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159. Capture agents, conversion mechanisms, biotransformations and biomimetics: general discussion

Author

Remiezowicz, Eryk, primary, Spooren, Jeroen, additional, Bay, Elizabeth, additional, Cowan, Alexander, additional, Ingram, Ian, additional, Abrantes, Pedro, additional, Nunes da Ponte, Manuel, additional, North, Michael, additional, Albo, Jonathan, additional, Styring, Peter, additional, Priestnall, Michael, additional, Lamb, Katie, additional, Aresta, Michele, additional, Quadrelli, Elsje Alessandra, additional, Heyn, Richard, additional, Bardow, André, additional, Webb, William, additional, Silva, Renata, additional, Alonso-Moreno, Carlos, additional, Janaky, Csaba, additional, Maitland, Geoffrey, additional, Vaidyanathan, Seetharaman, additional, V. S. M. Carrera, Gonçalo, additional, Reed, Daniel, additional, Vanbroekhoven, Karolien, additional, Yavuz, Cafer Tayyar, additional, Pant, Deepak, additional, and Hollingsworth, Nathan, additional

Published
2015
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160. CO2reduction reactions: general discussion

Author

North, Michael, primary, Abrantes, Pedro, additional, Remiezowicz, Eryk, additional, Bardow, André, additional, Dodson, Jennifer, additional, Manning, Troy, additional, Albo, Jonathan, additional, Reed, Daniel, additional, Harris, Derek, additional, Ingram, Ian, additional, Cowan, Alexander, additional, Moss, Matthew, additional, Carrera, Gonçalo V. S. M., additional, Foote, Alexander, additional, Fraga, Eric, additional, Styring, Peter, additional, Bogaerts, Annemie, additional, Centi, Gabriele, additional, Navarrete, Alexander, additional, Comerford, James, additional, Dowson, George, additional, Coogan, Anthony, additional, Butterworth, Thomas, additional, Lamb, Katie, additional, Aresta, Michele, additional, Janaky, Csaba, additional, Heyn, Richard, additional, Webb, William, additional, van Rooij, Gerard, additional, Meine, Niklas, additional, Meynen, Vera, additional, Michez, Roman, additional, Churina, Dina, additional, Dossumov, Kusman, additional, Du, Xian, additional, Spooren, Jeroen, additional, Herskowitz, Moti, additional, Michiels, Koen, additional, and Capacchione, Carmine, additional

Published
2015
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162. Atom efficiency in small molecule and macromolecule synthesis: general discussion

Author

Buchard, Antoine, primary, North, Michael, additional, Kozak, Christopher, additional, Remiezowicz, Eryk, additional, Abrantes, Pedro, additional, Bardow, André, additional, Dodson, Jennifer, additional, Williams, Charlotte, additional, Albo, Jonathan, additional, Ingram, Ian, additional, V. S. M. Carrera, Gonçalo, additional, Styring, Peter, additional, Poliakoff, Martyn, additional, Lamb, Katie, additional, Quadrelli, Elsje Alessandra, additional, MacDowell, Niall, additional, Dowson, George, additional, Aresta, Michele, additional, Heyn, Richard, additional, Castro-Osma, José A., additional, Webb, William, additional, Silva, Renata, additional, Marciniak, Aryane, additional, Jones, Christopher, additional, Yavuz, Cafer Tayyar, additional, Capacchione, Carmine, additional, Coogan, Anthony, additional, and Priestnall, Michael, additional

Published
2015
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163. Wider Impacts: general discussion

Author

Jones, Christopher, primary, Armstrong, Katy, additional, Ingram, Ian, additional, Bay, Elizabeth, additional, Dodson, Jennifer, additional, Abrantes, Pedro, additional, North, Michael, additional, Styring, Peter, additional, MacDowell, Niall, additional, Churina, Dina, additional, Lamb, Katie, additional, Aresta, Michele, additional, Dowson, George, additional, Heyn, Richard, additional, Quadrelli, Elsje Alessandra, additional, Silva, Renata, additional, Marciniak, Aryane, additional, Meine, Niklas, additional, Dossumov, Kusman, additional, Navarrete, Alexander, additional, Bardow, André, additional, Coogan, Anthony, additional, and Fraga, Eric, additional

Published
2015
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164. BackMatter.

