Chloroform, palladium complexes with

Dimethylglyoxime. The complexes with nickel and with palladium are soluble in chloroform. The optimum pH range for extraction of the nickel complex is 4-12 in the presence of tartrate and 7-12 in the presence of citrate (solubility 35-50 fig Ni mL 1 at room temperature) if the amount of cobalt exceeds 5 mg some cobalt may be extracted from alkaline solution. Palladium(II) may be extracted out of ca lM-sulphuric acid solution. 

Terminal allenes.1 A synthesis of 1,2-dienes (3) from an aldehyde or a ketone involves addition of ethynylmagnesium bromide followed by reaction of the adduct with methyl chloroformate. The product, a 3-methoxycarbonyloxy-l-alkyne (2), can be reduced to an allene by transfer hydrogenolysis with ammonium formate catalyzed by a zero-valent palladium complex of 1 and a trialkylphosphine. The choice of solvent is also important. Best results are obtained with THF at 20-30° or with DMF at 70°. 

Addition of arylboronic acids to a,/3-unsaturated ketones can be catalysed by palladium(0)-phosphine complexes with chloroform in the presence of a base. 

Aryl triphenylstannyl tellurium reacted with 1,5-cyclooctadienedichloropalladium in chloroform at 20°. With equimolar amounts of the reagents 1,5-cyclooctadienechloro (arenetellurolato)palladiums were isolated with 2 moles of tellurium compound per mole of palladium complex, 1,5-cyclooctadiene bis[arenetellurolato]palladiums were obtained2. 

Many alkenes will react with PdCl2, forming a itt-allyl complex and one mole of HCl. A base is normally added to react with the HCl produced. Solvents that have proven useful include acetic acid, chloroform, methanol, and DMF. Where isomeric itt-allyl palladium complexes can be formed, one often obtains a mixture of products. This is particularly true for reactions run in acetic acid. The addition of CUCI2 causes an increase in regioselectivity, resulting in abstraction of the allylic C-H bond that leads to the more-substituted Tr-aUyl complex (equation 53). 

Dipalladium(II) complexes with N,0-bridging ligands, mhp and chp, were prepared by reaction of palladium(II) acetate with Na(mhp) or Na(chp) in dichloromethane (82, 82). Recrystallization of the former from methanol gives the fnms-isomer exclusively. However, recrystallization from chloroform gives a sample containing the cis-isomer. 

Aryl, vinyl, and benzyl halides are catalytically carbonylated by CO generated in situ from chloroform and aqueous alkali, in the presence of phosphine-palladium complexes such as PdCl2(PPh3)3. The biphasic reactions do not require a PT agent, they occur at r.t., and they afford the corresponding carboxylic acids in up to 92% yield. Labeling experiments with CHCb showed that the source of the Cl unit in the carbonylation is chloroform... 

The experimental results and the known facility of O-desilylation of silyl enol ethers, such as 3-acetoxy-2-trimethylsiloxypropenes, under the given reaction conditions led Trost ° to suggest the intermediacy of an oxatrimethylenemethanepalladium complex 4 addition to the alkene at the less-substituted terminal carbon atom of 4 followed by tautomerism and ring closure would give rise to the cyclopropane. Since the palladium complex that is prepared from tris(dibenzylideneacetone)palladium(0)-chloroform complex [Pd2(dba)j CHClj] and triphen-ylphosphane also catalyzes the Brook rearrangement of an a-silyl ketone to a silyl enol ether, (2-oxo-3-silylpropyl) acetates can also serve as precursors of intermediate palladium complexes 4, and the same cyclopropanation reactions as with 3-acetoxy-2-trimethylsiloxypropenes can be carried out. 

