Special Issue "Homogeneous Catalysis and Mechanisms in Water and Biphasic Media"

A special issue of Catalysts (ISSN 2073-4344). This special issue belongs to the section "Catalytic Materials".

Deadline for manuscript submissions: closed (31 December 2017).

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special Issue Editor

Guest Editor
Dr. Luca Gonsalvi

Institute of Chemistry of Organometallic Compounds, National Research Council of Italy (ICCOM-CNR), Via Madonna del Piano 10, 50019 Sesto Fiorentino (Florence), Italy
Website | E-Mail
Phone: +39 055 5225251
Fax: +39 055 5225203
Interests: organometallics and catalysis in water and biphasic systems; CO2 activation and utilization processes; hydrogen activation, production and storage by organometallics; homogeneous catalysis; catalytic mechanisms

Special Issue Information

Dear Colleagues,

After its discovery in the early 1980s and successful application on an industrial scale (SHOP and Ruhrchemie/Rhône-Poulenc processes), water phase and biphasic catalysis have been the subject of fundamental studies in a relatively limited number of research laboratories around the world, almost at a curiosity level. During the last 15 years, however, this topic has witnessed a true renaissance, mainly due to the increased attention of industry and academia to more environmentally friendly processes.  Water is the green solvent par excellence, and a great deal of research has been carried out to convey the properties of known transition metal catalysts to their water-soluble analogs, maintaining high activities and selectivities. The keys to success have been, among others, the discovery of synthetic pathways to novel molecular and nanosized metal-based catalysts, new mechanistic insights in the role of water as non-innocent solvent, the identification of reaction pathways by experimental and theoretical methods, and the application of novel concepts for phase transfer agents in biphasic catalysis.

In this Special Issue, the latest achievements in synthetic ligand and catalyst modifications, applications to selected substrate activation related to bulk chemicals, commodities and energy vectors, such as hydrogen, will be highlighted, together with recent mechanistic studies, unconventional approaches, and engineering solutions.

Dr. Luca Gonsalvi
Guest Editor

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Keywords

  • Water phase catalysis

  • Catalysis in biphasic systems

  • Mechanistic studies

  • Theoretical studies

  • C-Element bond activation in water

  • Water soluble organometallic compounds

  • Water soluble ligands and applications

  • Small molecules activation in water

  • Green chemistry

Published Papers (10 papers)

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Editorial

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Open AccessEditorial
Homogeneous Catalysis and Mechanisms in Water and Biphasic Media
Catalysts 2018, 8(11), 543; https://doi.org/10.3390/catal8110543
Received: 7 November 2018 / Revised: 10 November 2018 / Accepted: 12 November 2018 / Published: 14 November 2018
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Abstract
After its discovery in the early 1980s and successful application on an industrial scale (Ruhrchemie/Rhone-Poulenc process) [...] Full article

