10th Anniversary of Catalysts: Molecular Catalysis

A special issue of Catalysts (ISSN 2073-4344). This special issue belongs to the section "Catalysis in Organic and Polymer Chemistry".

Deadline for manuscript submissions: closed (31 December 2021) | Viewed by 32817

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Laboratory of Industrial and Synthetic Organic Chemistry (LISOC), Department of Chemistry and Chemical Technologies, University of Calabria, Via Pietro Bucci 12/C, 87036 Arcavacata di Rende, CS, Italy
Interests: innovative syntheses of high-value molecules through catalytic process; new syntheses of heterocyclic compounds of pharmaceutical interest; carbonylation catalyzed chemistry; application of unconventional solvents in advanced organic synthesis; synthesis of novel materials for advanced applications
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1. Division of Applied Chemistry, Faculty of Engineering, Hokkaido University, Sapporo, Hokkaido 060-8628, Japan
2. Frontier Chemistry Center, Faculty of Engineering, Hokkaido University, Sapporo, Hokkaido 060-8628, Japan
Interests: dual catalysis; allylic alcohol; asymmetric cyanation; combined metal catalyst; unsaturated ketone; unsaturated carbonyl compound; asymmetric isomerization; box ligands; Cu complexes; Pd nanoparticles; photocyclization; kinetic resolution; DPEN; DAIPEN; XylBINAP; BINAP; TolBINAP; DMAPEN; PICA; IPHAN; LiCl; organometallic chemistry; synthetic organic chemistry (4602); organometallic chemistry (4072); asymmetric catalysis (4072); research areas applied chemistry/functional materials chemistry
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Dipartimento di Chimica, Università degli Studi di Milano, Via C. Golgi 19, 20133 Milan, Italy
Interests: homogeneous catalysis; carbonylation reactions; nitroarene reductive cyclization; nitroarene reductive carbonylation; catalytic synthesis of isocyanates, carbamates, and ureas; oxidative carbonylation of amines; nitrogen-enriched graphitic metal catalysts; synthesis and use of nitrogen ligands
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Department of Organic Chemistry, Faculty of Science, Charles University, Hlavova 8, 12843 Prague, Czech Republic
Interests: transition metal complex catalysis; asymmetric synthesis; organometallic chemistry; organocatalysis
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Dipartimento di Chimica e Biologia and NANOMATES Research Centre for NANOMAterials and nanoTEchnology at Salerno University, Università degli Studi di Salerno, Via Giovanni Paolo II, 84084 Fisciano (SA), Italy
Interests: nanoparticle; polymerization catalysis; organometallics; coupling of carbon dioxid; catalytic mechanisms

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Centro de Quimica Estrutural, Instituto Superior Tecnico, Lisbon, Portugal
Interests: coordination chemistry; oxidation catalysis; electrocatalysis; alkane functionalization; carboxylation; C-C coupling; non-covalent interactions in synthesis
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Graduate School of Human and Environmental Studies, Kyoto University, Sakyo-ku, Kyoto, Japan
Interests: organometallic chemistry; synthetic organic chemistry; coordination chemistry; dehydrogenation of organic molecules; hydrogen transfer reactions; hydrogen storage using organic hydrides; hydrogen production from sustainable resources
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Department of Chemistry and Biology, University of Salerno, 84084 Fisciano, Italy
Interests: polyolefins; polycarbonates; polyesters; carbon dioxide; bio-based polymers; homogeneous catalysis

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School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan
Interests: cross coupling; palladium catalyst; homogeneous/heterogeneous catalyst; selective reaction; allylic substitution; carbonylation; C-H activation; reaction mechanism; organometallic chemistry
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Department of Organic and Inorganic Chemistry, University of Oviedo, Julián Clavería 8, 33006 Oviedo, Spain
Interests: homogeneous catalysis; aqueous catalysis; green chemistry; organometallic and coordination chemistry; alternative reaction media; organic synthesis
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Special Issue Information

Dear Colleagues,

We are happy to invite you to the Special Issue titled “10th Anniversary of Catalysts: Molecular Catalysts”. This Special Issue is organized by some editorial board members of Catalysts in the Organic and Polymer Chemistry Section. We will be accepting manuscripts related to molecular catalysis, including metal catalyzed organic transformations (efficient organic synthesis), polymerization, mechanistic studies, synthesis of functional polymers, etc. The topic is broad, and any articles and reviews related to this topic will be acceptable on the basis of documents described in the section information (https://www.mdpi.com/journal/catalysts/sections/catalysis_in_organic_and_polymer_chemistry). Moreover, in order to be more visible and have a greater impact, we encourage submissions on this topic from a wide range of authors, and you are welcome to invite relevant authors to participate. We are looking forward to receiving many papers on this exciting occasion. 

