611-14-3Relevant articles and documents
Brown,Smoot
, p. 6255,6256 (1956)
Structural evolution of bimetallic Pd-Ru catalysts in oxidative and reductive applications
Shen, Jing,Scott, Robert W.J.,Hayes, Robert E.,Semagina, Natalia
, p. 350 - 360 (2015)
Abstract Two types of bimetallic Pd-Ru catalysts with a 2:1 Ru:Pd molar ratio were prepared using a poly-(vinylpyrrolidone) stabilizer: one alloy structure with mixed-surface atoms and one core-shell structure with a Pd core and Ru shell, which were confirmed by a surface-probe reaction at mild conditions. In indan hydrogenolysis at 350 °C, inversion of the core-shell structure began with Pd atoms appearing on the surface of the particles. Both catalysts displayed distinctively different catalytic behavior and indicated the importance of structure control for this particular application within a studied time frame. For methane combustion over the 200-550 °C temperature range, both structures demonstrated identical activity, which was due to their structural evolution to one nanoparticle type with Pd-enriched shells, as evidenced by extended X-ray absorption fine structure.
Matsuura et al.
, p. 127,128-134 (1972)
Probing the Source of Enhanced Activity in Multiborylated Silsesquioxane Catalysts for C-O Bond Reduction
Gagné, Michel R.,Starr, Hannah E.
supporting information, (2022/02/05)
A family of variably borylated silsesquioxanes can be conveniently synthesized by the hydroboration of vinyl- and allyl-modified silsesquioxanes using Piers' borane (HB(C6F5)2). The catalytic activity of these Lewis acidic catalysts has been examined for the reduction of isochroman with 1,1,3,3-tetramethyldisiloxane, and loadings as low as 0.05 mol % boron are feasible. Despite scaling all catalytic reactions to the boron Lewis acid, the multiborylated silsesquioxanes showed exceptional catalytic activity compared to the monoborylated silsesquioxanes. Even at a catalyst loading of 0.05 mol %, the multiborylated catalyst could achieve a TOF of 7 min-1. The ideal position for boron on the silsesquioxanes was at the C2 position, as this position did not inhibit Lewis acidity via the β-silicon effect (at C1) or limit the inductive electron-withdrawing ability of the silsesquioxane core (at C3). The high catalyst activity is attributed to the increased Lewis acidity of the multiborylated silsesquioxanes.
Effect of solvent in the hydrogenation of acetophenone catalyzed by Pd/S-DVB
Bereta, Tomasz,Mieczyńska, Ewa,Ronka, Sylwia,Tylus, W?odzimierz,Trzeciak, Anna M.
, p. 5023 - 5028 (2021/03/26)
A solvent effect was found in the hydrogenation of acetophenone catalyzed by a new Pd/S-DVB catalyst, immobilized on a styrene (S)/divinylbenzene (DVB) copolymer containing phosphinic groups. The porous structure of the catalyst was characterized by a specific surface area of 94.7 m2g?1. The presence of Pd(ii) and Pd(0) in Pd/S-DVB was evidenced by XPS and TEM. Pd/S-DVB catalyzes the hydrogenation of acetophenone (APh) to 1-phenylethanol (PhE) and ethylbenzene (EtB). The highest conversion of APh was obtained in methanol (MeOH) and in 2-propanol (2-PrOH), while in water it was lower. The conversion of APh correlates well with the hydrogen-bond-acceptance (HBA) capacity of the solvent. However, in all binary mixtures of alcohol and water the APh conversion and the yield of products significantly decreased. The observed inhibiting effect can be explained by the microheterogeneity of these mixtures and the blocking of the catalyst surface restricting access of the substrates to the Pd centers.
Metal-Organic Framework-Confined Single-Site Base-Metal Catalyst for Chemoselective Hydrodeoxygenation of Carbonyls and Alcohols
Antil, Neha,Kumar, Ajay,Akhtar, Naved,Newar, Rajashree,Begum, Wahida,Manna, Kuntal
supporting information, p. 9029 - 9039 (2021/06/28)
Chemoselective deoxygenation of carbonyls and alcohols using hydrogen by heterogeneous base-metal catalysts is crucial for the sustainable production of fine chemicals and biofuels. We report an aluminum metal-organic framework (DUT-5) node support cobalt(II) hydride, which is a highly chemoselective and recyclable heterogeneous catalyst for deoxygenation of a range of aromatic and aliphatic ketones, aldehydes, and primary and secondary alcohols, including biomass-derived substrates under 1 bar H2. The single-site cobalt catalyst (DUT-5-CoH) was easily prepared by postsynthetic metalation of the secondary building units (SBUs) of DUT-5 with CoCl2 followed by the reaction of NaEt3BH. X-ray photoelectron spectroscopy and X-ray absorption near-edge spectroscopy (XANES) indicated the presence of CoII and AlIII centers in DUT-5-CoH and DUT-5-Co after catalysis. The coordination environment of the cobalt center of DUT-5-Co before and after catalysis was established by extended X-ray fine structure spectroscopy (EXAFS) and density functional theory. The kinetic and computational data suggest reversible carbonyl coordination to cobalt preceding the turnover-limiting step, which involves 1,2-insertion of the coordinated carbonyl into the cobalt-hydride bond. The unique coordination environment of the cobalt ion ligated by oxo-nodes within the porous framework and the rate independency on the pressure of H2 allow the deoxygenation reactions chemoselectively under ambient hydrogen pressure.
