Catalysts

Editorial

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3 pages, 169 KiB

Open AccessEditorial

Gold, Silver and Copper Catalysis

by Sónia Alexandra Correia Carabineiro

Catalysts 2024, 14(2), 140; https://doi.org/10.3390/catal14020140 - 10 Feb 2024

Cited by 1 | Viewed by 1519

Abstract

In terms of catalysis, the exploration of novel materials and innovative methodologies continues to drive the field forward, offering solutions to pressing challenges in various industrial applications [...] Full article

(This article belongs to the Special Issue Gold, Silver and Copper Catalysis)

Research

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11 pages, 2083 KiB

Open AccessArticle

New In Situ Catalysts Based on Nitro Functional Pyrazole Derivatives and Copper (II) Salts for Promoting Oxidation of Catechol to o-Quinone

by Abderrahim Titi, Kaoutar Zaidi, Abdullah Y. A. Alzahrani, Mohamed El Kodadi, El Bekkaye Yousfi, Anna Moliterni, Belkheir Hammouti, Rachid Touzani and Mohamed Abboud

Catalysts 2023, 13(1), 162; https://doi.org/10.3390/catal13010162 - 10 Jan 2023

Cited by 7 | Viewed by 2709

Abstract

Herein, new substituted ligands based on pyrazole (L₁–L₄) were synthesized via a one-step by condensing (1H-pyrazole-1-yl) methanol with different primary amine compounds. The present work utilized the catalytic properties of the in situ complexes formed [...] Read more.

Herein, new substituted ligands based on pyrazole (L₁–L₄) were synthesized via a one-step by condensing (1H-pyrazole-1-yl) methanol with different primary amine compounds. The present work utilized the catalytic properties of the in situ complexes formed by these ligands with various copper (II) salts viz. Cu(CH₃COO)₂, CuSO₄, CuCl₂, and Cu(NO₃)₂ for the oxidation of catechol to o-quinone. The studies showed that the catalytic activities depend on the nature and concentration of the ligand, the nature of the counterion, and the solvent. It was observed that the complex formed by L₂ and Cu(CH₃COO)₂ exhibited good catalytic activity in methanol with V_max of 41.67 µmol L⁻¹ min⁻¹ and K_m of 0.02 mol L⁻¹. Full article

(This article belongs to the Special Issue Gold, Silver and Copper Catalysis)

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19 pages, 4180 KiB

Open AccessArticle

Hydrogen Production and Degradation of Ciprofloxacin by Ag@TiO₂-MoS₂ Photocatalysts

by Abniel Machín, Kenneth Fontánez, Diego García, Paola Sampayo, Carla Colón-Cruz, Gerardo J. Claudio-Serrano, Loraine Soto-Vázquez, Edgard Resto, Florian I. Petrescu, Carmen Morant and Francisco Márquez

Catalysts 2022, 12(3), 267; https://doi.org/10.3390/catal12030267 - 27 Feb 2022

Cited by 16 | Viewed by 3844

Abstract

The photocatalytic activity of silver-based catalysts containing different amounts of molybdenum disulfide (MoS₂; 5, 10 and 20 wt.%) was evaluated by the degradation of the antibiotic ciprofloxacin and the production of hydrogen via water splitting. All the silver (Ag)-based catalysts degraded [...] Read more.

The photocatalytic activity of silver-based catalysts containing different amounts of molybdenum disulfide (MoS₂; 5, 10 and 20 wt.%) was evaluated by the degradation of the antibiotic ciprofloxacin and the production of hydrogen via water splitting. All the silver (Ag)-based catalysts degraded more than 70% of the antibiotic in 60 min. The catalyst that exhibited the best result was 5%Ag@TiO₂-P25-5%MoS₂, with ca. 91% of degradation. The control experiments and stability tests showed that photocatalysis was the degradation pathway and the selected silver-based catalysts were stable after seven cycles, with less than 2% loss of efficiency per cycle and less than 7% after seven cycles. The catalyst with the highest hydrogen production was 5%Ag@TiO₂ NWs-20%MoS₂, 1792 μmol/hg, at a wavelength of 400 nm. This amount was ca. 32 times greater than that obtained by the pristine titanium oxide nanowires catalyst. The enhancement was attributed to the high surface area of the catalysts, along with the synergism created by the silver nanoparticles and MoS₂. All the catalysts were characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Raman spectroscopy, field-emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HRTEM), Brunauer–Emmett–Teller (BET) surface area analysis and energy dispersive X-ray spectroscopy (EDS). Full article