Please contact the guest editor in chief if you have questions

Prof. Kotohiro Nomura
Prof. Dr. Raffaella Mancuso
Prof. Dr. Takeshi Ohkuma
Prof. Dr. Fabio Ragaini
Prof. Dr. Martin Kotora
Prof. Dr. Alfonso Grassi
Prof. Dr. Carl Redshaw
Prof. Armando Pombeiro
Prof. Dr. Ken-ichi Fujita
Prof. Dr. Carmine Capacchione
Prof. Dr. Kei Manabe
Prof. Dr. Victorio Cadierno
Guest Editors

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Catalysts is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

 

Keywords

  • molecular catalysis
  • organic transformations
  • fine chemicals
  • polymers
  • polymerization
  • green sustainable catalysis

Published Papers (13 papers)

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Editorial

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2 pages, 188 KiB  
Editorial
10th Anniversary of Catalysts: Molecular Catalysis
by Kotohiro Nomura, Raffaella Mancuso, Takeshi Ohkuma, Fabio Ragaini, Martin Kotora, Alfonso Grassi, Carl Redshaw, Armando Pombeiro, Ken-ichi Fujita, Carmine Capacchione, Kei Manabe and Victorio Cadierno
Catalysts 2022, 12(12), 1584; https://doi.org/10.3390/catal12121584 - 06 Dec 2022
Viewed by 1041
Abstract
On the occasion of this Special Issue, I would like to present an editorial message on this good occasion [...] Full article
(This article belongs to the Special Issue 10th Anniversary of Catalysts: Molecular Catalysis)

