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Aqueous Palladium Chloride Reactions

B. Additions of Inorganic Palladium Compounds I. Aqueous Palladium Chloride Reactions... [Pg.7]

One of the first examples of this type of reaction and perhaps the one most investigated and best understood, is the oxidation of ethylene to acetaldehyde by aqueous palladium chloride. [Pg.7]

The aqueous palladium chloride oxidation of ethylene to acetaldehyde has been developed into an important commercial process. The discovery of how to make the reaction catalytic with respect to palladium chloride was, perhaps, as important to the process as the discovery of the oxidation reaction itself. This process known as the Wacker-Process, employs cupric chloride as a catalyst for the oxygen (air) reoxidation of... [Pg.9]

This elimination is reminiscent of the last step in the aqueous palladium chloride oxidation mentioned above and this reaction also may involve multiple hydride addition-elimination steps. Minor amounts of the normal products and Markovnikov products are also generally found in these reactions. Cupric chloride can be used as a reoxidant although the yields are generally lower than with an all acetate, non-catalytic reaction. [Pg.23]

Olefin oxidation with an aqueous palladium chloride solution according to eqs. (2)-(4) occurs stoichiometrically. A catalytic reaction is only possible if the metallic palladium can be reoxidized immediately. With gaseous oxygen, conditions to oxidize even finely divided palladium black are not optimal. However, metal salts such as cupric and ferric chlorides, chromates, heteropoly acids of phosphoric acid with molybdic and vanadic acids, or other oxidants - e. g., ben-zoquinone is used in kinetic investigations [10] - are suitable for reoxidation of the palladium metal. This fact explains the increase of the yield of acetaldehyde in the first experiments of the Consortium carried out in the presence of cupric and ferric chlorides, as mentioned above. [Pg.388]

Evidence for a tmns-cis isomerization of the OH ligand in complex 6 was revealed by a more detailed kinetic study of the reaction of ethylene with aqueous palladium chloride at low chloride ion concentration. It was demonstrated that H" " and Cl ions were found to both impede and accelerate the reaction, depending on their concentrations. From these studies, empirical rate Eq. (9.11) for constant ethylene concentration was derived [18], which transmutes into Henry s rate Eq. (9.5) at higher H" and Cl concentrations. [Pg.142]

Oxidation of terminal olefins to methyl ketones by aqueous palladium chloride and oxygen is very slow, but addition of micellar sodium lauryl sulphate increases the rate of formation of 2-octanone from 1-octene twentyfold at 50 °C. There is weaker catalysis by the non-ionic surfactant Brij-35 and inhibition by cationic surfactants. " Oxidation of diosphenol (35) in basic aqueous tetradecyltrimethylammonium chloride is faster and more effective than in water, giving a higher yield of (36). Two attempts at effecting the enantioselective reduction of aromatic ketones, one in micelles of R-dodecyl-dimethyl-a-phenylethylammonium bromide and the other in sodium cho-late micelles, both give optical yields of less than 2%. Rather more success was obtained in the catalysed oxidation of L-Dopa, 3,4-dihydroxyphenyI-alanine. In the presence of the Cu complex of N-lauroyl-L-histidine in cetyl-trimethylammonium bromide micelles reaction was 1.42 (pH 6.90, 30 °C) to... [Pg.200]

An interesting process for the production of acetaldehyde was based on the work of F. C. Phillips, who showed that ethylene could be oxidized to acetaldehyde by an aqueous palladium chloride solution. The palladium chloride was reduced to metallic palladium. During the late 1950 s, Wacker Chemie introduced a new process for the manufacture of acetaldehyde by direct oxidation of ethylene with air. The palladium metal was converted back to (PdCU) by an acidic solution of cupric chloride, which was, itself, reduced to cuprous chloride. The cupric chloride was regenerated by reaction with air in hydrochloric acid solution. The reaction sequence is shown in the following equations ... [Pg.303]

The palladium chloride process for oxidizing olefins to aldehydes in aqueous solution (Wacker process) apparendy involves an intermediate anionic complex such as dichloro(ethylene)hydroxopalladate(II) or else a neutral aqua complex PdCl2 (CH2=CH2)(H2 0). The coordinated PdCl2 is reduced to Pd during the olefin oxidation and is reoxidized by the cupric—cuprous chloride couple, which in turn is reoxidized by oxygen, and the net reaction for any olefin (RCH=CH2) is then... [Pg.171]

According to Skita, the reaction proceeds in a different manner if the reduction be effected with palladium chloride and hydrogen. In this case the citral in alcoholic solution is mixed with an aqueous solution of palladium chloride and the whole thickened with gum-arabic. Hydrogen gas is then forced into this solution under pressure. The products of the reduction include citronellal and citronellol and a di-molecular aldehyde, C Hj O, which probably has the following constitution —... [Pg.185]

