Rhodium oxides

EG may also be pioduced via glycolic acid using catalysts containing strong acids (66), cobalt carbonyl (67—69), rhodium oxide (68), or HE solvent (70,71) (see Glycols, ETHYLENE glycol). 

Rhodium compounds, 19 644-648 synthesis of, 19 646 uses for, 19 646-648 Rhodium oxide, 10 42 Rhodium plating, 9 822 19 648 Rhodium-platinum alloys, 19 602 Rhodochrosite, 15 540 Rhodochrosite ore, 15 589 Rhodococcus, as a host system for gene expression, 12 478 Rhodonite, 15 540 color, 7 331 Rhodopsin, 9 512 Rhoeadine, 2 90 Rhoedales... 

A very active elemental rhodium is obtained by reduction of rhodium chloride with sodium borohydride [27]. Supported rhodium catalysts, usually 5% on carbon or alumina, are especially suited for hydrogenation of aromatic systems [iTj. A mixture of rhodium oxide and platinum oxide was also used for this purpose and proved better than platinum oxide alone [i5, 39]. Unsaturated halides containing vinylic halogens are reduced at the double bond without hydrogenolysis of the halogen [40]. 

Laplante, F., Bernard, N., Tavares, A., Trasatti, S. and Guay, D. (2006) X-ray photoelectron spectroscopy and X-ray diffraction characterization of rhodium oxides in reductive conditions, in Electrocatalysis, Vol. 2005-11 (eds G.M. Brisard, R. Adzic, V. Birss and A. Wieckowski), The Electrochemical Society, Pennington, NJ. 

Rhodium oxide,200 cobalt carbonyl,201 rhodium and ruthenium carbonyls,202 and rhodium compounds203,204 were later found to be effective catalysts. A three-step mechanism with hydroformylation of the alkene to yield an aldehyde in the first step can be written [Eq. (7.24)]. Condensation to form an imine [Eq. (7.25)] (or enamine) and hydrogenation of this intermediate leads to the product amine ... 

The following commercial powder catalysts (all from Degussa) were used in the screening runs rhodium-platinum oxide (45,65% Rh, 19,8% Pt), rhodium oxide (58,2% Rh), platinum oxide (80,6% Pt), palladium-on-carbon (5% Pd) and platinum-on-carbon (5% Pt). 

Rylander and Kilroy studied the formation of cyclohexyl phenyl ether intermediate in the hydrogenation of phenyl ether over binary platinum-rhodium oxide catalysts in cyclohexane at room temperature and atmospheric hydrogen pressure. The yield of the intermediate varied greatly with the catalyst composition. The highest yield (48%) was obtained over the catalyst consisting of 30% Pt-70% Rh.149... 

The ethyl ester of / -hydroxybenzoic acid was hydrogenated to give high yields of the saturated 4-hydroxy ester either over Pd-SrC03 in dioxane (see eq. 11.24)113 or ethyl acetate195 at 155-160°C, and over rhodium oxide at 50-65°C or over ruthenium oxide at 95-100°C in ethanol with small amounts of acetic acid (see eq. 11.25),114 under high hydrogen pressures. 

The same hydrogenation was often inhibited at a later stage of the reaction with the rhodium oxide prepared by conventional sodium nitrate fusion. Rh-Al203 was used... 

Relatively little information is available on the electrocatalytic activity of thermally prepared rhodium oxide for oxygen evolution, this oxide having been investigated for the most part in conjunction with other oxide catalysts [242, 243], A Tafel slope of ca. 50 mV decade-1 has been observed at low... 

Rhodium oxide-Platinnm oxide (Nishimura catalyst). 

Corey et al have also synthesized 3 from 1. Their route involves reduction of 1 with a rhodium oxide-platinum oxide catalyst (this volume) to the corresponding amine, formylation, and dehydration to give 3. 

CATALYSTS Chlorotrisftriphenylphos-phine)rhodium(I). (S)-a-(R)-2-Di-phenylphosphinoferrocenyl ethyldl-methylamine. Hydridotrisftriisopropyl-phosphine)rhodium(I). Iridium black. 2,3-0-Isopropylidene-2,3-dihydroxy-l,4-bis(diphenylphosphino)butane. Lindlar catalyst. Nickel-Alumina. Palladium catalysts. Raney nickel. Rhodium oxide-Platinum oxide. 

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