Research

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10 pages, 3625 KiB  
Article
Solution XAS Analysis for Reactions of Phenoxide-Modified (Arylimido)vanadium(V) Dichloride and (Oxo)vanadium(V) Complexes with Al Alkyls: Effect of Al Cocatalyst in Ethylene (Co)polymerization
by Kotohiro Nomura, Itsuki Izawa, Mahaharu Kuboki, Kensuke Inoue, Hirotaka Aoki and Ken Tsutsumi
Catalysts 2022, 12(2), 198; https://doi.org/10.3390/catal12020198 - 06 Feb 2022
Cited by 5 | Viewed by 1953
Abstract
V K-edge XANES (XANES = X-ray Absorption Near Edge Structure) spectra of the reaction solution of V(NAr)Cl2(OAr) (1, Ar = 2,6-Me2C6H3) with halogenated Al alkyls (Me2AlCl, Et2AlCl, EtAlCl2 [...] Read more.
V K-edge XANES (XANES = X-ray Absorption Near Edge Structure) spectra of the reaction solution of V(NAr)Cl2(OAr) (1, Ar = 2,6-Me2C6H3) with halogenated Al alkyls (Me2AlCl, Et2AlCl, EtAlCl2, 50 equiv) in toluene showed low energy shifts (2.6–3.6 eV on the basis of inflection point in the photon energy) in the edge absorption accompanying slight shift to low photon energy in the pre-edge peak (λmax values); a similar spectrum was observed when the reaction of 1 with Me2AlCl was conducted in n-hexane. These results strongly suggest a formation of similar vanadium(III) species irrespective of kind of Al alkyls and solvent (toluene or n-hexane). Significant low-energy shifts in the edge absorption accompanied with diminishing the strong pre-edge absorption were also observed when VOCl3 or VO(OiPr)3 was treated with Me2AlCl (10 equiv) in toluene, clearly indicating a formation of low oxidation state vanadium species accompanied with certain structural changes (from tetrahedral to octahedral) in solution. Full article
(This article belongs to the Special Issue 10th Anniversary of Catalysts: Molecular Catalysis)
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15 pages, 9503 KiB  
Article
Synthesis of Indoles by Palladium-Catalyzed Reductive Cyclization of β-Nitrostyrenes with Phenyl Formate as a CO Surrogate
by Francesco Ferretti, Manar Ahmed Fouad and Fabio Ragaini
Catalysts 2022, 12(1), 106; https://doi.org/10.3390/catal12010106 - 17 Jan 2022
Cited by 7 | Viewed by 2319
Abstract
The reductive cyclization of suitably substituted organic nitro compounds by carbon monoxide is a very appealing technique for the synthesis of heterocycles because of its atom efficiency and easiness of separation of the only stoichiometric byproduct CO2, but the need for [...] Read more.
The reductive cyclization of suitably substituted organic nitro compounds by carbon monoxide is a very appealing technique for the synthesis of heterocycles because of its atom efficiency and easiness of separation of the only stoichiometric byproduct CO2, but the need for pressurized CO has hampered its diffusion. We have recently reported on the synthesis of indoles by reductive cyclization of o-nitrostyrenes using phenyl formate as a CO surrogate, using a palladium/1,10-phenanthroline complex as catalyst. However, depending on the desired substituents on the structure, the use of β-nitrostyrenes as alternative reagents may be advantageous. We report here the results of our study on the possibility to use phenyl formate as a CO surrogate in the synthesis of indoles by reductive cyclization of β-nitrostyrenes, using PdCl2(CH3CN)2 + phenanthroline as the catalyst. It turned out that good results can be obtained when the starting nitrostyrene bears an aryl substituent in the alpha position. However, when no such substituent is present, only fair yield of indole can be obtained because the base required to decompose the formate also catalyzes an oligo-polymerization of the starting styrene. The reaction can be performed in a single glass pressure tube, a cheap and easily available piece of equipment. Full article
(This article belongs to the Special Issue 10th Anniversary of Catalysts: Molecular Catalysis)
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24 pages, 9909 KiB  
Article
A 5-(2-Pyridyl)tetrazolate Complex of Molybdenum(VI), Its Structure, and Transformation to a Molybdenum Oxide-Based Hybrid Heterogeneous Catalyst for the Epoxidation of Olefins
by Martinique S. Nunes, Diana M. Gomes, Ana C. Gomes, Patrícia Neves, Ricardo F. Mendes, Filipe A. Almeida Paz, André D. Lopes, Anabela A. Valente, Isabel S. Gonçalves and Martyn Pillinger
Catalysts 2021, 11(11), 1407; https://doi.org/10.3390/catal11111407 - 20 Nov 2021
Cited by 9 | Viewed by 3311
Abstract
There is a considerable practical interest in discovering new ways to obtain organomolybdenum heterogeneous catalysts for olefin epoxidation that are easier to recover and reuse and display enhanced productivity. In this study, the complex salt (H2pytz)[MoO2Cl2(pytz)] ( [...] Read more.
There is a considerable practical interest in discovering new ways to obtain organomolybdenum heterogeneous catalysts for olefin epoxidation that are easier to recover and reuse and display enhanced productivity. In this study, the complex salt (H2pytz)[MoO2Cl2(pytz)] (1) (Hpytz = 5-(2-pyridyl)tetrazole) has been prepared, structurally characterized, and employed as a precursor for the hydrolysis-based synthesis of a microcrystalline molybdenum oxide/organic hybrid material formulated as [MoO3(Hpytz)] (2). In addition to single-crystal X-ray diffraction (for 1), compounds 1 and 2 were characterized by FT-IR and Raman spectroscopies, solid-state 13C{1H} cross-polarization (CP) magic-angle spinning (MAS) NMR, and scanning electron microscopy (SEM). Compounds 1 and 2 were evaluated as olefin epoxidation catalysts using the model reaction of cis-cyclooctene (Cy8) with tert-butyl hydroperoxide (TBHP), at 70 °C, which gave 100% epoxide selectivity up to 100% conversion. While 1 behaved as a homogeneous catalyst, hybrid 2 behaved as a heterogeneous catalyst and could be recovered for recycling without showing structural degradation or loss of catalytic performance over consecutive reaction cycles. The substrate scope was broadened to monoterpene DL-limonene (Lim) and biobased unsaturated fatty acid methyl esters, methyl oleate (MeOle), and methyl linoleate (MeLin), which gave predominantly epoxide products. Full article