(This article belongs to the Special Issue Gold, Silver and Copper Catalysis)

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16 pages, 10684 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Heterogeneous Gold Nanoparticle-Based Catalysts for the Synthesis of Click-Derived Triazoles via the Azide-Alkyne Cycloaddition Reaction

by Ivy L. Librando, Abdallah G. Mahmoud, Sónia A. C. Carabineiro, M. Fátima C. Guedes da Silva, Francisco J. Maldonado-Hódar, Carlos F. G. C. Geraldes and Armando J. L. Pombeiro

Catalysts 2022, 12(1), 45; https://doi.org/10.3390/catal12010045 - 31 Dec 2021

Cited by 15 | Viewed by 2756

Abstract

A supported gold nanoparticle-catalyzed strategy has been utilized to promote a click chemistry reaction for the synthesis of 1,2,3-triazoles via the azide-alkyne cycloaddition (AAC) reaction. While the advent of effective non-copper catalysts (i.e., Ru, Ag, Ir) has demonstrated the catalysis of the AAC [...] Read more.

A supported gold nanoparticle-catalyzed strategy has been utilized to promote a click chemistry reaction for the synthesis of 1,2,3-triazoles via the azide-alkyne cycloaddition (AAC) reaction. While the advent of effective non-copper catalysts (i.e., Ru, Ag, Ir) has demonstrated the catalysis of the AAC reaction, additional robust catalytic systems complementary to the copper catalyzed AAC remain in high demand. Herein, Au nanoparticles supported on Al₂O₃, Fe₂O₃, TiO₂ and ZnO, along with gold reference catalysts (gold on carbon and gold on titania supplied by the World Gold Council) were used as catalysts for the AAC reaction. The supported Au nanoparticles with metal loadings of 0.7–1.6% (w/w relative to support) were able to selectively obtain 1,4-disubstituted-1,2,3-triazoles in moderate yields up to 79% after 15 min, under microwave irradiation at 150 °C using a 0.5–1.0 mol% catalyst loading through a one-pot three-component (terminal alkyne, organohalide and sodium azide) procedure according to the “click” rules. Among the supported Au catalysts, Au/TiO₂ gave the best results. Full article

(This article belongs to the Special Issue Gold, Silver and Copper Catalysis)

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18 pages, 3114 KiB

Open AccessFeature PaperArticle

Effect of the Metal Deposition Order on Structural, Electronic and Catalytic Properties of TiO₂-Supported Bimetallic Au-Ag Catalysts in 1-Octanol Selective Oxidation

by Yulia Kotolevich, Ekaterina Pakrieva, Ekaterina Kolobova, Mario H. Farías, Nina Bogdanchikova, Vicente Cortés Corberán, Daria Pichugina, Nadezhda Nikitina, Sónia A. C. Carabineiro and Alexey Pestryakov

Catalysts 2021, 11(7), 799; https://doi.org/10.3390/catal11070799 - 30 Jun 2021

Cited by 1 | Viewed by 2362

Abstract

Au and Ag were deposited on TiO₂ modified with Ce, La, Fe or Mg in order to obtain bimetallic catalysts to be used for liquid-phase oxidation of 1-octanol. The effects of the deposition order of gold and silver, and the nature of [...] Read more.

