122-97-4Relevant articles and documents
Molybdenum oxide-mediated facile aliphatic nucleophilic fluorination
Said, Madhukar S.,Khandare, Lina,Shinde, Sandip S.
, p. 59 - 62 (2017)
A facile aliphatic nucleophilic fluorination with cesium fluoride in the presence of molybdenum oxide as a catalyst has been demonstrated. Reactivity of molybdenum oxide in nanocrystal form was found to be chemoselective in the presence of water. Furthermore, the reaction is highly specific with alkyl sulfonate substrates.
Alumina-grafted SBA-15 as a high performance support for Pd-catalysed cinnamyl alcohol selective oxidation
Parlett, Christopher M.A.,Durndell, Lee J.,Machado, Andreia,Cibin, Giannantonio,Bruce, Duncan W.,Hondow, Nicole S.,Wilson, Karen,Lee, Adam F.
, p. 46 - 55 (2014)
Ultrathin alumina monolayers grafted onto an ordered mesoporous SBA-15 silica framework afford a composite catalyst support with unique structural properties and surface chemistry. Palladium nanoparticles deposited onto Al-SBA-15 via wet impregnation exhibit the high dispersion and surface oxidation characteristic of pure aluminas, in conjunction with the high active site densities characteristic of thermally stable, high-area mesoporous silicas. This combination confers significant rate enhancements in the aerobic selective oxidation (selox) of cinnamyl alcohol over Pd/Al-SBA-15 compared to mesoporous alumina or silica supports. Operando, liquid-phase XAS highlights the interplay between dissolved oxygen and the oxidation state of palladium nanoparticles dispersed over Al-SBA-15 towards on-stream reduction: ambient pressures of flowing oxygen are sufficient to hinder palladium oxide reduction to metal, enabling a high selox activity to be maintained, whereas rapid PdO reduction and concomitant catalyst deactivation occurs under static oxygen. Selectivity to the desired cinnamaldehyde product mirrors these trends in activity, with flowing oxygen minimising CO cleavage of the cinnamyl alcohol reactant to trans-β-methylstyrene, and of cinnamaldehyde decarbonylation to styrene.
Aliphatic carbonyl reduction promoted by palladium catalysts under mild conditions
Musolino, Maria Grazia,Busacca, Concetta,Mauriello, Francesco,Pietropaolo, Rosario
, p. 77 - 86 (2010)
The catalytic reduction of aliphatic aldehydes (propanal, pentanal and hexanal) and ketones (pentan-2-one, pentan-3-one and cyclohexanone) to the corresponding alcohols promoted by palladium catalysts, such as Pd/CoO, Pd/NiO, Pd/ZnO, Pd/Fe2O3 and Pd/CeO2, was performed under mild conditions (0.1 MPa H2 and 323 K) for the first time. All the catalysts were obtained by the co-precipitation technique and characterized by BET, TPR, XRD, TEM and XPS. The co-precipitation method allows, after reduction, formation of bimetallic ensembles (Pd/CoO and Pd/ZnO in less extent) or alloys (Pd/NiO) thus changing the electronic properties of the palladium on the surface, increasing the d-orbital energy at the Fermi level and permitting the activation of the C{double bond, long}O bond also in aliphatic carbonyls. Accordingly the reactivity of Pd/Fe2O3 and Pd/CeO2 towards aliphatic aldehydes is attributed to a redox interaction of Fe3+ or Ce4+ with the oxygen moiety of the carbonyl bond, leading to the π* orbital energy decrease. Analogous reactions, carried out with Pd/CoO and Pd/Fe2O3, prepared by impregnation, gave a very slow reduction. Additional catalytic tests were performed with aromatic carbonylic compounds in order to compare their reactivity with that of aliphatic systems: the differences were interpreted taking into account the Δ energy value between π and π* orbitals, much lower in aromatic carbonyls, that favours an easier activation of the aromatic C{double bond, long}O bond.
Enhanced Pd-catalyzed hydrogenation of olefins within polymeric microreactors under organic/aqueous biphasic conditions
Lan, Yang,Zhang, Minchao,Zhang, Wangqing,Yang, Li
, p. 3670 - 3673 (2009)
A microreactor of a water-soluble hollow polymeric microsphere with Pd nanoparticles immobilized in the wall was proposed for the hydrogenation of olefins under organic and aqueous biphasic conditions. It was found that the microreactor was stable and was used in practical application for continuous hydrogenation of olefins on a technical scale without deactivation in activity. It was composed of three parts, such as the outer corona of polyacrylamide (PAM), the cross-linked and hydrophobic wall of poly[styrene-co-2-(acetoacetoxy) -ethylmethacrylate] (PS-co-PAEMA), and 3.9 mm Pd nanoparticles. Hollow microspheres were constructed using several procedures of seed polymerization along with removal of the seed for the synthesis of the microreactor. It was observed that the microreactor dispersed easily in aqueous phase due to the presence of the hydrophilic PAM corona. The hydrogenation of CA with H 2 was also evaluated to investigate hydrogenation of olefins within the microreactor.