(This article belongs to the Special Issue 10th Anniversary of Catalysts: Molecular Catalysis)
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10 pages, 20917 KiB  
Article
Synthesis of 2-Methylquinoxaline Derivatives from Glycerol and Diamines Catalyzed by Iridium Complexes Bearing an N-Heterocyclic Carbene Ligand
by Toshiki Tanaka, Akane Enomoto, Shohichi Furukawa and Ken-ichi Fujita
Catalysts 2021, 11(10), 1200; https://doi.org/10.3390/catal11101200 - 30 Sep 2021
Cited by 5 | Viewed by 1887
Abstract
2-Methylquinoxaline derivatives are widely used as intermediates in the synthesis of pharmaceuticals, natural products, and dyes; however, their syntheses usually require excess reagents, making them environmentally burdensome. Meanwhile, glycerol can be sustainably obtained in large quantities as a by-product in the production of [...] Read more.
2-Methylquinoxaline derivatives are widely used as intermediates in the synthesis of pharmaceuticals, natural products, and dyes; however, their syntheses usually require excess reagents, making them environmentally burdensome. Meanwhile, glycerol can be sustainably obtained in large quantities as a by-product in the production of biodiesel fuel using waste oil as a raw material. Thus, it is worthwhile to develop a new catalytic system that utilizes glycerol as a C3 source. In this study, an efficient catalytic system was developed to obtain 2-methylquinoxaline derivatives from glycerol and 1,2-phenylenediamines. This system is beneficial because it is environmentally friendly and has excellent atom efficiency. Full article
(This article belongs to the Special Issue 10th Anniversary of Catalysts: Molecular Catalysis)
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19 pages, 7237 KiB  
Article
Alkoxy-Functionalized Schiff-Base Ligation at Aluminum and Zinc: Synthesis, Structures and ROP Capability
by Xin Zhang, Kai Chen, Melissa Chicoma, Kimberly Goins, Timothy J. Prior, Terence A. Nile and Carl Redshaw
Catalysts 2021, 11(9), 1090; https://doi.org/10.3390/catal11091090 - 09 Sep 2021
Cited by 7 | Viewed by 1909
Abstract
The Schiff-base compounds 2,4-di-tert-butyl-6-(((3,4,5-trimethoxyphenyl)imino)methyl)phenol (L1H), 2,4-di-tert-butyl-6-(((2,4,6-trimethoxyphenyl)imino)methyl)phenol (L2H), 2,4-di-tert-butyl-6-(((2,4-trimethoxyphenyl)imino)methyl)phenol) (L3H) derived from anilines bearing methoxy substituents have been employed in the preparation of alkylaluminum and zinc complexes. Molecular structure determinations reveal mono-chelate [...] Read more.
The Schiff-base compounds 2,4-di-tert-butyl-6-(((3,4,5-trimethoxyphenyl)imino)methyl)phenol (L1H), 2,4-di-tert-butyl-6-(((2,4,6-trimethoxyphenyl)imino)methyl)phenol (L2H), 2,4-di-tert-butyl-6-(((2,4-trimethoxyphenyl)imino)methyl)phenol) (L3H) derived from anilines bearing methoxy substituents have been employed in the preparation of alkylaluminum and zinc complexes. Molecular structure determinations reveal mono-chelate aluminum complexes of the type [Al(Ln)(Me)2] (L1, 1; L2, 2; L3, 3), and bis(chelate) complexes for zinc, namely [Zn(Ln)2] (L1, 5; L2, 6; L3, 7). All complexes have significant activity at 50 °C and higher activity at 100 °C for the ring-opening polymerization (ROP) of ε-caprolactone (ε-CL) with good control over the molar mass distribution (Mw/Mn < 2) and molecular weight. Complex 1 was found to be the most active catalyst, achieving 99% conversion within 18 h at 50 °C and giving polycaprolactone with high molecular weight; results are compared against aniline-derived (i.e., non-methoxy containing) complexes (4 and 8). Aluminum or zinc complexes derived from L1 exhibit higher activity as compared with complexes derived from L2 and L3. Complex 1 was also tested as an initiator for the copolymerization of ε-CL and glycolide (GL). The CL-GL copolymers have various microstructures depending on the feed ratio. The crosslinker 4,4′-bioxepane-7,7′-dione was used in the polymerization with ε-CL using 1, and well-defined cross-linked PCL was afforded of high molecular weight. Full article
(This article belongs to the Special Issue 10th Anniversary of Catalysts: Molecular Catalysis)
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19 pages, 5137 KiB  
Article
Propylene Polymerization and Deactivation Processes with Isoselective {Cp/Flu} Zirconocene Catalysts
by Xavier Desert, Thierry Roisnel, Vincent Dorcet, Katty Den Dauw, Aurélien Vantomme, Alexandre Welle, Jean-François Carpentier and Evgueni Kirillov
Catalysts 2021, 11(8), 959; https://doi.org/10.3390/catal11080959 - 10 Aug 2021
Cited by 1 | Viewed by 1879
Abstract
Industrially relevant single-site precatalysts used to produce isotactic polypropylene (iPP) include C2-symmetric {SBI} and C1-symmetric {Cp/Flu} complexes of group 4 metals. While the latter can produce iPPs with a higher degree of isotacticity, they also suffer from poor productivity [...] Read more.
Industrially relevant single-site precatalysts used to produce isotactic polypropylene (iPP) include C2-symmetric {SBI} and C1-symmetric {Cp/Flu} complexes of group 4 metals. While the latter can produce iPPs with a higher degree of isotacticity, they also suffer from poor productivity compared to their {SBI} counterparts. Several causes for this trend have been suggested—2,1-Regioinsertions are frequently pointed out, as they are suspected to drive the catalyst into a dormant state. While this event does not seem to significantly impact the productivity of {SBI} systems, the influence of these regioerror is poorly documented for isoselective {Cp/Flu} precatalysts. To address this issue, new Ph2X(Cp)(Flu) (Ph2X = Ph2C, FluC, Ph2Si) proligands (2ak) and some of the corresponding dichlorozirconocenes (3ah,k) were synthesized. These new compounds were characterized and tested in homogeneous propylene polymerization at 60 °C and the amounts of regioerrors in the resulting polymers were examined by 13C NMR spectroscopy. A possible correlation between poor productivity and a high number of regioerrors was investigated and is discussed. Furthermore, a C-H activation process in the bulky nBu3C substituent upon activation of 4c (the dimethylated analog of 3c) by B(C6F5)3 has been evidenced by NMR; DFT calculations support this C-H activation as a deactivation mechanism. Full article