Au and Ag were deposited on TiO₂ modified with Ce, La, Fe or Mg in order to obtain bimetallic catalysts to be used for liquid-phase oxidation of 1-octanol. The effects of the deposition order of gold and silver, and the nature of the support modifying additives and redox pretreatments on the catalytic properties of the bimetallic Au-Ag catalysts were studied. Catalysts were characterized by low-temperature nitrogen adsorption–desorption, energy dispersive spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy and ultraviolet-visible diffuse reflectance spectroscopy. It was found that pretreatments with hydrogen and oxygen at 300 °C significantly decreased the activity of AuAg catalysts (silver was deposited first) and had little effect on the catalytic properties of AgAu samples (gold was deposited first). The density functional theory method demonstrated that the adsorption energy of 1-octanol increased for all positively charged Au_xAg_y^q (x + y = 10, with a charge of q = 0 or +1) clusters compared with the neutral counterparts. Lanthanum oxide was a very effective promoter for both monometallic and bimetallic gold and silver catalysts in the studied process. Full article

(This article belongs to the Special Issue Gold, Silver and Copper Catalysis)

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17 pages, 3384 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Shape Effects of Ceria Nanoparticles on the Water‒Gas Shift Performance of CuO_x/CeO₂ Catalysts

by Maria Lykaki, Sofia Stefa, Sónia A. C. Carabineiro, Miguel A. Soria, Luís M. Madeira and Michalis Konsolakis

Catalysts 2021, 11(6), 753; https://doi.org/10.3390/catal11060753 - 21 Jun 2021

Cited by 15 | Viewed by 2976

Abstract

The copper–ceria (CuO_x/CeO₂) system has been extensively investigated in several catalytic processes, given its distinctive properties and considerable low cost compared to noble metal-based catalysts. The fine-tuning of key parameters, e.g., the particle size and shape of individual counterparts, [...] Read more.

The copper–ceria (CuO_x/CeO₂) system has been extensively investigated in several catalytic processes, given its distinctive properties and considerable low cost compared to noble metal-based catalysts. The fine-tuning of key parameters, e.g., the particle size and shape of individual counterparts, can significantly affect the physicochemical properties and subsequently the catalytic performance of the binary oxide. To this end, the present work focuses on the morphology effects of ceria nanoparticles, i.e., nanopolyhedra (P), nanocubes (C), and nanorods (R), on the water–gas shift (WGS) performance of CuO_x/CeO₂ catalysts. Various characterization techniques were employed to unveil the effect of shape on the structural, redox and surface properties. According to the acquired results, the support morphology affects to a different extent the reducibility and mobility of oxygen species, following the trend: R > P > C. This consequently influences copper–ceria interactions and the stabilization of partially reduced copper species (Cu⁺) through the Cu²⁺/Cu⁺ and Ce⁴⁺/Ce³⁺ redox cycles. Regarding the WGS performance, bare ceria supports exhibit no activity, while the addition of copper to the different ceria nanostructures alters significantly this behaviour. The CuO_x/CeO₂ sample of rod-like morphology demonstrates the best catalytic activity and stability, approaching the thermodynamic equilibrium conversion at 350 °C. The greater abundance in loosely bound oxygen species, oxygen vacancies and highly dispersed Cu⁺ species can be mainly accounted for its superior catalytic performance. Full article

(This article belongs to the Special Issue Gold, Silver and Copper Catalysis)

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25 pages, 5385 KiB

Open AccessArticle

Cu-Catalyzed Hydrodehalogenation of Brominated Aromatic Pollutants in Aqueous Solution

by Tomáš Weidlich, Barbora Kamenická, Ludvík Beneš, Veronika Čičmancová, Alena Komersová, Jiří Čermák and Petr Švec

Catalysts 2021, 11(6), 699; https://doi.org/10.3390/catal11060699 - 31 May 2021

Cited by 4 | Viewed by 2365

Abstract

The catalytic effect of copper in Devarda’s Al-Cu-Zn alloy (Dev. alloy) and sole metallic copper, copper salts and copper oxides in the coaction of NaBH₄ within the hydrodehalogenation (HDH) of polybrominated phenols, such as the herbicide Bromoxynil in alkaline aqueous solution has [...] Read more.