B. 2-(4-Methoxyphenyl)-2-cyclohexen-1-one. A 500-mL, round-bottomed flask, equipped with a 1.5-in. Teflon-coated magnetic stirring bar and an argon inlet adaptor, is charged with 10.02 g (45.1 mmol) of 2-iodo-2-cyclohexen-1-one, 10.69 g (70.4 mmol, 1.56 eq) of 4-methoxyphenylboronic acid (Note 8), 16.72 g (72.1 mmol, 1.6 eq) of silver(l) oxide (Ag20) (Note 9), 0.85 g (2.8 mmol, 6 mol %) of triphenylarsine (Note 10), 0.53 g (1.4 mmol, 3 mol %) of palladium(ll) bis(benzonitrile)dichloride (Note 11), 200 mL of tetrahydrofuran (THF) and 25 mL of water (Note 12). The reaction mixture, flushed with argon, is stirred for 1 hr and then quenched by the addition of 125 mL of saturated aqueous ammonium chloride. After the solution is stirred for 1 hr, the... [Pg.36]

The catalyst is the key to this reaction and in this case is an aqueous solution of palladium chloride (PdCl2) and cupric chloride (CuCh). There is a complex, but well understood, mad scramble of ions and molecules that takes place as chlorine temporarily separates from the palladium and the copper and facilitates ethylene s reacting with oxygen. [Pg.234]

The oxidation of terminal olefins has been developed into a useful reaction for producing methyl ketones in good yields 6>. Again, cupric chloride and oxygen are employed to allow the palladium chloride to be used in only catalytic amounts. The method uses aqueous dimethylform-amide as solvent and a reaction temperature of 65° C. [Pg.10]

To a mixture of the iodonium salt (172 mg, 0.46 mmol) and palladium acetate (4 mg, 5 mol%) was added sodium bicarbonate (77 mg, 0.92 mmol) followed by the cyclic carbonate (110 mg, 0.46 mmol) in DMF (5 ml), under nitrogen, at room temperature. After stirring for 2 h, the reaction mixture was quenched with saturated aqueous ammonium chloride solution and extracted with ether (2 x 20 ml). The extract was dried, the solvent removed and the residue chromatographed on silica (ethyl acetate-hexanes 1 4) to afford 4-phenylvinyl-5-benzyloxymethyl-1,3-dioxol-2-one (140 mg, 97%), m.p. not given. [Pg.142]

To a stirred mixture of the iodonium salt (197 mg, 0.5 mmol), palladium acetate (5.6 mg) and sodium bicarbonate (420 mg, 5 mmol) in DMF (2 ml) was added butenone (17.5 mg, 2.5 mmol), under argon, at room temperature. After 2 h, precipitation of palladium black was observed then, saturated aqueous ammonium chloride was added to the reaction mixture, followed by extraction with ethyl acetate. The organic layer was dried, the solvent evaporated and the residue purified by flash chromatography (hexanes-ethyl acetate) to give trans, trans-6-phenyl-hexa-3,5-diene-2-one (63 mg, 73%), m.p. not given. [Pg.164]

Mix a drop of the test solution on drop-reaction paper with a drop of a 1 per cent aqueous solution of palladium chloride. A brownish-black precipitate forms. [Pg.332]

Oxidation of Ethylene. In 1894 F. C. Phillips observed the reaction of ethylene [74-85-1] in an aqueous palladium(II) chloride solution to form acetaldehyde. [Pg.51]

A sample of activated carbon having high adsorptive capacity is warmed with dilute aqueous nitric acid. The resulting mixture is filtered, washed with water until free of acid, and dried at 200°. Twelve grams of the treated carbon, 8 g. of palladium chloride, and 24 ml. of commercial formalin are mixed thoroughly and treated with 48 ml. of 50% aqueous potassium hydroxide solution. The reaction mixture is held below room temperature during this operation. The solid obtained is removed by filtration, washed with water until free of alkali, and then dried at 120°. The resulting catalyst contains about 30% palladium. [Pg.251]

If eq. (6), derived by Ninomiya et al. [24] by studying the reaction of ethylene with palladium chloride in a mixture of acetic acid and p-xylene, is transformed by replacing [NaOAc] with 1/[H, it adopts the form of eq. (13) of Section 2.4.1 [25], showing an activating or an inhibiting effect of ions at low or higher concentrations, respectively. A similar behavior of CF ions, also shown in the equation mentioned, was observed by van Helden et al. [26]. Clark et al. [27] published a rate equation (eq. (7)) quite similar to that of the Wacker reaction in aqueous system (see eq. (9) in Section 2.4.1). [Pg.1325]

The selectivity of palladium and gold for alkene oxidation to aldehydes 28,29,170) was attributed initially to adsorption strength. However, electrooxidation in the presence of palladium ions indicates possible homogeneous alkene insertion, similar to the Wacker process 304). Homogeneous reaction is also involved in redox oxidations of hydrocarbons. In this case, the nature of the metal ions is expected to control selectivity. Indeed, toluene yields 20% benzaldehyde in electrolytes containing Ce salts, while oxidation proceeds to benzoic acid with Cr redox catalysts 311). In addition, the concentration of redox catalysts appears to affect yields in nonelectrochemical oxidation of ethylene large amounts of palladium chloride promote butene formation at the expense of acetaldehyde 312). Finally, the role of the electrolyte and solvent should not be ignored. For instance, electrooxidation of ethylene on carbon, in aqueous solution of acetic acid yields acetaldehyde 313) in the... [Pg.282]