The chelated metal ion does not seem to affect the pathway of the nitration reactions, but does have an effect on their course. The reaction of nickel(II) acetylacetonate with nitrous acid in water, ethanol, or ethanol-water solutions in the presence of ammonium acetate gave a red compound, N CsHjNsChK which was diamagnetic, monomeric in chloroform solution, and a nonelectrolyte in nitrobenzene. A similar compound was obtained with Pd(II), and the presence of ammonia was found to be essential for the formation of these two compounds. The corresponding compounds of Cu(II) and Pt(II) could not be prepared under the same experimental conditions. The infrared spectra of the nickel and palladium complexes are compatible with the two structures (XII) and (XIII), and on this evidence... 

Arsonium salts have found considerable use in analytical chemistry. One such use involves the extraction of a metal complex in aqueous solution with tetraphenyiarsonium chloride in an organic solvent. Titanium(IV) thiocyanate [35787-79-2] (157) and copper(II) thiocyanate [15192-76-4] (158) in hydrochloric acid solution have been extracted using tetraphenyiarsonium chloride in chloroform solution in this manner, and the Ti(IV) and Cu(II) thiocyanates deterrnined spectrophotometricaHy. Cobalt, palladium, tungsten, niobium, and molybdenum have been deterrnined in a similar manner. In addition to their use for the deterrnination of metals, anions such as perchlorate and perrhenate have been deterrnined as arsonium salts. Tetraphenyiarsonium permanganate is the only known insoluble salt of this anion. 

The reaction is a sensitive one, but is subject to a number of interferences. The solution must be free from large amounts of lead, thallium (I), copper, tin, arsenic, antimony, gold, silver, platinum, and palladium, and from elements in sufficient quantity to colour the solution, e.g. nickel. Metals giving insoluble iodides must be absent, or present in amounts not yielding a precipitate. Substances which liberate iodine from potassium iodide interfere, for example iron(III) the latter should be reduced with sulphurous acid and the excess of gas boiled off, or by a 30 per cent solution of hypophosphorous acid. Chloride ion reduces the intensity of the bismuth colour. Separation of bismuth from copper can be effected by extraction of the bismuth as dithizonate by treatment in ammoniacal potassium cyanide solution with a 0.1 per cent solution of dithizone in chloroform if lead is present, shaking of the chloroform solution of lead and bismuth dithizonates with a buffer solution of pH 3.4 results in the lead alone passing into the aqueous phase. The bismuth complex is soluble in a pentan-l-ol-ethyl acetate mixture, and this fact can be utilised for the determination in the presence of coloured ions, such as nickel, cobalt, chromium, and uranium. 

Reaction of siloxycyclopropane 1 with acid chlorides in the presence of a palladium catalyst also proceeds cleanly to give 4-ketoesters in high yields (Eq. 59, Table 14) [57]. Chloroform is a suitable solvent. Kinetic studies have revealed that the interaction between 1 and an acylpalladium chloride complex is the rate limiting step. 

It is remarkable that the palladium(O) complexes are inactive in the absence of chloroform.236 Palladium acetate-bipyridine complex has been reported to catalyse conjugate addition of arylboronic acids to a -unsaturated carbonyl compounds in aqueous media with high yields.237... 

The complexes (l,5-cyclooctadiene)(2,4-pentanedionato)-palladium(II) and platinum(II) tetrafluoroborate are air-stable solids, soluble in polar organic solvents such as chloroform, methylene chloride, acetonitrile, acetone, or methanol but insoluble in nonpolar solvents such as alkanes, benzene, or ether. Their solutions in acetone have conductivities typical of 1 1 electrolytes. Their proton magnetic resonance spectra (in CDC13 solutions, internal tetramethylsilane reference at 60 MHz.) show peaks due to coordinated cyclooctadiene at 3.78 and 6.7-7.4r (Pd) and at 4.25 and 6.9-7.6r (Pt) and due to the chelated /3-diketone at 4.39 and 7.88r (Pd) and at 4.15 and 7.81r (Pt) with the expected area ratios. In the spectrum of the platinum compound coupling with the 95Pt isotope (33 %... 

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