The catalytic effect of copper in Devarda’s Al-Cu-Zn alloy (Dev. alloy) and sole metallic copper, copper salts and copper oxides in the coaction of NaBH₄ within the hydrodehalogenation (HDH) of polybrominated phenols, such as the herbicide Bromoxynil in alkaline aqueous solution has been investigated. Namely, the hydrodebromination (HDB) activity of Dev. alloy/NaOH system has been compared to heterogeneous Cu-based catalysts using NaBH₄ as a reductant. Differences in the solid-state structures of used Cu-based heterogeneous catalysts after the mentioned HDB process have been studied using the powder XRD and SEM techniques. It was found that some of the used copper-based catalysts are reusable and reasonably effective even at room temperature. Efficiency of the most promising copper-based reduction systems (Dev. alloy/NaOH and Cu-based catalysts/NaBH₄) have been successfully tested within the HDB of industrially important brominated flame retardant tetrabromobisphenol A (TBBPA). Dev. alloy/NaOH and Cu-based catalyst generated in-situ within the CuSO₄/NaBH₄ produced were recognized as the most active HDB agents for complete debromination of both BRX and TBBPA. Full article

(This article belongs to the Special Issue Gold, Silver and Copper Catalysis)

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13 pages, 4709 KiB

Open AccessArticle

Preparation of TiO₂/Ag[BMIM]Cl Composites and Their Visible Light Photocatalytic Properties for the Degradation of Rhodamine B

by Xi Lin and Yanxia Li

Catalysts 2021, 11(6), 661; https://doi.org/10.3390/catal11060661 - 23 May 2021

Cited by 10 | Viewed by 2472

Abstract

In order to degrade toxic pollutants such as dyes during the process of sewage treatment, considerable attention has been paid to photocatalytic technologies. In this paper, TiO₂/Ag[BMIM]Cl (1-butyl-3-methyl imidazolium chloride ([BMIM]Cl)) nanocomposites were prepared with TiO₂ as the carrier, silver [...] Read more.

In order to degrade toxic pollutants such as dyes during the process of sewage treatment, considerable attention has been paid to photocatalytic technologies. In this paper, TiO₂/Ag[BMIM]Cl (1-butyl-3-methyl imidazolium chloride ([BMIM]Cl)) nanocomposites were prepared with TiO₂ as the carrier, silver ions as dopants and ionic liquids (IL) as modifiers. The morphologies, microstructures, crystalline structure and optical properties of the TiO₂/Ag[BMIM]Cl nanospheres are investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD), total organic carbon (TOC), and UV-vis diffuse reflectance spectrum (UV-vis DRS) techniques. The TiO₂/Ag[BMIM]Cl nanocomposites can selectively degrade rhodamine B (Rh B) under visible light because of the unstable quaternary ammonium salt. The as-obtained nanocomposites exhibit better photocatalytic activity performance than pure TiO₂, TiO₂/IL, and TiO₂/Ag⁺. The experimental results show that the Rh B degradation rate can reach 98.87% under optimized producing conditions by using the TiO₂/Ag[BMIM]Cl composites as the catalyzer. It shows that simultaneous doping with silver ions and ionic liquids can significantly improve the photocatalytic activity of TiO₂ in Rh B degradation, indicating the formation of photosensitive AgCl in the process of TiO₂/Ag[BMIM]Cl preparation. Ag⁺ and IL addition exchange the band gap of TiO₂ and lengthen the visible wavelength range of the composite. The material has the advantages of low cost, facile preparation and reusability with the excellent degradation effect of Rh B. Full article

(This article belongs to the Special Issue Gold, Silver and Copper Catalysis)

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18 pages, 3448 KiB

Open AccessEditor’s ChoiceArticle

The Efficacy of Silver Nitrate (AgNO₃) as a Coating Agent to Protect Paper against High Deteriorating Microbes

by Amr Fouda, Gomaa Abdel-Maksoud, Hosam A. Saad, Adil A. Gobouri, Zuhair M. Mohammedsaleh and Mohamad Abdel-Haleem El-Sadany

Catalysts 2021, 11(3), 310; https://doi.org/10.3390/catal11030310 - 26 Feb 2021

Cited by 37 | Viewed by 6673

Abstract

This study focuses on the efficacy of silver nitrate (AgNO₃) as a coating agent used to preserve papers against microbial deterioration. To this end, the in vitro cytotoxicity of AgNO₃ was assessed against two normal cell lines, WI-38 and HFB-4, [...] Read more.