Research

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Open AccessArticle
Ruthenium(II)-Arene Complexes of the Water-Soluble Ligand CAP as Catalysts for Homogeneous Transfer Hydrogenations in Aqueous Phase
Catalysts 2018, 8(2), 88; https://doi.org/10.3390/catal8020088
Received: 29 December 2017 / Revised: 14 February 2018 / Accepted: 15 February 2018 / Published: 22 February 2018
Cited by 5 | PDF Full-text (5790 KB) | HTML Full-text | XML Full-text
Abstract
The neutral Ru(II) complex κP-[RuCl26-p-cymene)(CAP)] (1), and the two ionic complexes κP-[RuCl(η6-p-cymene)(MeCN)(CAP)]PF6 (2) and κP-[RuCl(η6-p-cymene)(CAP)2]PF6 [...] Read more.
The neutral Ru(II) complex κP-[RuCl26-p-cymene)(CAP)] (1), and the two ionic complexes κP-[RuCl(η6-p-cymene)(MeCN)(CAP)]PF6 (2) and κP-[RuCl(η6-p-cymene)(CAP)2]PF6 (3), containing the water-soluble phosphine 1,4,7-triaza-9-phosphatricyclo[5.3.2.1]tridecane (CAP), were tested as catalysts for homogeneous hydrogenation of benzylidene acetone, selectively producing the saturated ketone as product. The catalytic tests were carried out in aqueous phase under transfer hydrogenation conditions, at mild temperatures using sodium formate as hydrogen source. Complex 3, which showed the highest stability under the reaction conditions applied, was also tested for C=N bond reduction from selected cyclic imines. Preliminary NMR studies run under pseudo-catalytic conditions starting from 3 showed the formation of κP-[RuH(η6-p-cymene)(CAP)2]PF6 (4) as the pivotal species in catalysis. Full article
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Open AccessArticle
Effect of Iminodiacetic Acid-Modified Nieuwland Catalyst on the Acetylene Dimerization Reaction
Catalysts 2017, 7(12), 394; https://doi.org/10.3390/catal7120394
Received: 19 November 2017 / Revised: 16 December 2017 / Accepted: 16 December 2017 / Published: 19 December 2017
Cited by 4 | PDF Full-text (3996 KB) | HTML Full-text | XML Full-text
Abstract
The iminodiacetic acid-modified Nieuwland catalyst not only improves the conversion of acetylene but also increases the selectivity of monovinylacetylene (MVA). A catalyst system containing 4.5% iminodiacetic acid exhibited excellent performance, and the yield of MVA was maintained at 32% after 24 h, producing [...] Read more.
The iminodiacetic acid-modified Nieuwland catalyst not only improves the conversion of acetylene but also increases the selectivity of monovinylacetylene (MVA). A catalyst system containing 4.5% iminodiacetic acid exhibited excellent performance, and the yield of MVA was maintained at 32% after 24 h, producing an increase in the yield by 12% relative to the Nieuwland catalyst system. Based on a variety of characterization methods analysis of the crystal precipitated from the catalyst solution, it can be inferred that the outstanding performance and lifetime of the catalyst system was due to the presence of iminodiacetic acid, which increases the electron density of Cu+ and adjusts the acidity of the catalytic solution. Full article
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Open AccessArticle
Catalytic Activities of Ribozymes and DNAzymes in Water and Mixed Aqueous Media
Catalysts 2017, 7(12), 355; https://doi.org/10.3390/catal7120355
Received: 1 November 2017 / Revised: 13 November 2017 / Accepted: 20 November 2017 / Published: 23 November 2017
Cited by 4 | PDF Full-text (940 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Catalytic nucleic acids are regarded as potential therapeutic agents and biosensors. The catalytic activities of nucleic acid enzymes are usually investigated in dilute aqueous solutions, although the physical properties of the reaction environment inside living cells and that in the area proximal to [...] Read more.
Catalytic nucleic acids are regarded as potential therapeutic agents and biosensors. The catalytic activities of nucleic acid enzymes are usually investigated in dilute aqueous solutions, although the physical properties of the reaction environment inside living cells and that in the area proximal to the surface of biosensors in which they operate are quite different from those of pure water. The effect of the molecular environment is also an important focus of research aimed at improving and expanding nucleic acid function by addition of organic solvents to aqueous solutions. In this study, the catalytic activities of RNA and DNA enzymes (hammerhead ribozyme, 17E DNAzyme, R3C ribozyme, and 9DB1 DNAzyme) were investigated using 21 different mixed aqueous solutions comprising organic compounds. Kinetic measurements indicated that these enzymes can display enhanced catalytic activity in mixed solutions with respect to the solution containing no organic additives. Correlation analyses revealed that the turnover rate of the reaction catalyzed by hammerhead ribozyme increased in a medium with a lower dielectric constant than water, and the turnover rate of the reaction catalyzed by 17E DNAzyme increased in conditions that increased the strength of DNA interactions. On the other hand, R3C ribozyme and 9DB1 DNAzyme displayed no significant turnover activity, but their single-turnover rates increased in many mixed solutions. Our data provide insight into the activity of catalytic nucleic acids under various conditions that are applicable to the medical and technology fields, such as in living cells and in biosensors. Full article
