Search results for "Cyclic Carbonate"
showing 10 items of 18 documents
Supported Polyhedral Oligomeric Silsesquioxane-Based (POSS) Materials as Highly Active Organocatalysts for the Conversion of CO2
2018
Very high turnover numbers (TON) and productivity values up to 7875 and 740 respectively have been obtained for the conversion of CO2 into cyclic carbonates by using hybrid materials based on imidazolium modified polyhedral oligomeric silsesquioxanes (POSS-Imi) grafted on amorphous silica (SiO2) and mesostructured SBA-15. The heterogeneous organocatalysts were easily prepared via a straightforward synthetic procedure allowing to generate high local concentration spots of imidazolium active sites surrounding the POSS core. This synthetic procedure is also a promising approach for the design of a wide library of hybrid functional materials. The materials do not possess other co-catalytic spec…
Carbon nanotube supported aluminum porphyrin-imidazolium bromide crosslinked copolymer
2022
The increased awareness of the catastrophic consequences caused by the accumulation of greenhouse gases into the atmosphere has generated a large mobilization aimed at CO2 mitigation. Herein, in the spirit of the transformation of a waste as CO2 into value added products, we propose an efficient preparation of two different hybrid systems based on aluminum chloride tetrastyrylporphyrin (TSP-Al-Cl) and 1,4-butanediyl-3,3′-bis-1-vinylimidazolium dibromide copolymerized in the presence (MWCNT-TSP-AlCl-imi) and in absence (TSP-AlCl-imi) of multi-walled carbon nanotubes (MWCNTs) for the CO2 utilization in the synthesis of cyclic carbonates. The so-prepared materials have been thoroughly characte…
POSS-Al-porphyrin-imidazolium cross-linked network as catalytic bifunctional platform for the conversion of CO2 with epoxides
2023
Two heterogeneous catalysts were prepared with the aim of following the promising path of CO2 fixation into epoxides. The synthetic procedure involves a radical copolymerization of an octavinylsilsesquioxane as inorganic core building block and tetrastyrylporphyrin aluminum chloride monomer (TSP-AlCl) in presence (POSS-TSP-AlCl-imiBr) or in absence (POSS-TSP-AlCl) of a bis-vinylimidazolium bromide salt (bis-imiBr), in order to investigate if the bifunctional heterogeneous material can display better catalytic performance than the separate species. All the solids were fully characterized and tested in the synthesis of cyclic carbonates starting from CO2 and several epoxides. The synergic coo…
Imidazolium-Functionalized Carbon Nanohorns for the Conversion of Carbon Dioxide
2016
Six new hybrid materials composed of carbon nanohorns (CNHs) and highly cross-linked imidazolium salts were easily synthesized using a one-step procedure based on the radical oligomerization of bis-vinylimidazolium salts (bVImiX) in the presence of pristine CNHs. The hybrid materials were characterized and employed as the sole catalysts for the conversion of carbon dioxide into cyclic carbonate by reaction with epoxides. The solids displayed excellent turnover number and productivity. Moreover, four catalysts were investigated in recycling experiments. Two catalysts containing an octyl linker between the imidazolium units and a bromide or an iodide anion showed no loss in activity after thr…
Undecylenic acid: A tunable bio-based synthon for materials applications
2016
International audience; An undecylenic acid-based monoglyceride prepared from glycidol and undecylenic acid is used as suitable and tunable synthon for polymerization applications. Epoxidation and acrylation reactions lead to photopolymerizable monomers while transesterification with dimethyl carbonate, metathesis and aminolysis reactions provide access to polyhydroxyurethane-based materials. The successive intermediates were synthesized according to a green chemistry approach implicating solvent-less and catalyzed reactions, and were at each step fully characterized by infrared, 1H and 13C{1H} NMR spectroscopy, elemental analysis and mass spectrometry. Analyses of the resulting polymer mat…
POSS-based 3D functional networks as catalysts for the conversion of carbon dioxide
2023
Oggi lo sviluppo di processi sostenibili è al centro dell'attenzione a causa delle emergenze climatiche. La Chimica Verde, con i suoi dodici principi sviluppati da Paul Anastas, si concentra sullo sviluppo di processi alternativi e più rispettosi dell'ambiente. Questa branca della chimica mostra come concetti quali la prevenzione dei rifiuti, l'uso di materie prime rinnovabili e la catalisi siano di grande importanza per rendere un processo più sostenibile. In questo contesto, l'anidride carbonica (CO2) rappresenta una delle materie prime più abbondanti, non tossiche e rinnovabili. La possibilità di riutilizzare la CO2 e di trasformare questa molecola in prodotti a valore aggiunto come i ca…
Reconsidering TOF calculation in the transformation of epoxides and CO2 into cyclic carbonates
2020
Abstract The combination of Lewis acids and Lewis bases, currently defined as catalysts and co-catalysts (or promoter) respectively, in the reaction between epoxides and CO2 to give cyclic carbonates, is discussed, starting from examples in which the Lewis base was used in larger amount with respect to the Lewis acid. In these cases, turnover frequency (TOF) values have been usually calculated taking into account solely the amount of the Lewis acid employed. The occurrence of two distinct reaction pathways, one catalysed by the sole Lewis base and the other one catalysed by the Lewis acid/Lewis base couple, in which the Lewis acid alone does not play a catalytic role, should bring researche…
A polyhedral oligomeric silsesquioxane-based catalyst for the efficient synthesis of cyclic carbonates
2015
Polyhedral oligomeric silsesquioxane functionalized with imidazolium chloride peripheries (POSS-Imi) was successfully synthesized through a novel synthesis protocol. The solid was extensively characterized via1H NMR, 13C NMR and IR spectroscopy as well as combustion chemical analysis, mass spectrometry and transmission electron microscopy. Moreover, an in-depth investigation through 29Si NMR was performed. POSS-Imi was used for the first time as a catalyst for the conversion of CO2 and epoxides into cyclic carbonates with excellent results in terms of both yield and selectivity. The catalyst displayed improved catalytic performance with respect to unsupported 1-butyl-3-methylimidazolium chl…
Polyhedral Oligomeric Silsesquioxane Based Catalyst for the Efficient Synthesis of Cyclic Carbonates
2015
In this work, the synthesis of a novel imidazolium-based polyhedral oligomeric silsesquioxane (POSS-mim-Cl) material is presented. The new nanometer-size organosilica based compound was employed for chemical fixation of CO2 into epoxide under homogeneous conditions. The target reaction was represented by the obtention of cyclic carbonates starting from epoxides and CO2. Particularly, styrene oxide was chosen as reference substrate. In addition, different parameters (solvent, temperature, pressure of CO2, and mass of the catalyst) were modified to find the best condition for CO2 conversion. The catalyst POSS-mim-Cl displayed good catalytic performances, the best results being obtained at 40 …
Hybrid catalysts for CO 2 conversion into cyclic carbonates
2019
The conversion of carbon dioxide into valuable chemicals such as cyclic carbonates is an appealing topic for the scientific community due to the possibility of valorizing waste into an inexpensive, available, nontoxic, and renewable carbon feedstock. In this regard, last-generation heterogeneous catalysts are of great interest owing to their high catalytic activity, robustness, and easy recovery and recycling. In the present review, recent advances on CO 2 cycloaddition to epoxide mediated by hybrid catalysts through organometallic or organo-catalytic species supported onto silica-, nanocarbon-, and metal-organic framework (MOF)-based heterogeneous materials, are highlighted and discussed.