Palladium oxidations

Paliadiumoxydul, n. palladous oxide, palladium-(II) oxide, -nitrat, n. palladous nitrate, palladium (II) nitrate, -salz, n. palladous salt, palladium (ID salt. 

Eigure 3.9 shows temperatures for 50% conversion (T o) of CH3OH and its decomposed derivatives over Pt/y-Al203, Pd/y-Al203, and Au/a-Pe203 catalysts [52]. Eor MeOH oxidation, palladium is more active than platinum, while gold lies in between. These three catalysts are similarly active for the oxidation of HCHO and HCOOH. Catalytic oxidation at temperatures below 0°C can proceed over palladium and platinum for H2 oxidation, while it happens over gold for CO oxidation. 

LaCo03. In such a situation, tentative explanations on possible changes in the chemical environment of oxidic palladium species could be proposed with a subsequent stabilisation of oxidic Pd species in the perovskite matrix. The formation of well-dispersed Pd"1 entities could further inhibit the formation of sulphate generally observed on PdO at high temperature [113,115],... 

Intramolecular oxidative palladium couplings of alkenylamino indoles allow the preparation of azepinoindole derivatives in high yields (2005MI707). 

Synonyms palladium (11) oxide palladium monoxide palladous oxide... 

Here, the sites where CO is hydrogenated are not necessarily an oxidized palladium atom. Pd could be the site where methoxy is formed whereas methane is produced on Pd°. 

The use of a stoichiometric amount of palladium acetate, a fact that biases the original oxidative ring closure reactions, can be overcome by the use of an oxidant in the process, which re-oxidizes palladium(O) that is formed in the final step of the ring closure. Such a transformation is presented in 3.78., where an anilino-benzoquinone was ringd closed to give an indoloquinone in the presence of a catalytic amount of palladium acetate and a stoichiometric amount of copper(II) acetate.98... 

The important carrier effect is only possible with highly dispersed palladium—i.e., easily oxidized palladium. IR results corroborate this assumption. Upon reduction by hydrogen at 200° C, treatment with oxygen at 300°C produces Pd(II) ions. Reversibility is only partial, and the disappearance of the metal can be explained by the oxidation of part of the metallic palladium into bulk palladium oxide. 

Materials. Palladium acetate was prepared by oxidizing palladium black in acetic acid by 02 or by nitric acid (20). Material from nitric acid oxidation was crystallized five times or more before use, or more often, was purified by the following procedure. Finely powdered palladium acetate was made into a paste with sulfuric acid and digested at 140°-150°C for 30 min. Palladium (II) was thus converted into palladium sulfate, and crucial impurities were destroyed. Palladium sulfate was dissolved in water. After the sulfuric acid was neutralized, the addition of excess acetic acid precipitated purified palladium acetate. Oxi-dizable impurities were removed from acetic acid by repeated fractionation from CrOa and KMn04 solutions. Olefins were treated with alumina before use to remove peroxides. The reproducibility of the rate data was used as a test of the purity of reagents since the results were erratic when inadequate precautions had been taken. 

N-Potassium phthalimide Hydrazine hydrate Chloroacetonitrile Platinum oxide Palladium on charcoal... 

Itoh, N. Govind, R. Development of a Novel Oxidative Palladium Membrane Reactor AIChE Symposium Series 268, Govind and Itoh, eds. New York, NY 1989. 

This review deals only with the heterogeneous oxidation of-carbon monoxide by solid materials which show some catalytic activity or a fast surface reaction. It does not include purely stoichiometric reagents used in detection and analysis, such as iodine pentoxide, mercuric oxide, palladium salts activated by molybdenum salts, or liquid-gas systems. A review of such agents has recently been presented elsewhere (11). Furthermore, no attempt has been made to provide complete coverage of the numerous patents in this field, although a number of the more important ones are mentioned. 

Medical sources are fabricated with remotely operated, specially designed machines (8). The fabrication process involves production of Pt - 10% Ir-clad wire with a californium oxide-palladium cermet core. The wire is swaged and drawn to size, cut to length, and welded in a Pt - 10% Ir capsule. Nominally, medical sources contain from 0.3 yg 252cf in an individual seed (Figure 8) to 30 yg 252cf in an applicator tube (Figure 7). 

The billet contains a californium oxide-palladium core gold-brazed in a Pt - 10% Ir container (0.76-cm diameter x 3.56 cm long). The core is prepared by deposition of palladium on a fine precipitate of californium oxalate in an aqueous system (6). 

As shown in Equation (37), 4,5-dibromo-2-furaldehyde and methyl 4,5-dibromo-2-furoate underwent regioselective cross-coupling reaction at the 5-position with alkynes under Sonogashira-type conditions, presumably due to the activation of the 5-position by the electron-withdrawing groups at the 2-position toward oxidative palladium insertion <1998TL1729, 1999EJO2045>. 

In the oxidation of 2-octenyl acetate, in addition to the normal oxidation, palladium-catalyzed allylic rearrangement and subsequent oxidation took place to give a small amount of 3-acetoxy-2-octanone as a byproduct. Ethers of secondary allylic alcohols also underwent the regioselective oxidation to give the corresponding 3-alkoxy ketones in 30-40% yields. But in this case too, by-products derived from the allylic reanangement a subsequent oxidation were also detected. Results of the oxidation of some allyl ethers are shown in Table 3. °... 

Post-reaction XPS detected considerable amounts of CH (about 0.7 ML), indicating that CHx may again have been involved in the reaction, and also a Pd3d BE shift (approximately 0.6 eV), which points to a partial oxidation of the palladium nanoparticles during the reaction (297,504) (Fig. 55c). It is inferred that the oxidation was not complete, because the frequencies of adsorbed CO were still characteristic of CO on metallic palladium (Fig. 55b), and full oxidation to PdO particles would result in BE shifts of about + 1.5eV (514). The observed BE shift (characteristic of oxidized palladium) could be (partly) reversed by reaction... 

Vigorous exothermic reaction with benzene + Raney nickel catalyst metals (e.g., lithium calcium barium strontium sodium potassium above 300°C) palladium(II) oxide palladium trifluoride l,l,l-tris(hydroxymethyl)nitromethane + nickel catalyst. 

The preparation of paUadous oxide-palladium black and its use as a catalyst in the reduction of organic compounds have been studied by Shriner and Adams. Palladium black and coUoidal palladium have been widely used as hydrogenation catalysts. ... 

Tetrahydrofuran has been prepared by the reduction of furan in the vapor phase with a nickel catalyst at 170°, in butyl alcohol at 50° with Raney nickel catalyst/ and with palladous oxide-palladium black in the absence of a solvent. ... 

PdCl2/CuCl2/02 (Wacker oxidation) (palladium chloride/cupric chloride/oxygen) Sulpholane/water RT to 100 terminal alkenes-> methyl ketones... 

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