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Open AccessFeature PaperArticle
Dehydrogenation of Formic Acid over a Homogeneous Ru-TPPTS Catalyst: Unwanted CO Production and Its Successful Removal by PROX
Catalysts 2017, 7(11), 348; https://doi.org/10.3390/catal7110348
Received: 26 October 2017 / Revised: 13 November 2017 / Accepted: 13 November 2017 / Published: 20 November 2017
Cited by 6 | PDF Full-text (2286 KB) | HTML Full-text | XML Full-text
Abstract
Formic acid (FA) is considered as a potential durable energy carrier. It contains ~4.4 wt % of hydrogen (or 53 g/L) which can be catalytically released and converted to electricity using a proton exchange membrane (PEM) fuel cell. Although various catalysts have been [...] Read more.
Formic acid (FA) is considered as a potential durable energy carrier. It contains ~4.4 wt % of hydrogen (or 53 g/L) which can be catalytically released and converted to electricity using a proton exchange membrane (PEM) fuel cell. Although various catalysts have been reported to be very selective towards FA dehydrogenation (resulting in H2 and CO2), a side-production of CO and H2O (FA dehydration) should also be considered, because most PEM hydrogen fuel cells are poisoned by CO. In this research, a highly active aqueous catalytic system containing Ru(III) chloride and meta-trisulfonated triphenylphosphine (mTPPTS) as a ligand was applied for FA dehydrogenation in a continuous mode. CO concentration (8–70 ppm) in the resulting H2 + CO2 gas stream was measured using a wide range of reactor operating conditions. The CO concentration was found to be independent on the reactor temperature but increased with increasing FA feed. It was concluded that unwanted CO concentration in the H2 + CO2 gas stream was dependent on the current FA concentration in the reactor which was in turn dependent on the reaction design. Next, preferential oxidation (PROX) on a Pt/Al2O3 catalyst was applied to remove CO traces from the H2 + CO2 stream. It was demonstrated that CO concentration in the stream could be reduced to a level tolerable for PEM fuel cells (~3 ppm). Full article
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Open AccessArticle
Efficient Degradation of Aqueous Carbamazepine by Bismuth Oxybromide-Activated Peroxide Oxidation
Catalysts 2017, 7(11), 315; https://doi.org/10.3390/catal7110315
Received: 28 September 2017 / Revised: 11 October 2017 / Accepted: 18 October 2017 / Published: 26 October 2017
Cited by 4 | PDF Full-text (7916 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Bismuth oxyhalide, usually employed as a photocatalyst, has not been tested as an activator of peroxide for water purification. This work explores the potential application of bismuth oxyhalide (BiOX, X = Cl, Br, I)-activated peroxide (H2O2; peroxymonosulfate (PMS) and [...] Read more.
Bismuth oxyhalide, usually employed as a photocatalyst, has not been tested as an activator of peroxide for water purification. This work explores the potential application of bismuth oxyhalide (BiOX, X = Cl, Br, I)-activated peroxide (H2O2; peroxymonosulfate (PMS) and peroxydisulfate) systems for the degradation of carbamazepine (CBZ) in water destined for drinking water. BiOBr showed the highest activity toward the peroxides investigated, especially toward PMS. The most efficient combination, BiOBr/PMS, was selected to further research predominant species responsible for CBZ degradation and toxicity of transformation products. With repeated use of BiOBr, low bismuth-leaching and subtle changes in crystallinity and activity were observed. CBZ degradation was primarily (67.3%) attributable to attack by sulfate radical. Toxicity test and identification of the oxidation products indicated some toxic intermediates may be produced. A possible degradation pathway is proposed. Besides substitution of the hydroxyl groups on the surface of the catalyst particles, PMS’s complexation with the lattice Bi(III) through ion exchange with interlayer bromide ion was involved in the decomposition of PMS. The Bi(III)−Bi(V)−Bi(III) redox cycle contributed to the efficient generation of sulfate radicals from the PMS. Our findings provide a simple and efficient process to produce powerful radicals from PMS for refractory pollutant removal. Full article
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Open AccessArticle
Chitosan Aerogel Catalyzed Asymmetric Aldol Reaction in Water: Highly Enantioselective Construction of 3-Substituted-3-hydroxy-2-oxindoles
Catalysts 2016, 6(12), 186; https://doi.org/10.3390/catal6120186
Received: 3 October 2016 / Revised: 10 November 2016 / Accepted: 21 November 2016 / Published: 28 November 2016
Cited by 10 | PDF Full-text (4797 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
A chitosan aerogel catalyzed asymmetric aldol reaction of ketones with isatins in the presence of water is described. This protocol was found to be environmentally benign, because it proceeds smoothly in water and the corresponding aldol products were obtained in excellent yields with [...] Read more.
A chitosan aerogel catalyzed asymmetric aldol reaction of ketones with isatins in the presence of water is described. This protocol was found to be environmentally benign, because it proceeds smoothly in water and the corresponding aldol products were obtained in excellent yields with good enantioselectivities. Full article
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Review