Author

Aresta, Michele, Dibenedetto, Angela, and Quaranta, Eugenio

Published
2016

165. FrontMatter.

Author

Aresta, Michele, Dibenedetto, Angela, and Quaranta, Eugenio

Published
2016

166. Synthesis and Characterization of Fe0(2,2′-bipyridine) (2-aminoethyl-pyridine) and its Reaction with Dihydrogen.

Author

Dibenedetto, Angela, Roth, Cristina E., Aresta, Michele, and Pápai, Imre

Subjects
IRON, DIHYDROGEN bonding, HYDROGENATION kinetics, ADDITION reactions, CHEMICAL research
Abstract

Fe0(bpy)(pyea) ( 2; bpy=2,2′-bipyridine, pyea=2-aminoethyl-pyridine), a 16-electron species, was synthesized by reduction of FeCl2(bpy)(pyea) ( 1) using Na-strips. It is a diamagnetic low-melting solid (m.p. 295 K) stable under N2 and easily decomposed by radiations even at low temperature. It was fully characterized by elemental analyses and multinuclear NMR. Complex 2 acts as an active hydrogenation catalyst, but has a very short lifetime. In fact, it reacts with H2 (0.1-1 MPa) at room temperature in toluene and affords in a few minutes a new Fe0 complex characterized as Fe0(bpy)(η6-picoline) ( 3), inactive to hydrogenation. Picoline is derived from the sp3-sp3 C−C bond cleavage of the aminoethyl arm of the pyea ligand. The rapid evolution of the putative intermediate FeH2(bpy)(pyea) ( 4) has not allowed the isolation such Fe-hydrido species. The interaction of H2 with 2 has been studied by DFT, which has allowed to demonstrate that 3 is lower in energy than 2+H2, justifying the fact that the intermediate dihydride was not isolated. Interestingly, 3 was also obtained by reaction of 1 with NaBH4 or with glycerol-KOH. Complex 2 is one of the rare examples of Fe0 complex stabilized by a set of only N-donor atoms. The reaction with glycerol confirms the potential role of Fe in catalytic hydrogenation reactions using bio-glycerol as a H-source. [ABSTRACT FROM AUTHOR]

Published
2017
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180. Organic Carbonates: Efficient Extraction Solvents for the Synthesis of HMF in Aqueous Media with Cerium Phosphates as Catalysts.

Author

Dibenedetto, Angela, Aresta, Michele, di Bitonto, Luigi, and Pastore, Carlo

Subjects
CARBONATES, EXTRACTION (Chemistry), SOLVENTS, CHEMICAL synthesis, CATALYSIS research
Abstract

We describe a process for the selective conversion of C6-polyols into 5-hydroxymethylfurfural (5-HMF) in biphasic systems of organic carbonate/water (OC/W), with cerium(IV) phosphates as catalysts. Different reaction parameters such as the OC/W ratio, catalyst loading, reaction time, and temperature, were investigated for the dehydration of fructose. Under the best reaction conditions, a yield of 67.7 % with a selectivity of 93.2 % was achieved at 423 K after 6 h of reaction using [(Ce(PO4)1.5(H2O)(H3O)0.5(H2O)0.5)] as the catalyst. A maximum yield of 70 % with the same selectivity was achieved after 12 h. At the end of the reaction, the catalyst was removed by centrifugation, the organic phase was separated from water and evaporated in vacuo (with solvent recovery), and solid 5-HMF was isolated (purity >99 %). The recovery and reuse of the catalyst and the relationship between the structure of the OC and the efficiency of the extraction are discussed. The OC/W system influences the lifetime of the catalysts positively compared to only water. [ABSTRACT FROM AUTHOR]

Published
2016
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192. Synthesis and X-ray characterization of [RhCl(C2H4)(PiPr3)]2. Multinuclear NMR and DFT investigation of its solid-state and solution reaction with dihydrogen. Ethene and propene hydrogenation by the solid Rh-hydrides

Author

Angelini, Antonella, primary, Aresta, Michele, additional, Dibenedetto, Angela, additional, Pastore, Carlo, additional, Quaranta, Eugenio, additional, Chierotti, Michele R., additional, Gobetto, Roberto, additional, Pápai, Imre, additional, Graiff, Claudia, additional, and Tiripicchio, Antonio, additional

Published
2009
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197. Synthesis and Characterization of Chloro- and Alkyliron Complexes with N-Donor Ligands and Their Reactivity towards CO2.

Author

Roth, Cristina E., Dibenedetto, Angela, and Aresta, Michele

Subjects
IRON compounds, METAL complexes, LIGANDS (Chemistry), REACTIVITY (Chemistry), ETHYLAMINES, CARBON dioxide
Abstract

New iron(II) compounds with N-donor ligands [2,2′-bipyridine (bpy) and 2-(2-pyridyl)ethylamine (pyea)] were synthesized, and their reactivity with carbon dioxide was investigated. The reactions of Fe(bpy)(pyea)Cl2 ( 1) with CO2 (0.9 MPa) afforded the carbamato derivative Fe(bpy)(pyea-CO2)Cl2 ( 2), which reacted with CH3Li to afford the monomethyl carbamato complex Fe(bpy)(pyea-CO2)ClCH3 ( 3), an example of a carbamato species that is stable over a carboxylato moiety. Fe[(bpy)(pyea)](CH3)2 ( 4), obtained by reaction of 1 with CH3Li, was treated with CO2 (0.3-0.5 MPa) to afford the dicarboxylato species Fe[(bpy)(pyea)](O2CCH3)2 ( 5), which provides evidence of normal double insertion of CO2 into the Fe-C bond. The reaction of 5 with HCl afforded 1 and CH3-CO2H, which confirmed the mode of bonding of the -O2CCH3 moiety to the Fe center. To verify the preference of insertion of CO2 into the Fe-C or the Fe-N bond, 1 was treated with MeLi (1 equiv.), and Fe(bpy)(pyea)Cl(CH3) ( 6) was isolated as a low-melting solid. The latter was treated with CO2 (0.5 MPa), and the product of insertion into the Fe-CH3 bond was observed as the only carboxylate ( 7). The faster insertion into the Fe-CH3 bond is explained by the fact that the N donor is quaternarized upon interaction with the metal center and has no free electrons available to interact with the C acceptor of the cumulene molecule; thus, more-forcing conditions (0.9 MPa) are required for the insertion to occur. [ABSTRACT FROM AUTHOR]

