, indolinium iodide, thienyl, phenyl, or triphenylamine moieties. Additionally, PTZ, POZ, and Cz have been employed in synthesizing various pinacol boronate ester derivatives in good to moderate yields. Interestingly, Pd(dppf)Cl₂ was found to be the best catalyst for borylation, and C-C cross-coupling reactions occurred in as little as 30 min, with an excellent yield exceeding 98%. Pd(PPh₃)₄ and Pd(PPh₃)₂Cl₂ catalyzed the reaction to obtain the desired products in moderate to good yields after a long time (20–24 h). On the other hand, the Suzuki-Miyaura cross-coupling between N-(2-methyl)hexyl carbazole pinacol boronate ester derivative 10c and three halogenated quinoxaline derivatives—4-(3-(5-bromothiophen-2-yl)quinoxalin-2-yl)benzaldehyde (27), 4-(5-(3-(5-bromothiophen-2-yl)quinoxalin-2-yl)thiophen-2-yl)benzaldehyde (30), and 4-(3-chloroquinoxalin-2-yl)benzaldehyde (25) catalyzed by Pd(PPh₃)₄—afforded three carbazole-quinoxaline chromophores (28, 30, and 31, respectively) in 2–3 h, with good to excellent yields reaching 86%. The electron-deficient QX couplers proved to be coupled efficiently using the Stille coupling reaction, which involves the coupling between electron-rich orgaostannane and electron-deficient halide. The synthesized precursors and desired chromophores were characterized by FTIR, ¹H-NMR, ¹³C-NMR, and HRMS. Full article

(This article belongs to the Special Issue The Role of Catalysts in Functionalization of C-H and C-C Bonds)

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17 pages, 4670 KiB

Open AccessArticle

Visible Light Active Magnesium Silicate–Graphitic Carbon Nitride Nanocomposites for Methylene Blue Degradation and Pb²⁺ Adsorption

by Muhmmed Ali Alnassar, Abdulmohsen Alshehri and Katabathini Narasimharao

Catalysts 2022, 12(10), 1256; https://doi.org/10.3390/catal12101256 - 17 Oct 2022

Cited by 6 | Viewed by 1987

Abstract

Magnesium silicate nanosheets (MgSiNS) and graphitic carbon nitride (g-C₃N₄) nanocomposites were produced by varying different weight percentages of g-C₃N₄. The obtained nanocomposites were characterized by various techniques such as X-Ray diffraction (XRD), Fourier transformed infrared [...] Read more.

Magnesium silicate nanosheets (MgSiNS) and graphitic carbon nitride (g-C₃N₄) nanocomposites were produced by varying different weight percentages of g-C₃N₄. The obtained nanocomposites were characterized by various techniques such as X-Ray diffraction (XRD), Fourier transformed infrared spectroscopy (FT-IR), diffuse reflectance UV–vis spectroscopy (DR UV–vis), N₂-physisorption, transmission electron microscopy (TEM), and X-ray photon spectroscopy (XPS). The photocatalytic activities of the nanocomposites were measured using visible light irradiation to degrade methylene blue (MB) and Pb²⁺ adsorption in aqueous solution. The ideal physicochemical properties such as porosity, band gap energy, and functional groups in the MgSiNS-GN20 composite (80% MgSiNS and 20 wt % of g-C₃N₄) offered high Pb²⁺ adsorption (0.005 mol/g) and excellent MB degradation efficiency (approximately 93%) at pH 7 within 200 min compared to other composites. In addition, the influences of different reaction parameters such as the effect of pH, the load catalyst, and the concentration of MB and Pb⁺² ions were examined. The obtained results indicate that inexpensive and eco-friendly MgSiNS and g-C₃N₄ composites could be recycled several times, hence representing a promising material to purify water from both organic and inorganic contaminants. Full article

(This article belongs to the Special Issue The Role of Catalysts in Functionalization of C-H and C-C Bonds)

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17 pages, 4133 KiB

Open AccessArticle

Amalgamated Titanium Oxide-Carbon Hollow Sphere/Nickel-Layered Double Hydroxide as an Efficient Photocatalyst for the Degradation of Methyl Orange

by Auhood S. Al-Soihi, Qana A. Alsulami and Mohamed Mokhtar M. Mostafa

Catalysts 2022, 12(10), 1200; https://doi.org/10.3390/catal12101200 - 09 Oct 2022

Cited by 6 | Viewed by 1718

Abstract

Investigating efficient and selective photocatalysts for water treatment can help address the energy crisis and numerous environmental issues associated with the use of current fossil fuels. As a shell, we used nickel-layered double hydroxide nanosheets on top of an anatase TiO₂-carbon [...] Read more.