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Open AccessReview
Ultrasonic Monitoring of Biocatalysis in Solutions and Complex Dispersions
Catalysts 2017, 7(11), 336; https://doi.org/10.3390/catal7110336
Received: 19 September 2017 / Revised: 26 October 2017 / Accepted: 26 October 2017 / Published: 15 November 2017
Cited by 5 | PDF Full-text (8212 KB) | HTML Full-text | XML Full-text
Abstract
The rapidly growing field of chemical catalysis is dependent on analytical methods for non-destructive real-time monitoring of chemical reactions in complex systems such as emulsions, suspensions and gels, where most analytical techniques are limited in their applicability, especially if the media is opaque, [...] Read more.
The rapidly growing field of chemical catalysis is dependent on analytical methods for non-destructive real-time monitoring of chemical reactions in complex systems such as emulsions, suspensions and gels, where most analytical techniques are limited in their applicability, especially if the media is opaque, or if the reactants/products do not possess optical activity. High-resolution ultrasonic spectroscopy is one of the novel technologies based on measurements of parameters of ultrasonic waves propagating through analyzed samples, which can be utilized for real-time non-invasive monitoring of chemical reactions. It does not require optical transparency, optical markers and is applicable for monitoring of reactions in continuous media and in micro/nano bioreactors (e.g., nanodroplets of microemulsions). The technology enables measurements of concentrations of substrates and products over the whole course of reaction, analysis of time profiles of the degree of polymerization and molar mass of polymers and oligomers, evolutions of reaction rates, evaluation of kinetic mechanisms, measurements of kinetic and equilibrium constants and reaction Gibbs energy. It also provides tools for assessments of various aspects of performance of catalysts/enzymes including inhibition effects, reversible and irreversible thermal deactivation. In addition, ultrasonic scattering effects in dispersions allow real-time monitoring of structural changes in the medium accompanying chemical reactions. Full article
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Open AccessFeature PaperReview
Metal-Catalyzed Intra- and Intermolecular Addition of Carboxylic Acids to Alkynes in Aqueous Media: A Review
Catalysts 2017, 7(11), 328; https://doi.org/10.3390/catal7110328
Received: 19 October 2017 / Revised: 1 November 2017 / Accepted: 2 November 2017 / Published: 6 November 2017
Cited by 4 | PDF Full-text (6436 KB) | HTML Full-text | XML Full-text
Abstract
The metal-catalyzed addition of carboxylic acids to alkynes is a very effective tool for the synthesis of carboxylate-functionalized olefinic compounds in an atom-economical manner. Thus, a large variety of synthetically useful lactones and enol-esters can be accessed through the intra- or intermolecular versions [...] Read more.
The metal-catalyzed addition of carboxylic acids to alkynes is a very effective tool for the synthesis of carboxylate-functionalized olefinic compounds in an atom-economical manner. Thus, a large variety of synthetically useful lactones and enol-esters can be accessed through the intra- or intermolecular versions of this process. In order to reduce the environmental impact of these reactions, considerable efforts have been devoted in recent years to the development of catalytic systems able to operate in aqueous media, which represent a real challenge taking into account the tendency of alkynes to undergo hydration in the presence of transition metals. Despite this, different Pd, Pt, Au, Cu and Ru catalysts capable of promoting the intra- and intermolecular addition of carboxylic acids to alkynes in a selective manner in aqueous environments have appeared in the literature. In this review article, an overview of this chemistry is provided. The synthesis of β-oxo esters by catalytic addition of carboxylic acids to terminal propargylic alcohols in water is also discussed. Full article
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Open AccessReview
Unconventional Approaches Involving Cyclodextrin-Based, Self-Assembly-Driven Processes for the Conversion of Organic Substrates in Aqueous Biphasic Catalysis
Catalysts 2017, 7(6), 173; https://doi.org/10.3390/catal7060173
Received: 2 May 2017 / Revised: 26 May 2017 / Accepted: 26 May 2017 / Published: 2 June 2017
Cited by 13 | PDF Full-text (3882 KB) | HTML Full-text | XML Full-text
Abstract
Aqueous biphasic catalysis is a convenient approach to convert organic, partially soluble molecules in water. However, converting more hydrophobic substrates is much more challenging as their solubility in water is extremely low. During the past ten years, substantial progress has been made towards [...] Read more.
Aqueous biphasic catalysis is a convenient approach to convert organic, partially soluble molecules in water. However, converting more hydrophobic substrates is much more challenging as their solubility in water is extremely low. During the past ten years, substantial progress has been made towards improving the contact between hydrophobic substrates and a hydrophilic transition-metal catalyst. The main cutting-edge approaches developed in the field by using cyclodextrins as a supramolecular tool will be discussed and compared in this short review. Full article
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