Published
2015
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198. Solar energy utilization in the direct photocarboxylation of 2,3-dihydrofuran using CO2.

Author

Aresta, Michele, Dibenedetto, Angela, Baran, Tomasz, Wojtyła, Szymon, and Macyk, Wojciech

Abstract

The conversion of CO2 into high energy products (fuels) and the direct carboxylation of C–H bonds require a high energy input. Energy cannot be derived from fossil carbon, in this case. Solar energy can be used instead, with a low environmental impact and good profit. We have studied the use of white light or solar energy in the photoreduction of CO2 and in photocarboxylation reactions, using different semiconductors modified at their surface. Two examples of reduction of CO2 to methanol and CO will be shortly discussed, and two cases of carboxylation of organic substrates. The case of carboxylation of 2,3-dihydrofuran will be discussed in detail. [ABSTRACT FROM AUTHOR]

Published
2015
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199. Reaction Mechanisms in the Direct Carboxylation of Alcohols for the Synthesis of Acyclic Carbonates.

Author

Aresta, Michele, Dibenedetto, Angela, Angelini, Antonella, and Pápai, Imre

Subjects
*CARBOXYLATION, *ALCOHOL, *CARBONATE synthesis, *ACID-base chemistry, *CHEMICAL reactions
Abstract

Dialkylcarbonates, (RO)CO, can be prepared from alcohols and CO. Such reaction is clean (water is the co-product) but thermodynamically disfavored. In principle, the reaction mechanism of formation of carbonates requires the acid-base activation of alcohols. Existing data support that the first step is the formation of the alkoxo group RO that reacts with CO to give the hemicarbonate moiety ROC(O)O. The latter converts into the relevant carbonate (RO)CO following different pathways depending on the catalyst used. DFT calculations have been used in a few cases to support the reaction mechanism. Transition states relevant to various mechanistic scenarios have been identified. The results indicated that the relative energies of these transition states depend on the nature of the alkyl group and the molecularity of the reactive step. Organic catalysts, homogeneous-, heterogenized- and heterogeneous-metal systems are discussed in this paper and the known relevant mechanisms compared. Water represents a serious limitation to equilibrium shift to the right and can affect the catalysts. Techniques used to remove water are also discussed. [ABSTRACT FROM AUTHOR]

Published
2015
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200. The reaction mechanism in the ethanolysis of urea with transition metal-based catalysts: DFT calculations and experiments.

Author

Dibenedetto, Angela, Angelini, Antonella, Fasciano, Stefania, Pàpai, Imre, Curulla-Ferré, Daniel, and Aresta, Michele

Subjects
UREA, METAL catalysts, DENSITY functional theory, METHANOLYSIS, CARBONATES, CARBON dioxide, ZINC oxide, TRANSITION metals
Abstract

Alcoholysis of urea is an attractive methodology for the synthesis of organic acyclic carbonates. It has low environmental impact and represents an indirect way of using CO 2 . ZnO, known to have interesting performances, is reported in the literature to behave as a homogeneous catalyst in the form of Zn(NCO) 2 (NH 3 ) 2 in the methanolyis of urea. In this paper, theoretical and experimental studies are described aimed at shading light on the reaction mechanism of ethanol with urea under transition-metal ( T M ) catalysis. The reaction of ethanolysis of urea proceeds in two steps: i) formation of ethylcarbamate (EC) also in absence of catalysts; ii) co-ordination of EC, via the carbonylic group, to a T M centre and alcoholysis to afford diethylcarbonate (DEC). The adduct T M -EC has been isolated using several T M s (Zn, Sc, La) and characterized. It has been shown to react with ethanol to afford DEC. The energetics (free Gibbs energy) of the non-catalyzed and catalyzed ethanolysis of EC have been compared, highlighting the role of the T M as catalyst. The same reaction mechanism has been shown to hold for methanol, also if the energy of the TSs differs from EtOH. The reaction mechanism demonstrated in this paper for the ethanol(methanol)–urea reaction is dissimilar from that reported in the literature for the methanol–urea system, most probably due to both: i) higher level of DFT calculations used in this work that most carefully reveals the energetics of the TSs, and ii) use of Gibbs Free Energy instead of Enthalpy used by other authors. [ABSTRACT FROM AUTHOR]

Published
2014
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