Investigating efficient and selective photocatalysts for water treatment can help address the energy crisis and numerous environmental issues associated with the use of current fossil fuels. As a shell, we used nickel-layered double hydroxide nanosheets on top of an anatase TiO₂-carbon core to create an integrated photocatalyst. Materials were characterized using FTIR, XRD, SEM, HRTEM, and XPS methods for their physical-chemical properties. Using N₂ adsorption/desorption at −196 °C, BET-surface area and pore structure were determined. Diffuse reflectance UV–vis was used to determine the photocatalysts band gap. For the TiO₂-C/NiLDH amalgam, showed the lowest band gap (3.1 eV) with an exceptional ability to degrade methyl orange as an organic pollutant. Core–shell symmetry in the TiO₂-C/NiLDH amalgam provides a larger surface area (72 m²/g) for interfacial interaction and a wider base for efficient charge transfer. In subsequent tests, this photocatalyst showed a remarkable level of stability and water treatment efficacy. That the TiO₂-C/NiLDH amalgam can be used to alter solar energy and protect the environment has been demonstrated by these promising results. Full article

(This article belongs to the Special Issue The Role of Catalysts in Functionalization of C-H and C-C Bonds)

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14 pages, 3716 KiB

Open AccessEditor’s ChoiceArticle

Photocatalytic Oxidative Desulfurization of Thiophene by Exploiting a Mesoporous V₂O₅-ZnO Nanocomposite as an Effective Photocatalyst

by Maha Alhaddad, Ahmed Shawky and Zaki I. Zaki

Catalysts 2022, 12(9), 933; https://doi.org/10.3390/catal12090933 - 24 Aug 2022

Cited by 3 | Viewed by 1662

Abstract

Due to increasingly stringent environmental regulations imposed by governments throughout the world, the manufacture of low-sulfur fuels has received considerable assiduity in the petroleum industry. In this investigation, mesoporous V₂O₅-decorated two-dimensional ZnO nanocrystals were manufactured using a simple surfactant-assisted [...] Read more.

Due to increasingly stringent environmental regulations imposed by governments throughout the world, the manufacture of low-sulfur fuels has received considerable assiduity in the petroleum industry. In this investigation, mesoporous V₂O₅-decorated two-dimensional ZnO nanocrystals were manufactured using a simple surfactant-assisted sol–gel method for thiophene photocatalytic oxidative desulfurization (TPOD) at ambient temperature applying visible illumination. When correlated to pure ZnO NCs, V₂O₅-added ZnO nanocomposites dramatically improved the photocatalytic desulfurization of thiophene, and the reaction was shown to follow the pseudo-first-order model. The photocatalytic effectiveness of the 3.0 wt.% V₂O₅-ZnO photocatalyst was the greatest among all the other samples, with a rate constant of 0.0166 min⁻¹, which was 30.7 significantly greater than that of pure ZnO NCs (0.00054 min⁻¹). Compared with ZnO NCs, and owing to their synergetic effects, substantial creation of hydroxyl radical levels, lesser light scattering action, quick transport of thiophene species to the active recenters, and efficient visible-light gathering, V₂O₅-ZnO nanocomposites were found to have enhanced photocatalytic efficiency. V₂O₅-ZnO nanocomposites demonstrated outstanding stability during TPOD. Using mesoporous V₂O₅-ZnO nanocomposites, the mechanism of the charge separation process was postulated. Full article

(This article belongs to the Special Issue The Role of Catalysts in Functionalization of C-H and C-C Bonds)

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13 pages, 2806 KiB

Open AccessArticle

Electrochemical Characteristics of Nanosized Cu, Ni, and Zn Cobaltite Spinel Materials

by Mohamed Mokhtar M. Mostafa, Wejdan Bajafar, Lin Gu, Katabathini Narasimharao, Mohamed Abdel Salam, Abdulmohsen Alshehri, Nezar H. Khdary, Sulaiman Al-Faifi and Abhishek Dutta Chowdhury

Catalysts 2022, 12(8), 893; https://doi.org/10.3390/catal12080893 - 13 Aug 2022

Cited by 8 | Viewed by 2024

Abstract

For a long time, transition metal oxide systems have been considered well explored materials in heterogeneous catalysis. Amongst, the spinel-type oxides, materials such as cobaltites (Co₃O₄) received significant attention, owing to their use in many industrial applications. In the [...] Read more.

