Showing papers on "Palladium published in 1979"
TL;DR: In this article, the representative (E)-1-alkenyldisiamylboranes and 1-alkenyl-1,3,2-benzodioxaboroles readily obtainable via hydroboration of 1 -alkynes react with (1) halides or (1)-alkynyl halides in the presence of a catalytic amount of tetrakis(triphenylphosphine)palladium and base to give corresponding conjugated (E-dienes or (E-)enynes with high regio-and
1,731 citations
TL;DR: The reaction of aryl halides with alk-l-enylboranes, readily obtainable via monohydroboration of acetylenes, provides a conveninet new method for stereoselective synthesis of E-alkenes in high yields; these reactions are effectively catalysed by tetrakis(triphenylphosphine)palladium and bases such as sodium ethoxide as discussed by the authors.
Abstract: The reaction of aryl halides with alk-l-enylboranes, readily obtainable via monohydroboration of acetylenes, provides a conveninet new method for stereoselective synthesis of arylated (E)-alkenes in high yields; these reactions are effectively catalysed by tetrakis(triphenylphosphine)palladium and bases such as sodium ethoxide.
940 citations
818 citations
TL;DR: In this article, the reaction of substituted bromobenzenes with tetramethyltin catalyzed by 1 is accelerated by electron-withdrawing groups; however, a simple Hammett correlation is not observed.
Abstract: Palladium complexes catalyze the coupling of tetraorganotin compounds with benzyl and aryl halides, benzylchlorobis(triphenylphosphine)palladium(II) (1) being the catalyst of choice. Various functional groups are tolerated by this reaction and generally high yields of the cross-coupled products are obtained. Oxygen has a considerable accelerating effect on the reaction, whereas triphenylphosphine has little effect. The reaction of substituted bromobenzenes with tetramethyltin catalyzed by 1 is accelerated by electron-withdrawing groups; however, a simple Hammett correlation is not observed. Optically active ..cap alpha..-deuteriobenzyl bromide reacts with tetramethyltin to afford optically active ..cap alpha..-deuterioethylbenzene with inversion of configuration. Homocoupling is the main reaction observed when lithium or Grignard reagents react with benzyl chloride under the influence of various palladium catalysts.
353 citations
TL;DR: In this paper, the average diameters of metal particles in the colloidal dispersions of palladium, rhodium, platinum, iridium, and osmium in poly(vinyl a...
Abstract: Colloidal dispersions of rhodium, palladium, osmium, iridium, and platinum are prepared by refluxing the methanol-water solutions of rhodium(III) chloride, palladium(II) chloride, osmium(VIII) oxide, sodium chloroiridate, and chloroplatinic acid, respectively, in the presence of poly(vinyl alcohol) as a protective colloid. The preparations of colloidal dispersions of rhodium are successful in the presence of vinyl polymer with polar group such as poly(vinyl alcohol), polyvinylpyrrolidone, or poly(methyl vinyl ether). Polyethyleneimine, gelatin, polyethylene glycol), and dextran are ineffective as the protective colloid. Water-soluble primary alcohols such as methanol and ethanol, water-soluble secondary alcohols such as 2-propanol, and water-soluble diethers such as 1,4-dioxane are available as reductants for preparation of the colloidal dispersion of rhodium. The average diameters of metal particles in the colloidal dispersions of palladium, rhodium, platinum, iridium, and osmium in poly(vinyl a...
278 citations
TL;DR: In this paper, a modified version of the Wacker oxidation was proposed, which involves reversible formation of 11 by external attack of water on 8, followed by a rate-determining dissociation of a chloride ligand from 11.
Abstract: Palladium(I1)-catalyzed oxidation of specifically deuterated ethenes in water in the presence of cupric chloride and chloride ion has been studied. Stereospecific formation of threo1,2-dideuterio-2-chloroethanol (threo-3) from ( E ) 1,2-dideuterioethene ( ( E ) 2 ) indicates that the hydroxypalladation step in the Wacker oxidation is a trans process. Generation of an erythro-P-hydroxyethylpalladium complex (6 ) from erythro-P-hydroxyethylmercuric chloride (5) in the presence of CuC12LiCl also results in the formation of rhreo-3. Analyses of the deuterated products were done by microwave spectroscopy. A new (modified) mechanism is proposed, which involves reversible formation of 11 by external attack of water on 8, followed by a rate-determining dissociation of a chloride ligand from 11.