This study focuses on the efficacy of silver nitrate (AgNO₃) as a coating agent used to preserve papers against microbial deterioration. To this end, the in vitro cytotoxicity of AgNO₃ was assessed against two normal cell lines, WI-38 and HFB-4, to detect a safe dose that can be used as a coating agent, which was 80 µg mL⁻¹. Bacillus subtilis B3 and Penicillium chrysogenum F9 were selected as high deteriorating microbes, previously isolated from a historical manuscript dating back to 1677 A.-D. The microbial growth inhibition, color change, mechanical properties, and cellulosic fibers of untreated/treated papers were evaluated. The data showed the efficacy of AgNO₃ to inhibit the growth of B. subtilis with a percentage of 100% after 7 days, while it inhibits the growth of P. chrysogenum with a percentage of 85.9 ± 1.1% after 21 days. The color and mechanical properties of treated paper in the presence/absence of microbial inoculation were slightly changed, although they changed greatly due to microbial growth in the absence of AgNO₃. The EDX analysis confirmed the successful adsorption of Ag-ion on papers, with a weight percentage of 1.9%. The cellulosic fibers of untreated paper in the presence of microbial growth were highly deteriorated as compared with treated and standard filter paper (shown by FT-IR and SEM). Full article

(This article belongs to the Special Issue Gold, Silver and Copper Catalysis)

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15 pages, 3585 KiB

Open AccessFeature PaperArticle

The Catalytic Activity of Carbon-Supported Cu(I)-Phosphine Complexes for the Microwave-Assisted Synthesis of 1,2,3-Triazoles

by Ivy L. Librando, Abdallah G. Mahmoud, Sónia A. C. Carabineiro, M. Fátima C. Guedes da Silva, Carlos F. G. C. Geraldes and Armando J. L. Pombeiro

Catalysts 2021, 11(2), 185; https://doi.org/10.3390/catal11020185 - 31 Jan 2021

Cited by 16 | Viewed by 3378

Abstract

A set of Cu(I) complexes with 3,7-diacetyl-1,3,7-triaza-5-phosphabicyclo-[3.3.1]nonane (DAPTA) phosphine ligands viz. [CuX(κP-DAPTA)₃] (1: X = Br; 2: X = I) and [Cu(μ-X)(κP-DAPTA)₂]₂ (3: X = Br; 4: X = I) were immobilized [...] Read more.

A set of Cu(I) complexes with 3,7-diacetyl-1,3,7-triaza-5-phosphabicyclo-[3.3.1]nonane (DAPTA) phosphine ligands viz. [CuX(κP-DAPTA)₃] (1: X = Br; 2: X = I) and [Cu(μ-X)(κP-DAPTA)₂]₂ (3: X = Br; 4: X = I) were immobilized on activated carbon (AC) and multi-walled carbon nanotubes (CNT), as well as on these materials after surface functionalization. The immobilized copper(I) complexes have shown favorable catalytic activity for the one-pot, microwave-assisted synthesis of 1,2,3-triazoles via the azide-alkyne cycloaddition reaction (CuAAC). The heterogenized systems with a copper loading of only 1.5–1.6% (w/w relative to carbon), established quantitative conversions after 15 min, at 80 °C, using 0.5 mol% of catalyst loading (relative to benzyl bromide). The most efficient supports concerning heterogenization were CNT treated with nitric acid and NaOH, and involving complexes 2 and 4 (in the same order, 2_CNT-ox-Na and 4_CNT-ox-Na). The immobilized catalysts can be recovered and recycled by simple workup and reused up to four consecutive cycles although with loss of activity. Full article

(This article belongs to the Special Issue Gold, Silver and Copper Catalysis)

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12 pages, 5051 KiB

Open AccessArticle

Catalytic Activity of Beta-Cyclodextrin-Gold Nanoparticles Network in Hydrogen Evolution Reaction

by Qui Quach, Erik Biehler, Ahmed Elzamzami, Clay Huff, Julia M. Long and Tarek M. Abdel-Fattah

Catalysts 2021, 11(1), 118; https://doi.org/10.3390/catal11010118 - 15 Jan 2021

Cited by 19 | Viewed by 3314

Abstract

The current climate crisis warrants investigation into alternative fuel sources. The hydrolysis reaction of an aqueous hydride precursor, and the subsequent production of hydrogen gas, prove to be a viable option. A network of beta-cyclodextrin capped gold nanoparticles (BCD-AuNP) was synthesized and subsequently [...] Read more.