Butyllithium (9.5 mL, 15 mmol, 1.6 M solution in hexane) was added to a solution of furan (1.1 mL, 15 mmol) in THF (15 mL) at 0 °C. After stirring at 0 °C for 1 h and room temperature for 1 h, the yellow solution was slowly transferred via cannula into a solution of zinc chloride (15 mL, 15 mmol, 1 M solution in Et20) at 0°C. The mixture was stirred for 1 h at 0 °C and then added to a solution of l-bromo-2-iodobenzene (1.3 mL, 10 mmol) and bistriphenylphosphine palladium chloride (0.21 g, 0.3 mmol) in THF (2 mL). After stirring for 12 h at room temperature, the reaction was added to IM HCl aqueous solution (10 mL) and the product was extracted into ether and washed with saturated aqueous sodium bicarbonate solution. The ether solution was dried (MgS04) and the solvent was removed in vacuo. The crude material was purified by flash chromatography (hexane) to give 2.10 g (95%) of the l-bromo-2-(2 -furyl)-benzene 5.3a as a colorless oil. [Pg.271]

On balance, palladium offers the best combination of activity and selectivity at reasonable cost, and for these reasons has become the basis of the most successful commercial alkyne hydrogenation catalysts to date. Because of their inherently high activity, these catalysts contain typically less than 0.5 % (by weight) of active metal-to preserve selectivity at high alkyne conversion. Despite the prominence of these catalysts, other active metals are used in fine chemicals applications. Of particular utility is the nickel boride formulation formed by the action of sodium borohydride on nickel(II) acetate (or chloride). Reaction in 95 % aqueous ethanol solution yields the P2-Ni(B) catalyst and selectivity in alkyne semi-hydrogenation has been demonstrated in the reaction of 3-hexyne to form cw-3-hexene in 98 % yield [15,16] ... [Pg.354]

Kinetic studies 93> on the oxidation of olefins by aqueous palladium(II) chloride have yielded several equlibrium constants for the reaction ... [Pg.109]

Acetaldehyde is produced by the liquid phase oxidation of ethylene in the presence of a palladium chloride-cupric chloride catalyst. The reaction takes place in aqueous solution at approximately 125-130°C (255-265°F). It is carried out either as a one-step process using high purity oxygen or as a two-step process using air as the source of oxygen to reoxidize the catalyst in a separate reactor. [Pg.160]

Terminal acetylenes 268 (R = Bu, /-Bu or Ph) react with the lithium silylcuprate 269 by cw-addition to afford, after work-up with aqueous ammonium chloride, the silylated olefins 270 A similar reaction of 1-dodecyne with the reagent prepared from methylmagnesium iodide and lithium (dimethyl)phenylsilane and a trace of tris(tributylphosphine)platinum(II) chloride gave solely the ( )-alkene 271. In contrast, in the presence of bis(tri-o-tolylphosphine)palladium(II) chloride the regioisomer 272 was the main product. ... [Pg.320]

The electrophilic substitution is the most characteristic reaction for these classes of compounds. Compound (21) undergoes standard electrophilic aromatic substitution reactions. Thus it forms the 6-bromo compound (58) with A7-bromosuccinimide and 6,7-dibromo compound (72) with the excess of the same reagent. It also forms the 6-nitro compound (67) with copper(II) nitrate trihydrate and 6,7-dinitro compound (68) with excess of nitronium tetrafluoroborate. The bis(trifluoro-acetoxy)thallium derivative (73) was formed from trithiadiazepine (21) and thallium(III) trifluoro-acetate in refluxing acetonitrile. Without isolation, (73) was directly converted into the pale yellow 6-iodo compound (74) with aqueous potassium iodide, into the 6-cyano compound (75) with copper(I) cyanide, and into methyl trithiadiazepine-6-carboxylate (76) with carbon monoxide and methanol in the presence of palladium chloride, lithium chloride, and magnesium oxide. Compound (21) is acetylated in the presence of trifluoromethanesulfonic acid (Scheme 7) <85CC396,87JCS(P1)217, 91JCS(P1)2945>. [Pg.381]

I. V. Kozhevnikov, V. E. Taraban ko, and K. I. Matveev [Kinet. Catal., 21, 679 (1980)] have studied the oxidation of isopropanol by palladium chloride in aqueous solution over the temperature range 339 to 369 K. The stoichiometry of the reaction is... [Pg.104]


See other pages where Aqueous Palladium Chloride Reactions is mentioned: [Pg.391]    [Pg.139]    [Pg.81]    [Pg.69]    [Pg.169]    [Pg.149]    [Pg.139]    [Pg.213]    [Pg.151]    [Pg.57]    [Pg.102]    [Pg.102]    [Pg.81]    [Pg.411]    [Pg.411]    [Pg.714]    [Pg.433]    [Pg.153]    [Pg.101]    [Pg.509]   


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