- Taking advantage of a terpyridine ligand for the deposition of Pd nanoparticles onto a magnetic material for selective hydrogenation reactions
-
A hybrid terpyridine ligand was designed to functionalize a magnetic support constituted of magnetite cores surrounded by a silica shell with the aim of improving the stabilization of supported-palladium nanoparticles for the later application of the obtained composite nanomaterial in hydrogenation catalysis. The preparation of the nanomaterial was performed by direct decomposition of the organometallic complex [Pd2(dba)3] on the terpyridine-modified magnetic support providing well-dispersed Pd NPs of 2.5 ± 0.6 nm mean size. This new nanomaterial is a highly active catalyst for the hydrogenation of cyclohexene under mild conditions reaching turnover frequencies up to ca. 58000 h-1 or 129000 h-1 when corrected for surface Pd atoms. Furthermore, in the hydrogenation of β-myrcene, this nanocatalyst is highly selective for the formation of monohydrogenated compounds. When compared to a similar nanocatalyst consisting of palladium nanoparticles supported on an amino-modified magnetic support or on Pd/C, the activity and selectivity of the nanocatalyst are largely increased. These results show how the design of an appropriate hybrid ligand used to functionalize the support can strongly influence the catalytic properties of supported metal nanoparticles. The Royal Society of Chemistry 2013.
- Guerrero, Miguel,Costa, Natalia J. S.,Vono, Lucas L. R.,Rossi, Liane M.,Gusevskaya, Elena V.,Philippot, Karine
-
p. 1441 - 1449
(2013/07/05)
-
- Study on selectivity of β-myrcene hydrogenation in high-pressure carbon dioxide catalysed by noble metal catalysts
-
Hydrogenation of monoterpenes, such as β-myrcene, in high-density carbon dioxide over 0.5 wt.% Pd, or Rh, or Ru supported on alumina was investigated. Hydrogenation catalysed by Rh and Ru is generally faster in a single supercritical (sc) phase (gaseous reagents and solid catalyst) than in a biphasic system (liquid + gas reactants + solid catalyst). The reaction catalysed by Pd occurs faster in two phases. The final composition of the reaction mixture is strongly dependent on the noble metal catalyst used for the reaction. Palladium gives mainly 2,6-dimethyloctane (≈95%), rhodium produces 2,6-dimethyloctane with a yield higher than 40%, and around 40% of 2,6-dimethyloct-2-ene, while ruthenium gives around 10% of 2,6-dimethyloctane and 50% of 2,6-dimethyloct-2-ene leaving the highest amount of unreacted β-myrcene. The Pd catalyst is highly active with an excellent selectivity in enabling the one-pot synthesis of 2,6-dimethyloctane through β-myrcene hydrogenation in the presence of scCO2. The overall activity of the noble metal catalysts decreased in the order Pd > Rh > Ru. The problem of leaching of the active metal from the catalyst rod was also investigated. The Royal Society of Chemistry 2009.
- Bogel-Lukasik,Gomes Da Silva,Nogueira,Bogel-Lukasik,Nunes Da Ponte
-
experimental part
p. 1847 - 1856
(2011/03/19)
-
- Electroreductive cyclisation of unsaturated halides catalysed by nickel macrocyclic complexes
-
The indirect electroreduction of unsaturated aliphatic halides using Ni(II) complexes as electron-transfer mediators is achieved in N,N'-dimethylformamide by constant current electrolysis between a cathode and a sacrificial anode in a diaphragmless cell. Cyclic compounds are obtained in low to high yields in conditions that avoid the usual preparation using organotin reagents.
- Dunì?ach,Esteves,Freitas,Medeiros,Olivero
-
p. 8693 - 8696
(2007/10/03)
-
- Photochemical Transformations VI: Organic Iodides (Part 5) - Templet Effect of Transition Metal Ions on Photocyclization of Some Olefinic Acyclic Terpene Iodides
-
Photocyclization of citronellyl iodide in the presence of certain transition metal salts especially CuCl, results in a significant increase (from 16percent to 35percent) in the yield of the cyclization products.Similar results have been obtained with geranyl and neryl iodides (11, 17).This enhancement of cyclization/elimination ratio is sought to be explained in terms of a templet effect of the transition metal ion.
- Subbarao, Kanury V.,Damodaran, N. P.,Dev, Sukh
-
p. 1008 - 1011
(2007/10/02)
-
- PHOTOCHEMICAL TRANSFORMATIONS-II ORGANIC IODIDES-II: CITRONELLYL IODIDE, 2,3-DIHYDRO-6(Z)-FARNESYL AND 2,3-DIHYDRO-6(E)-FARNESYL IODIDES
-
Experimental parameters governing ?-electrons participation during photolysis of citronellyl iodide have been investigated.Photoproducts resulting from irradiation of 2,3-dihydro-6(Z)- and 2,3-dihydo-6(E)-farnesyl iodides have been characterised.
- Saplay, K. M.,Sahni, Ranjana,Damodaran, N. P.,Dev, Sukh
-
p. 1455 - 1461
(2007/10/02)
-