The current climate crisis warrants investigation into alternative fuel sources. The hydrolysis reaction of an aqueous hydride precursor, and the subsequent production of hydrogen gas, prove to be a viable option. A network of beta-cyclodextrin capped gold nanoparticles (BCD-AuNP) was synthesized and subsequently characterized by Powder X-Ray Diffraction (P-XRD), Fourier Transform Infrared (FTIR), Transmission Electron Microscopy (TEM), and Ultraviolet-Visible Spectroscopy (UV-VIS) to confirm the presence of gold nanoparticles as well as their size of approximately 8 nm. The catalytic activity of the nanoparticles was tested in the hydrolysis reaction of sodium borohydride. The gold catalyst performed best at 303 K producing 1.377 mL min⁻¹ mL_cat⁻¹ of hydrogen. The activation energy of the catalyst was calculated to be 54.7 kJ/mol. The catalyst resisted degradation in reusability trials, continuing to produce hydrogen gas in up to five trials. Full article

(This article belongs to the Special Issue Gold, Silver and Copper Catalysis)

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13 pages, 1992 KiB

Open AccessFeature PaperArticle

Porphyrin–Nanodiamond Hybrid Materials—Active, Stable and Reusable Cyclohexene Oxidation Catalysts

by Lucas D. Dias, Fábio M. S. Rodrigues, Mário J. F. Calvete, Sónia A. C. Carabineiro, Marisa D. Scherer, Anderson R. L. Caires, Josephus G. Buijnsters, José L. Figueiredo, Vanderlei S. Bagnato and Mariette M. Pereira

Catalysts 2020, 10(12), 1402; https://doi.org/10.3390/catal10121402 - 1 Dec 2020

Cited by 10 | Viewed by 3214

Abstract

The quest for active, yet “green” non-toxic catalysts is a continuous challenge. In this work, covalently linked hybrid porphyrin–nanodiamonds were prepared via ipso nitro substitution reaction and characterized by X-ray photoelectron spectroscopy (XPS), fluorescence spectroscopy, infrared spectroscopy (IR) and thermogravimetry-differential scanning calorimetry (TG-DSC). [...] Read more.

The quest for active, yet “green” non-toxic catalysts is a continuous challenge. In this work, covalently linked hybrid porphyrin–nanodiamonds were prepared via ipso nitro substitution reaction and characterized by X-ray photoelectron spectroscopy (XPS), fluorescence spectroscopy, infrared spectroscopy (IR) and thermogravimetry-differential scanning calorimetry (TG-DSC). The amine-functionalized nanodiamonds (ND@NH₂) and 2-nitro-5,10,15,20-tetra(4-trifluoromethylphenyl)porphyrin covalently linked to nanodiamonds (ND@βNH-TPPpCF₃) were tested using Allium cepa as a plant model, and showed neither phytotoxicity nor cytotoxicity. The hybrid nanodiamond–copper(II)–porphyrin material ND@βNH-TPPpCF₃-Cu(II) was also evaluated as a reusable catalyst in cyclohexene allylic oxidation, and displayed a remarkable turnover number (TON) value of ≈265,000, using O₂ as green oxidant, in the total absence of sacrificial additives, which is the highest activity ever reported for said allylic oxidation. Additionally, ND@βNH-TPPpCF₃-Cu(II) could be easily separated from the reaction mixture by centrifugation, and reused in three consecutive catalytic cycles without major loss of activity. Full article

(This article belongs to the Special Issue Gold, Silver and Copper Catalysis)

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Review

Jump to: Editorial, Research

30 pages, 15061 KiB

Open AccessReview

Copper-Catalyzed Reactions of Aryl Halides with N-Nucleophiles and Their Possible Application for Degradation of Halogenated Aromatic Contaminants

by Tomáš Weidlich, Martina Špryncová and Alexander Čegan

Catalysts 2022, 12(8), 911; https://doi.org/10.3390/catal12080911 - 18 Aug 2022

Cited by 7 | Viewed by 5668

Abstract

This review summarizes recent applications of copper or copper-based compounds as a nonprecious metal catalyst in N-nucleophiles-based dehalogenation (DH) reactions of halogenated aromatic compounds (Ar-Xs). Cu-catalyzed DH enables the production of corresponding nonhalogenated aromatic products (Ar-Nu), which are much more biodegradable and can [...] Read more.