(This article belongs to the Special Issue 10th Anniversary of Catalysts: Molecular Catalysis)
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13 pages, 1365 KiB  
Article
Cross-Coupling as a Key Step in the Synthesis and Structure Revision of the Natural Products Selagibenzophenones A and B
by Ringaile Lapinskaite, Štefan Malatinec, Miguel Mateus and Lukas Rycek
Catalysts 2021, 11(6), 708; https://doi.org/10.3390/catal11060708 - 04 Jun 2021
Cited by 5 | Viewed by 3580
Abstract
Selagibenzophenone A (1) and its isomer selagibenzophenone B (2) were recently described as natural products from Selaginella genus plants with PDE4 inhibitory activity. Herein, we report the first total syntheses of both compounds. By comparing spectroscopic data of the [...] Read more.
Selagibenzophenone A (1) and its isomer selagibenzophenone B (2) were recently described as natural products from Selaginella genus plants with PDE4 inhibitory activity. Herein, we report the first total syntheses of both compounds. By comparing spectroscopic data of the synthetic compounds with reported data for the isolated material, we demonstrate that the structure of one of the two natural products was incorrectly assigned, and that in fact isolated selagibenzophenone A and selagibenzophenone B are identical compounds. The synthetic strategy for both 1 and 2 is based on a cross-coupling reaction and on the addition of organometallic species to assemble the framework of the molecules. Identifying a suitable starting material with the correct substitution pattern is crucial because its pattern is reflected in that of the targeted compounds. These syntheses are finalized via global deprotection. Protecting the phenols as methoxy groups provides the possibility for partial control over the selectivity in the demethylation thanks to differences in the reactivity of the various methoxy groups. Our findings may help in future syntheses of derivatives of the biologically active natural product and in understanding the structure–activity relationship. Full article
(This article belongs to the Special Issue 10th Anniversary of Catalysts: Molecular Catalysis)
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21 pages, 1513 KiB  
Article
Design of Iridium N-Heterocyclic Carbene Amino Acid Catalysts for Asymmetric Transfer Hydrogenation of Aryl Ketones
by Chad M. Bernier and Joseph S. Merola
Catalysts 2021, 11(6), 671; https://doi.org/10.3390/catal11060671 - 24 May 2021
Cited by 6 | Viewed by 2758
Abstract
A series of chiral complexes of the form Ir(NHC)2(aa)(H)(X) (NHC = N-heterocyclic carbene, aa = chelated amino acid, X = halide) was synthesized by oxidative addition of α-amino acids to iridium(I) bis-NHC compounds and screened for asymmetric transfer hydrogenation of ketones. [...] Read more.
A series of chiral complexes of the form Ir(NHC)2(aa)(H)(X) (NHC = N-heterocyclic carbene, aa = chelated amino acid, X = halide) was synthesized by oxidative addition of α-amino acids to iridium(I) bis-NHC compounds and screened for asymmetric transfer hydrogenation of ketones. Following optimization of the reaction conditions, NHC, and amino acid ligands, high enantioselectivity was achieved when employing the Ir(IMe)2(l-Pro)(H)(I) catalyst (IMe = 1,3-dimethylimidazol-2-ylidene), which asymmetrically reduces a range of acetophenone derivatives in up to 95% enantiomeric excess. Full article
(This article belongs to the Special Issue 10th Anniversary of Catalysts: Molecular Catalysis)
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18 pages, 4334 KiB  
Article
Immobilization of Rh(I)-N-Xantphos and Fe(II)-C-Scorpionate onto Magnetic Nanoparticles: Reusable Catalytic System for Sequential Hydroformylation/Acetalization
by Fábio M. S. Rodrigues, Lucas D. Dias, Mário J. F. Calvete, Teresa M. R. Maria, Liane M. Rossi, Armando J. L. Pombeiro, Luísa M. D. R. S. Martins and Mariette M. Pereira
Catalysts 2021, 11(5), 608; https://doi.org/10.3390/catal11050608 - 10 May 2021
Cited by 4 | Viewed by 2278
Abstract
Two heterogeneous catalysts, MNP@SiO2-N-Xantphos/Rh(I) and MNP@SiO2-NH-C-scorpionate/Fe(II), were prepared by reaction of chloro-functionalized MNP@SiO2 with N-Xantphos and amino-functionalized MNP@SiO2 with iron(II)/C-allyl-scorpionate through nucleophilic substitution and hydroaminomethylation reactions, respectively. All catalysts were characterized using standard spectroscopic [...] Read more.
Two heterogeneous catalysts, MNP@SiO2-N-Xantphos/Rh(I) and MNP@SiO2-NH-C-scorpionate/Fe(II), were prepared by reaction of chloro-functionalized MNP@SiO2 with N-Xantphos and amino-functionalized MNP@SiO2 with iron(II)/C-allyl-scorpionate through nucleophilic substitution and hydroaminomethylation reactions, respectively. All catalysts were characterized using standard spectroscopic means, transmission electron microscopy (TEM), thermogravimetry (TG), and inductively coupled plasma optical emission spectrometry (ICP-OES). An active and highly selective one-pot hydroformylation/acetalization homogeneous system for the transformation of terminal and highly substituted olefins (including terpenes) onto ethyl acetals is described. A synergic effect of bimetallic Rh(I)/P and Fe(II)/C-scorpionate catalysts is disclosed for the first time. The further sequential use of the heterogeneous catalysts, MNP@SiO2-N-Xantphos/Rh(I) and MNP@SiO2-NH-C-scorpionate/Fe(II) in hydroformylation/acetalization reactions allows the direct transformation of olefin onto ethyl acetals, keeping the activity and selectivity. Both catalysts were easily recovered by magnetic separation and reused with negligible loss of activity/selectivity, after six reutilization cycles. Full article
(This article belongs to the Special Issue 10th Anniversary of Catalysts: Molecular Catalysis)
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Review