247 citations
239 citations
171 citations
Patent•
11 Jan 1979
TL;DR: In this article, small amounts of a promoter comprising palladium and ruthenium enhance the combustion of carbon monoxide within the regeneration zone of a catalytic cracking unit without simultaneously causing the formation of excessive amounts of nitrogen oxides.
Abstract: Small amounts of a promoter comprising palladium and ruthenium enhance the combustion of carbon monoxide within the regeneration zone of a catalytic cracking unit without simultaneously causing the formation of excessive amounts of nitrogen oxides. The palladium-ruthenium promoter also enhances the capture of sulfur oxides by suitable absorbents within the regeneration zone of a catalytic cracking unit without causing the formation of excessive amounts of nitrogen oxides. The ratio by weight on an elemental metal basis of palladium to ruthenium is from about 0.1 to about 10.
161 citations
160 citations
TL;DR: The structural characteristics of 30 compounds with the composition RMe2X2 have been studied for rare earth (or uranium), Me = rhodium, palladium, silver, iridium, platinum or gold and X = silicon or germanium.
Abstract: The structural characteristics of about 30 compounds with the composition RMe2X2 have been studied for R = rare earth (or uranium), Me = rhodium, palladium, silver, iridium, platinum or gold and X = silicon or germanium Their structures proved to be related to the Al4Ba (ThCu2Si2) types The average atomic volumes of these phases are compared with those of similar groups of alloys and are briefly discussed Special reference is made to the cerium and ytterbium compounds and the behaviour of these elements is compared with that shown in their binary alloys
TL;DR: Arylation of BrZnCH2CO2CH2CH3 by aromatic halides proceeds smoothly and in fair yield in a mixture of dimethoxymethane and a dipolar aprotic solvent (HMPA, NMR (N-methylpyrrolidone), DMF, DMSO) when catalysed by soluble nickel or palladium complexes.
TL;DR: In this paper, the authors used the permeability time-lag method to determine the diffusivity of hydrogen in palladium in the temperature range 496-946°C.
TL;DR: Palladium(0)phosphine complexes catalyse the cyclodimerisation of methylenecyclopropanes and carbon dioxide with opening of the three-membered ring to give fivemembered lactones as mentioned in this paper.
Abstract: Palladium(0)–phosphine complexes catalyse the cyclodimerisation of methylenecyclopropanes and carbon dioxide with opening of the three-membered ring to give five-membered lactones.
TL;DR: Dichloro[1,1′-bis(diphenylphosphino)ferrocene]palladium(II) was found to be an effective catalyst for the cross-coupling reaction of sec -butylmagnesium chloride with bromobenzene, β-bromostyrene, and 2-βromopropene to give the corresponding sec-butyl derivatives in exceedingly high yields as discussed by the authors.
TL;DR: In this paper, the reaction of allylic acetates with tetrakis (triphenylphosphine) palladium leads to positional and stereochemical isomerism and a mechanism is proposed.
TL;DR: In this paper, the adsorption of carbon monoxide on a series of small particle palladium-gold alloys was investigated by infrared spectroscopy, and the results indicated that both ligand and ensemble effects are important when carbon dioxide is adsorbed on small, palladium gold particles.
TL;DR: In this paper, the chemisorption of CO and H 2 on two series of Pd/silica catalysts, reduced at 300 or 450 °C and containing 0.5 to 25.0% Pd, was measured.
TL;DR: In this paper, the authors determined the bulk permeability of three stainless steels (309S, a weldable A-286 and 21-6-9) using tritium and deuterium driving pressures up to 100 kPa.
TL;DR: In this paper, a new generally applicable route for the preparation of binuclear organometallic palladium(II) complexes is described, and the structure of the novel palladium complexes is discussed.
Eni1
TL;DR: In this paper, a scheme accounting for the ligand influence was presented, showing that the effect of the ligands, the CO pressure and added base on the carbonylation of methanol with carbon monoxide to dimethyl oxalate and dimethyl carbonate is mainly related to their electronic properties.