This review summarizes recent applications of copper or copper-based compounds as a nonprecious metal catalyst in N-nucleophiles-based dehalogenation (DH) reactions of halogenated aromatic compounds (Ar-Xs). Cu-catalyzed DH enables the production of corresponding nonhalogenated aromatic products (Ar-Nu), which are much more biodegradable and can be mineralized during aerobic wastewater treatment or which are principally further applicable. Based on available knowledge, the developed Cu-based DH methods enable the utilization of amines for effective cleavage of aryl-halogen bonds in organic solvents or even in an aqueous solution. Full article

(This article belongs to the Special Issue Gold, Silver and Copper Catalysis)

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45 pages, 12138 KiB

Open AccessFeature PaperReview

Acenaphthene-Based N-Heterocyclic Carbene Metal Complexes: Synthesis and Application in Catalysis

by Paulina Baczewska, Katarzyna Śniady, Wioletta Kośnik and Michał Michalak

Catalysts 2021, 11(8), 972; https://doi.org/10.3390/catal11080972 - 14 Aug 2021

Cited by 11 | Viewed by 5310

Abstract

N-Heterocyclic carbene (NHC) ligands have become a privileged structural motif in modern homogenous and heterogeneous catalysis. The last two decades have brought a plethora of structurally and electronically diversified carbene ligands, enabling the development of cutting-edge transformations, especially in the area of [...] Read more.

N-Heterocyclic carbene (NHC) ligands have become a privileged structural motif in modern homogenous and heterogeneous catalysis. The last two decades have brought a plethora of structurally and electronically diversified carbene ligands, enabling the development of cutting-edge transformations, especially in the area of carbon-carbon bond formation. Although most of these were accomplished with common imidazolylidene and imidazolinylidene ligands, the most challenging ones were only accessible with the acenaphthylene-derived N-heterocyclic carbene ligands bearing a π-extended system. Their superior σ-donor capabilities with simultaneous ease of modification of the rigid backbone enhance the catalytic activity and stability of their transition metal complexes, which makes BIAN-NHC (BIAN—bis(imino)acenaphthene) ligands an attractive tool for the development of challenging reactions. The present review summarizes synthetic efforts towards BIAN-NHC metal complexes bearing acenaphthylene subunits and their applications in modern catalysis, with special emphasis put on recently developed enantioselective processes. Full article

(This article belongs to the Special Issue Gold, Silver and Copper Catalysis)

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34 pages, 7660 KiB

Open AccessReview

The Influence of Copper on Halogenation/Dehalogenation Reactions of Aromatic Compounds and Its Role in the Destruction of Polyhalogenated Aromatic Contaminants

by Tomáš Weidlich

Catalysts 2021, 11(3), 378; https://doi.org/10.3390/catal11030378 - 14 Mar 2021

Cited by 12 | Viewed by 6625

Abstract

The effect of copper and its compounds on halogenation and dehalogenation of aromatic compounds will be discussed in the proposed article. Cu oxidized to appropriate halides is an effective halogenation catalyst not only for the synthesis of halogenated benzenes or their derivatives as [...] Read more.

The effect of copper and its compounds on halogenation and dehalogenation of aromatic compounds will be discussed in the proposed article. Cu oxidized to appropriate halides is an effective halogenation catalyst not only for the synthesis of halogenated benzenes or their derivatives as desired organic fine chemicals, but is also an effective catalyst for the undesirable formation of thermodynamically stable and very toxic polychlorinated and polybrominated aromatic compounds such as polychlorinated biphenyls, dibenzo-p-dioxins and dibenzofurans accompanied incineration of waste contaminated with halogenated compounds or even inorganic halides. With appropriate change in reaction conditions, copper and its alloys or oxides are also able to effectively catalyze dehalogenation reactions, as will be presented in this review. Full article

(This article belongs to the Special Issue Gold, Silver and Copper Catalysis)

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