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48 pages, 20444 KiB  
Review
Catalytic Hydrofunctionalization Reactions of 1,3-Diynes
by Victorio Cadierno
Catalysts 2022, 12(1), 89; https://doi.org/10.3390/catal12010089 - 13 Jan 2022
Cited by 4 | Viewed by 2855
Abstract
Metal-catalyzed hydrofunctionalization reactions of alkynes, i.e., the addition of Y–H units (Y = heteroatom or carbon) across the carbon–carbon triple bond, have attracted enormous attention for decades since they allow the straightforward and atom-economic access to a wide variety of functionalized olefins and, [...] Read more.
Metal-catalyzed hydrofunctionalization reactions of alkynes, i.e., the addition of Y–H units (Y = heteroatom or carbon) across the carbon–carbon triple bond, have attracted enormous attention for decades since they allow the straightforward and atom-economic access to a wide variety of functionalized olefins and, in its intramolecular version, to relevant heterocyclic and carbocyclic compounds. Despite conjugated 1,3-diynes being considered key building blocks in synthetic organic chemistry, this particular class of alkynes has been much less employed in hydrofunctionalization reactions when compared to terminal or internal monoynes. The presence of two C≡C bonds in conjugated 1,3-diynes adds to the classical regio- and stereocontrol issues associated with the alkyne hydrofunctionalization processes’ other problems, such as the possibility to undergo 1,2-, 3,4-, or 1,4-monoadditions as well as double addition reactions, thus increasing the number of potential products that can be formed. In this review article, metal-catalyzed hydrofunctionalization reactions of these challenging substrates are comprehensively discussed. Full article
(This article belongs to the Special Issue 10th Anniversary of Catalysts: Molecular Catalysis)
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34 pages, 10495 KiB  
Review
Oxidative Degradation of Pharmaceuticals: The Role of Tetrapyrrole-Based Catalysts
by Giusi Piccirillo, Rafael T. Aroso, Fábio M. S. Rodrigues, Rui M. B. Carrilho, Sara M. A. Pinto, Mário J. F. Calvete and Mariette M. Pereira
Catalysts 2021, 11(11), 1335; https://doi.org/10.3390/catal11111335 - 04 Nov 2021
Cited by 17 | Viewed by 2782
Abstract
Nowadays, society’s widespread consumption of pharmaceutical drugs and the consequent accumulation of such compounds or their metabolites in effluents requires the development of efficient strategies and systems that lead to their effective degradation. This can be done through oxidative processes, in which tetrapyrrolic [...] Read more.
Nowadays, society’s widespread consumption of pharmaceutical drugs and the consequent accumulation of such compounds or their metabolites in effluents requires the development of efficient strategies and systems that lead to their effective degradation. This can be done through oxidative processes, in which tetrapyrrolic macrocycles (porphyrins, phthalocyanines) deserve special attention since they are among the most promising degradation catalysts. This paper presents a review of the literature over the past ten years on the major advances made in the development of oxidation processes of pharmaceuticals in aqueous solutions using tetrapyrrole-based catalysts. The review presents a brief discussion of the mechanisms involved in these oxidative processes and is organized by the degradation of families of pharmaceutical compounds, namely antibiotics, analgesics and neurological drugs, among others. For each family, a critical analysis and discussion of the fundamental roles of tetrapyrrolic macrocycles are presented, regarding both photochemical degradative processes and direct oxidative chemical degradation. Full article
(This article belongs to the Special Issue 10th Anniversary of Catalysts: Molecular Catalysis)
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Other

