1,721,058 research outputs found
Ru-based Oxidation Catalysis
No full textRanging from the oxidative conversion of water to O2 to the elegant hydroxylation of olefins and to oxidative
dehydrogenation of alcohols Ru-mediated oxidations are finding increasing application due to the unique properties of
this extremely versatile transition metal, whose oxidation state can vary from –II to +VIII. Covering recent
developments in both homogeneously and heterogeneously catalysed oxidations (in liquid-phase as well as in novel
reaction media), this tutorial review aims to provide investigators with a general picture of the chemical and structural
origins of the excellent performance of many ruthenium catalysts and to promote further advancements that, it is
envisaged, will soon benefit society at large
FluoRuGel: a versatile catalyst for aerobic alcohol oxidation in supercritical carbon dioxide
No full textA comparative analysis between metal-based aerobic catalysts shows that FluoRuGel, an hybrid fluorinated silica solgel
glass doped with the ruthenium species TPAP (tetra-n-propylammonium perruthenate), is a competitive catalyst for
the aerial oxidation of alcohols. In particular, the FluoRuGel/O2 system is well suited for carrying out convenient
oxidative dehydrogenations in dense phase CO2 smoothly affording high yields of a variety of structurally different
aldehydes and ketones of high purity. The potential rewards of this new technology are numerous and go beyond simple
elimination of both organic solvents and stoichiometric oxidants employed in traditional alcohol oxidations
Omeg@Silica: Entrapment and Stabilization of Sustainably Sourced Fish Oil
Full text linkFish oil rich in long-chain polyunsaturated fatty acids, vitamin D-3 and carotenoid pigments have been sustainably extracted from anchovy fillet leftovers using biobased limonene. The oil is conveniently stabilized by adsorption on periodic mesoporous silicas. The simplicity of the process, the high load of fish oil, and the biocompatible nature of mesoporous silica support numerous forthcoming applications of this new class of "Omeg@Silica" materials
Fluorinated Silica Gels Doped with TPAP as Effective Aerobic Oxidation Catalysts in Dense Phase Carbon Dioxide
No full textAbstract: Hybrid organic-inorganic fluorinated silica glasses doped with the ruthenium species TPAP (tetra-n-propylammonium perruthenate) are effective catalysts for the aerial oxidation of benzyl alcohol to benzaldehyde in dense phase CO2. Moderate silica fluorination (10%) by short-chain fluoroalkyl-containing monomers in the sol-gel polycondensation with TMOS affords highly active catalysts which at 75 oC and 220 bar selectively dehydrogenate the alcohol with oxygen as primary oxidant. Both the activity and the stability of the fluorinated materials vary with the degree of fluorination and the nature of the fluoroalkyl residue attached to the silica polymeric network. An explanation of the behaviour of doped sol-gel oxides in supercritical carbon dioxide is proposed which is thought to be of general validity for future practical applications to heterogeneously catalysed aerobic oxidations eliminating the current need for both organic solvents and stoichiometric oxidants
The Effects of Material Properties on the Activity of Sol-gel Entrapped Perruthenate under Supercritical Conditions
No full textSilica gels organically modified and doped with the ruthenium species tetra-n-propylammonium perruthenate (TPAP) are leach-proof, selective catalysts for the aerobic oxidation of alcohols to carbonyl compounds with dioxygen at low pressure in compressed carbon dioxide. The catalytic sol-gels are recyclable and the correlation between the reactivity of the materials and their surface polarity and textural properties suggests valuable information on the chemical behaviour of sol-gel entrapped silica catalysts in oxidation catalysis which is of relevant interest considering the importance of heterogeneous oxidative dehydrogenation of alcohols in fine chemistry. An explanation of the structure-activity relationship is proposed to provide guidelines for the further development of efficient solid oxidation catalysts for conversions in supercritical carbon dioxide
A Mechanistic Study on Alcohol Oxidations with Oxygen Catalysed by TPA-doped Ormosils in Supercritical Carbon Dioxide
No full textAbstract: The heterogeneous oxidation of various alcohols with oxygen catalysed by TPAP doped ormosils in scCO2 at 75 oC and 22.0 MPa has been studied in detail. Sol-gel segregation of TPAP into the inner porosity of organically modified silica along with the use of a reaction medium which does not dissolve the catalyst, prevents aggregation of oxidation-inactive ruthenium derivatives without the need of chemical tethering. Thus, at least 140 TONs may be obtained in the oxidation of primary alcohols with the formation of aldehydes as sole reaction product. Investigation of the oxidation mechanism shows that the catalytic process exhibits a first-order dependence on the amount of catalyst, a fractional order on the alcohol concentration and a negative order for oxygen pressures higher than 0.2 Pa. Evidence is reported for an associative oxidation mechanism simultaneously involving TPAP, organic substrate and oxygen
Sol-gel entrapped TPAP: An off-the-shelf catalyst set for the clean oxidation of alcohols
No full textSol-Gel Entrapped TPAP: An Off-the Shelf Catalyst Set for the Clean Oxidation of Alcohols
No full textWhether in supercritical CO2 or in organic solvent and using O2 or aqueous H2O2 as primary oxidants, the series
of sol-gel entrapped TPAP hybrid silica gels is a versatile class of oxidation catalysts suitable for the highly selective
conversion of alcohols to carbonyls. These materials are generally more stable and active than traditional polymersupported
analogues. This report summarizes recent findings showing the large potential of this technology for synthetic chemistr
A Circular Economy Approach to Fish Oil Extraction
No full textFish oil rich in polyunsaturated omega-3 fatty acids is extracted in high yield from anchovy filleting waste using d-limonene as green biosolvent in a simple solid-liquid extraction performed by mechanically stirring and maceration followed by limonene removal via evaporation under reduced pressure. As limonene is renewably obtained from waste orange peel, this method closes the materials cycle and establishes a circular economy process to obtain high quality fish oil from biowaste available worldwide in several million t/year amount. Significant economic, social and environmental benefits are anticipated
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