For a long time, transition metal oxide systems have been considered well explored materials in heterogeneous catalysis. Amongst, the spinel-type oxides, materials such as cobaltites (Co₃O₄) received significant attention, owing to their use in many industrial applications. In the present study, nanosized Cu, Ni, and Zn cobaltite spinel oxides were synthesized by a simple hydrothermal method. Physicochemical characterization of the synthesized materials was performed utilizing XRD, HRTEM, CO₂-TPD, and XPS techniques. The textural characteristics (BET-surface area, pore size, etc.) of samples were determined from N₂ physisorption measurements at −196 °C. The CO₂-electrocatalytic reduction was selected as a model reaction to evaluate the electrochemical performance of the synthesized spinel cobaltites. For Ni, Cu, and Zn spinel materials, hydrogen was produced as the main product at the whole potential, along with other products, such as CO and HCOOH. Despite the advantages, the catalytic electrochemical CO₂ reduction performance of spinel cobaltite catalysts is still far from adequate, which is principally ascribed to the low number of active sites combined with poor electrical conductivity. Full article

(This article belongs to the Special Issue The Role of Catalysts in Functionalization of C-H and C-C Bonds)

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13 pages, 2755 KiB

Open AccessArticle

Explorative Sonophotocatalytic Study of C-H Arylation Reaction of Pyrazoles Utilizing a Novel Sonophotoreactor for Green and Sustainable Organic Synthesis

by Tamer S. Saleh, Abdullah S. Al-Bogami, Katabathini Narasimharao, Ziya A. Khan, Iban Amenabar and Mohamed Mokhtar

Catalysts 2022, 12(8), 868; https://doi.org/10.3390/catal12080868 - 06 Aug 2022

Cited by 4 | Viewed by 1683

Abstract

The development of a mild, general, and green method for the C-H arylation of pyrazoles with relatively unreactive aryl halides is an ongoing challenge in organic synthesis. We describe herein a novel sonophotoreactor based on an ultrasonic cleaning bath and blue LED light [...] Read more.

The development of a mild, general, and green method for the C-H arylation of pyrazoles with relatively unreactive aryl halides is an ongoing challenge in organic synthesis. We describe herein a novel sonophotoreactor based on an ultrasonic cleaning bath and blue LED light (visible light) that induce copper-catalyzed monoarylation for pharmacologically relevant pyrazoles. The hybrid effect of ultrasonic irradiation and blue LED is discussed to interpret the observed synergistic action. A broad array of pyrazoles coupled with iodobenzene avoids expensive palladium metal or salts, and certain designed substrates were attained. Only comparatively inexpensive copper(I)iodide and 1,10-phenanthroline were used all together as the catalyst. The presented technique is a greener way to create C-H arylation of pyrazoles. It significantly reduces the amount of energy needed. Full article

(This article belongs to the Special Issue The Role of Catalysts in Functionalization of C-H and C-C Bonds)

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14 pages, 4061 KiB

Open AccessEditor’s ChoiceArticle

Towards the Efficient Catalytic Valorization of Chitin to N-Acylethanolamine over Ni/CeO₂ Catalyst: Exploring the Shape-Selective Reactivity

by Yifan Zheng, Lijun Lu, Wei Chen, Anmin Zheng, Aiwen Lei and Abhishek Dutta Chowdhury

Catalysts 2022, 12(5), 460; https://doi.org/10.3390/catal12050460 - 20 Apr 2022

Cited by 3 | Viewed by 2253

Abstract

Global warming and rising waste content collectively accelerate the development of renewable-derived ‘low-carbon’ chemical technologies. Among all abundant renewables, marine-/food-waste-derived chitin, the only nitrogen-containing sustainable biomass, contains the unique N-acetylglucosamine units, which could be synthetically manipulated to a plethora of organonitrogen chemicals. [...] Read more.