11 pages, 2596 KiB  
Perspective
α-Diimine Ni-Catalyzed Ethylene Polymerizations: On the Role of Nickel(I) Intermediates
by Igor E. Soshnikov, Nina V. Semikolenova, Konstantin P. Bryliakov and Evgenii P. Talsi
Catalysts 2021, 11(11), 1386; https://doi.org/10.3390/catal11111386 - 17 Nov 2021
Cited by 7 | Viewed by 2239
Abstract
Nickel(II) complexes with bidentate N,N-α-diimine ligands constitute a broad class of promising catalysts for the synthesis of branched polyethylenes via ethylene homopolymerization. Despite extensive studies devoted to the rational design of new Ni(II) α-diimines with desired catalytic properties, the polymerization [...] Read more.
Nickel(II) complexes with bidentate N,N-α-diimine ligands constitute a broad class of promising catalysts for the synthesis of branched polyethylenes via ethylene homopolymerization. Despite extensive studies devoted to the rational design of new Ni(II) α-diimines with desired catalytic properties, the polymerization mechanism has not been fully rationalized. In contrast to the well-characterized cationic Ni(II) active sites of ethylene polymerization and their precursors, the structure and role of Ni(I) species in the polymerization process continues to be a “black box”. This perspective discusses recent advances in the understanding of the nature and role of monovalent nickel complexes formed in Ni(II) α-diimine-based ethylene polymerization catalyst systems. Full article
(This article belongs to the Special Issue 10th Anniversary of Catalysts: Molecular Catalysis)
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