Pd black

Although the yields are not high, PdCU or Pd black catalyzes oxo reactions of alkenes with CO and H2 to give aldehydes[32]. 

H2/Pd-C. If hydrogenation is carried out in the presence of (BOC)20, the released amine is directly converted to the BOC derivative. H2/Pd-C, NH3, —33°, 3-8 h, quant.When ammonia is used as the solvent, cysteine or methionine units in a peptide do not poison the catalyst. Pd-C or Pd black, hydrogen donor, solvent, 25° or reflux in EtOH, 15 min-2 h, 80-100% yield. Several hydrogen donors, including cyclohex-... 

Pd-Poly(ethylenimine), HC02H. This catalyst system was reported to be better than Pd/C or Pd black for Z removal. 

H2, Pd black, EtOH, 45°, 92% yield.If the hydrogenolysis is performed in the presence of (B0C)20 or Fmoc-OSu, the released amine is converted to the BOC and Fmoc derivatives in situ ... 

Cyclohexadiene, Pd-black, 25°, 100% yield, imidazole = His(Bn). With H2/Pd-C, the normal conditions for benzyl group removal, it is difficult to remove the benzyl group on histidine without also causing the reduction of other aromatic groups that may be present. ... 

The ligandless Beletskaya catalysts, PdCl2(CH3CN)2 used in DMF or acetone with tin-substituted alkynes and sp -hybridized iodides and bromides. This system is very reactive and relatively cheap. The disadvantage is that it decomposes quickly under development of catalyticaUy inactive Pd-black particles [20 c]. 

AgPd Hydrogenation Methyl acrylate - Higher than Pd black - [189]... 

This new impurity proved to be derived from the Pd-catalyzed oxidation of DIPA to the enamine via P-hydride elimination. In fact, mixing Pd(OAc)2 with DIPA in DMF-d7 readily formed Pd black along with two species, primary amine and acetone, presumably derived from the enamine through hydrolysis. The resulting enamine or acetone then underwent a coupling reaction with iodoaniline 28. Heterocyclization through the arylpalladium(II) species provided 2-methyl indole 71, as shown in Scheme 4.19. 

Isomerization versus Reduction Reaction Pathways in the Hydrogenation of 3-Buten-2-ol and l,4-Pentadien-3-ol on Pd-Black... 

The general experimental procedure employed in the study here has been described previously (7), thus only a brief overview is presented here. For all experiments, 45 mL deionized water and catalyst (50 mg Pd-black for 3-buten-2-ol and 25 mg for l,4-pentadien-3-ol) were added to the reaction cell. For ultrasound-assisted, as well as stirred (blank) experiments, the catalyst was reduced with hydrogen (6.8 atm) in water for 5 minutes at an average power of 360 W (electrical 90% amplitude). The reagents (320 mg 3-buten-2-ol or 360 mg l,4-pentadien-3-ol) were added to the reduced catalyst solution to achieve... 

In the enantioselective hydrogenation of isophorone in the presence of (-)-DHVIN modifier the best optical purity was afforded by small dispersion (<0,05) Pd black catalyst (up to 55%) (7). The influence of the preparation method of Pd black on the optical yield was reported (8). A correlation was found between the oxidation state of the metal surface and the enantioselectivity, the catalyst having more oxidised species on its surface giving higher enantiomeric excess, while the Pd black with lower surface area was more enantioselective. 

The object of the present study was to use in the above mentioned hydrogenations improved carbon supported catalysts, which could compete with the Pd black catalyst. Carbon materials are common supports, their surface properties can be modified easily and it is possible to prepare carbons with different proportion of micro-, meso- and macropores, which can be key factors influencing their performances. A highly mesoporous carbon was synthesised and used as support of Pd catalysts in the enantioselective hydrogenations. To our knowledge this is the first report on the use of highly mesoporous carbon for the preparation of Pd catalysts for liquid-phase hydrogenation. 

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