Global warming and rising waste content collectively accelerate the development of renewable-derived ‘low-carbon’ chemical technologies. Among all abundant renewables, marine-/food-waste-derived chitin, the only nitrogen-containing sustainable biomass, contains the unique N-acetylglucosamine units, which could be synthetically manipulated to a plethora of organonitrogen chemicals. Herein, we report the efficient one-step catalytic valorization of chitin to N-acylethanolamine over cost-effective Ni/CeO₂-based materials, which interestingly demonstrate shape-based reactivity based on CeO₂ supports. In general, all three catalysts (Ni on cubic-, rod-, and polyhedral-shaped CeO₂ supports) were active for this reaction, but they differed in their catalytic efficiency and time-monitored reaction profiles. Herein, Ni on cubic-shaped CeO₂ delivered relatively better and stable catalytic performance, along with its rod-shaped counterpart, while the polyhedral CeO₂-based material also delivered decent performance. Such interesting catalytic behavior has been corroborated by their physicochemical properties, as revealed by their characterization studies. Herein, to establish an appropriate structure-property-reactivity relationship, multimodal characterization techniques and control mechanistic experiments have been performed. This work demonstrates a concept to reduce the consumption of primary carbon resources and increase the utilization of secondary waste materials to facilitate a smooth transition from a linear economy (cf. cradle-to-grave model) to a circular economy (cf. cradle-to-cradle model). Full article

(This article belongs to the Special Issue The Role of Catalysts in Functionalization of C-H and C-C Bonds)

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21 pages, 3831 KiB

Open AccessEditor’s ChoiceReview

Recent Strategies in Nickel-Catalyzed C–H Bond Functionalization for Nitrogen-Containing Heterocycles

by Ke Yang, Zhi Li, Qingyue Hu, Mazen Elsaid, Chong Liu, Jun Chen and Haibo Ge

Catalysts 2022, 12(10), 1163; https://doi.org/10.3390/catal12101163 - 02 Oct 2022

Cited by 5 | Viewed by 2661

Abstract

N-heterocycles are ubiquitous in natural products, pharmaceuticals, organic materials, and numerous functional molecules. Among the current synthetic approaches, transition metal-catalyzed C–H functionalization has gained considerable attention in recent years due to its advantages of simplicity, high atomic economy, and the ready availability [...] Read more.

N-heterocycles are ubiquitous in natural products, pharmaceuticals, organic materials, and numerous functional molecules. Among the current synthetic approaches, transition metal-catalyzed C–H functionalization has gained considerable attention in recent years due to its advantages of simplicity, high atomic economy, and the ready availability of starting materials. In the field of N-heterocycle synthesis via C–H functionalization, nickel has been recognized as one of the most important catalysts. In this review, we will introduce nickel-catalyzed intramolecular and intermolecular pathways for N-heterocycle synthesis from 2008 to 2021. Full article

(This article belongs to the Special Issue The Role of Catalysts in Functionalization of C-H and C-C Bonds)

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28 pages, 12667 KiB

Open AccessReview

C−H Methylation Using Sustainable Approaches

by Ishika Agrawal, Gaurav Prakash, Shaeel Ahmed Al-Thabaiti, Mohamed Mokhtar and Debabrata Maiti

Catalysts 2022, 12(5), 510; https://doi.org/10.3390/catal12050510 - 02 May 2022

Cited by 5 | Viewed by 3993

Abstract

C−H methylation of sp² and sp³ carbon centers is significant in many biological processes. Methylated drug candidates show unique properties due to the change in solubility, conformation and metabolic activities. Several photo-catalyzed, electrochemical, mechanochemical and metal-free techniques that are widely utilized [...] Read more.

C−H methylation of sp² and sp³ carbon centers is significant in many biological processes. Methylated drug candidates show unique properties due to the change in solubility, conformation and metabolic activities. Several photo-catalyzed, electrochemical, mechanochemical and metal-free techniques that are widely utilized strategies in medicinal chemistry for methylation of arenes and heteroarenes have been covered in this review. Full article

(This article belongs to the Special Issue The Role of Catalysts in Functionalization of C-H and C-C Bonds)

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