Palladium chlorine with

In the reduction of p-chlorocinnamic acid with an excess of sodium hypophosphite and palladium (equation 47), the double bond is saturated and the hydrogenolysis of chlorine occurs. With one equivalent of the hypophosphite, only saturation of the double bond takes place, and p-chlorohydrocinnamic acid is obtained after 1.5 h. ... 

Many different catalytic systems based on palladium with various cocatalysts and supports were studied. The nature of the support influences the catalyst performance it is important to avoid the presence of both acid sites, to avoid MN decomposition to methylformate and methylal, and basic sites that increase the DM0 production. The catalyst must contain chloride anions to be effective and to keep the oxidation state of palladium(II). Therefore, the loss of chlorides in the outlet stream of the reactor as organic or inorganic compounds must be counteracted by addition of chlorinated organic compounds or HCl in the feed, to maintain the catalyst performances. 

The anion PdfC H lCl is the palladium analogue of Zeise s anion (p. 196). Substitution of Cl" by water occurs trans to ethene rather than to chlorine, consistent with the greater trans effect of the former. The next step is thought to be nucleophilic attack of water on the ethene complex. Hydroxide cannot be the nucleophile as its concentration is too low under the prevailing acid conditions to account for the observed rate. There is still some controversy whether the... 

Similarly, Feeley and Sachtler [256] showed that cation exchange of solid palladium with H-Y was mediated by an oxidative gas phase. These authors assumed that PdCl2 formed from Pd and chlorine and that PdCl2 subsequently diffused into the pore system, reacted there and replaced the protons under formation of Pd + on cation positions and HCl. 

The coupling reaction of chlorinated biphenyls with Grignard reagents RMgX is catalyzed by [NiCl2(dppp)] and the rate increases in the series R = Me < Et < Bu" < Ph. Diethylether is necessary for the reactions palladium complexes are inactive. The first alkylation step of 3,5,4 -tri-... 

In a related process, 1,4-dichlorobutene was produced by direct vapor-phase chlorination of butadiene at 160—250°C. The 1,4-dichlorobutenes reacted with aqueous sodium cyanide in the presence of copper catalysts to produce the isomeric 1,4-dicyanobutenes yields were as high as 95% (58). The by-product NaCl could be recovered for reconversion to Na and CI2 via electrolysis. Adiponitrile was produced by the hydrogenation of the dicyanobutenes over a palladium catalyst in either the vapor phase or the Hquid phase (59,60). The yield in either case was 95% or better. This process is no longer practiced by DuPont in favor of the more economically attractive process described below. 

Use of mercuric catalysts has created a serious pollution problem thereby limiting the manufacture of such acids. Other catalysts such as palladium or mthenium have been proposed (17). Nitration of anthraquinone has been studied intensively in an effort to obtain 1-nitroanthraquinone [82-34-8] suitable for the manufacture of 1-aminoanthraquinone [82-45-1]. However, the nitration proceeds so rapidly that a mixture of mono- and dinitroanthraquinone is produced. It has not been possible, economically, to separate from this mixture 1-nitroanthraquinone in a yield and purity suitable for the manufacture of 1-aminoanthraquinone. Chlorination of anthraquinone cannot be used to manufacture 1-chloroanthraquinone [82-44-0] since polychlorinated products are formed readily. Consequentiy, 1-chloroanthraquinone is manufactured by reaction of anthraquinone-l-sulfonic acid [82-49-5] with sodium chlorate and hydrochloric acid (18). 

Catalytic Oxidation. Catalytic oxidation is used only for gaseous streams because combustion reactions take place on the surface of the catalyst which otherwise would be covered by soHd material. Common catalysts are palladium [7440-05-3] and platinum [7440-06-4]. Because of the catalytic boost, operating temperatures and residence times are much lower which reduce operating costs. Catalysts in any treatment system are susceptible to poisoning (masking of or interference with the active sites). Catalysts can be poisoned or deactivated by sulfur, bismuth [7440-69-9] phosphoms [7723-14-0] arsenic, antimony, mercury, lead, zinc, tin [7440-31-5] or halogens (notably chlorine) platinum catalysts can tolerate sulfur compounds, but can be poisoned by chlorine. 

The exocyclic C — C double bond in the chlorin can be reduced by catalytic hydrogenation in tetrahydrofuran/water in the presence of palladium(II) acetate with triethoxysilane as hydrogen source to yield under kinetic control cw-stereoisomers, which can be transformed by treatment with /)-toluenesulfonic acid in methanol to the thermodynamically favored trans-isomers.27d... 

The dechlorination of the C-3 and C-5 position of the pyrazinone system was described to be fast under microwave irradiation [29]. Contrary to the reported de-chlorination [26] via palladium-catalyzed reaction with sodium formate 100 °C for 2-4 h and at the C-5 position in 2-3 days, a dramatic rate enhancement was observed under microwave irradiation (Scheme 12). The mono-reduction at C-3 was performed at 190 °C in DMF in merely 5 min, and the reduction of C-5, starting from the mono-reduction product, was performed in n-butanol in 55 min to afford the fois-reduction product in good overall yield. 

With the growing prominence of the petrochemicals industry this technology was, in turn, replaced by direct air oxidation of naphtha or butane. Both these processes have low selectivities but the naphtha route is still used since it is a valuable source of the co-products, formic and propanoic acid. The Wacker process, which uses ethylene as a feedstock for palladium/copper chloride catalysed synthesis of acetaldehyde, for which it is still widely used (Box 9.1), competed with the direct oxidation routes for a number of years. This process, however, produced undesirable amounts of chlorinated and oxychlorinated by-products, which required separation and disposal. 

Rare, shiny, and lightest metal of the platinum group. Hardens platinum and palladium. The presence of 0.1 % of ruthenium in titanium improves its resistance to corrosion 100-fold. The spectacular catalytic properties of ruthenium are used on industrial scales (hydrogenations, sometimes enan-tioselective, and metathesis). Titanium electrodes coated with ruthenium oxide are applied in chlorine-alkaline electrolysis. Suitable for corrosion-resistant contacts and surgical instruments. 

Comparing the spectra of Pd-45 and Pd-105 with those of Pd-115 and Pd-190, respectively, we see that in the samples prepared from palladium acetate the 1982 cm-1 band is absent, or at any rate strongly reduced in intensity. Hence, it is not impossible that the 1982 cm-1 band is due to CO adsorbed on a palladium surface that is partially covered with chlorine. 

Additional publications from Sanford et al. describe the full exploration of palladium-catalyzed chelate-directed chlorination, bromination, and iodination of arenes using N-halosuccinimides as the terminal oxidant <06T11483>. Moreover, an electrophilic fluorination of dihalopyridine-4-carboxaldehydes was reported by Shin et al. <06JFC755>. This was accomplished via transmetalation of the bromo derivative, followed by treatment with A-fluorobenzenesulfinimide as the source of electrophilic fluorine. 

The use of 1,6-diene systems usually does not result in cyclization reactions with palladium ) salts. For example, with 1,6-heptadiene a /i-elimination takes place from the cqjr-intermediate to give diene 22 as the major product (equation 10)27. However, more recently Trost and Burgess21 have shown that with a 4,4-bis(phenylsulfonyl) derivative of 1,6-heptadiene (23) an insertion takes place to give a 5-membered ring product (24, equation 11). The final step of the latter reaction is oxidative cleavage of the palladium-carbon bond by CuCl2 to produce a carbon-chlorine bond. 

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