Characterization and catalytic activity of palladium dispersed on Kratschmer-Huffman (K-H) soot
Datta, Arunabha,Khwaja, Hanif I.,Kelkar, Ravindra Y.,Saple, Ashok R.,Datta, Monika
, p. 851 - 852 (1996)
Palladium dispersed on K-H soot, both before and after extraction with solvents, is shown to exist in a range of oxidation states and is an active catalyst for the disproportionation of cinnamyl alcohol to cinnamaldehyde and dihydrocinnamyl alcohol under conditions where a commercial Pd/C catalyst is inactive.
Regiospecific reduction of oxetanes with lithium under aprotic conditions
Rama,Pasha
, p. 1073 - 1074 (2000)
Substituted oxetanes have been found to give exclusively terminal alcohols by regiospecific ring-opening with lithium and biphenyl (cat.) in THF at reflux. (C) 2000 Elsevier Science Ltd.
N-Heterocyclic Olefin Catalyzed Silylation and Hydrosilylation Reactions of Hydroxyl and Carbonyl Compounds
Kaya, U?ur,Tran, Uyen P.N.,Enders, Dieter,Ho, Junming,Nguyen, Thanh V.
, p. 1398 - 1401 (2017)
N-Heterocyclic olefins (NHOs), the alkylidene derivatives of N-heterocyclic carbenes (NHCs), have recently emerged as a new family of promising organocatalysts with strong nucleophilicity and Br?nsted basicity. The development of a novel method is shown using NHOs as efficient promoters for the direct dehydrogenative silylation of alcohols or hydrosilylation of carbonyl compounds. Preliminary results of the first NHO-promoted asymmetric synthesis are also discussed.
Amphiphilic ionic liquid stabilizing palladium nanoparticles for highly efficient catalytic hydrogenation
Zhu, Wenwen,Yang, Hanming,Yu, Yinyin,Hua, Li,Li, Huan,Feng, Bo,Hou, Zhenshan
, p. 13492 - 13500 (2011)
The highly water-soluble palladium nanoparticles (NPs) were synthesized by using the amphiphilic poly(ethylene glycol)-functionalized dicationic imidazolium-based ionic liquid (C12Im-PEG IL) as a stabilizing agent. The aqueous dispersed palladium NPs in the range of 1.9 ± 0.3 nm were observed by transmission electron microscopy (TEM). The physicochemical properties of C12Im-PEG IL in aqueous phase have been characterized by electrical conductivity, surface tension and dynamic light scattering (DLS) measurements. It was demonstrated that the amphiphilic ionic liquid can form micelles above its critical micelle concentration (CMC) in aqueous solution and the micelles played a crucial role in stabilizing the palladium NPs and thus promoted catalytic hydrogenation. Furthermore, the dicationic ionic liquid can also act as a gemini surfactant and generated emulsion between hydrophobic substrates and the catalytic aqueous phase during the reaction. The aqueous dispersed palladium NPs showed efficient activity for the catalytic hydrogenation of various substrates under very mild conditions and the stabilizing Pd(0) nanoparticles (NPs) can be reused at least eight times with complete conservation of activity. the Owner Societies 2011.
Chemoselective reduction of aldehydes using decaborane in aqueous solution
Lee, Seung Hwan,Nam, Mi Hye,Cho, Min Young,Yoo, Byung Woo,Rhee, Hak June,Yoon, Cheol Min
, p. 2469 - 2474 (2006)
Reduction of aldehydes using decaborane (B10H14) in an aqueous solution gave the corresponding alcohol chemoselectively in good to high yields. Copyright Taylor & Francis Group, LLC.
Scrap waste automotive converters as efficient catalysts for the continuous-flow hydrogenations of biomass derived chemicals
Cova, Camilla Maria,Zuliani, Alessio,Manno, Roberta,Sebastian, Victor,Luque, Rafael
, p. 1414 - 1423 (2020)
The catalytic activity of scrap ceramic-cores of automotive catalytic converters (SCATs) was investigated in the continuous-flow hydrogenation of different biomass-derived chemicals. The waste SCAT powders were deeply characterized by ICP-MS, TGA, MP-AES, XRD, N2 physisorption, TPR, HRTEM and EDS before and after utilization as a catalyst. The hydrogenation reactions of isopulegol to menthol, cinnamyl alcohol to hydrocinnamyl alcohol, isoeugenol to dihydroeugenol, vanillin to vanillyl alcohol and benzaldehyde to benzyl alcohol were performed studying the influence of various reaction parameters (temperature, pressure, flow rate and concentration of the starting material) on the final yields. The outstanding performance and stability obtained for the low metal content of waste-derived catalysts can be attributed to the co-presence of different noble metals as well as to the composite structure itself.
