Palladium iodide

To date, a few methods have been proposed for direct determination of trace iodide in seawater. The first involved the use of neutron activation analysis (NAA) [86], where iodide in seawater was concentrated by strongly basic anion-exchange column, eluted by sodium nitrate, and precipitated as palladium iodide. The second involved the use of automated electrochemical procedures [90] iodide was electrochemically oxidised to iodine and was concentrated on a carbon wool electrode. After removal of interference ions, the iodine was eluted with ascorbic acid and was determined by a polished Ag3SI electrode. The third method involved the use of cathodic stripping square wave voltammetry [92] (See Sect. 2.16.3). Iodine reacts with mercury in a one-electron process, and the sensitivity is increased remarkably by the addition of Triton X. The three methods have detection limits of 0.7 (250 ml seawater), 0.1 (50 ml), and 0.02 pg/l (10 ml), respectively, and could be applied to almost all the samples. However, NAA is not generally employed. The second electrochemical method uses an automated system but is a special apparatus just for determination of iodide. The first and third methods are time-consuming. 

Keywords Alkenes Alkynes CO building block Lactonization Palladium iodide... 

The reaction of alcohols with CO can also be catalysed by palladium iodides, and various ligands or solvents. Acetic acid is prepared by the reaction of MeOH with CO in the presence of a catalyst system comprising a palladium compound, an ionic iodide compound, a sulfone solvent at conditions similar to those of the rhodium system (180 °C, 60 bar), and, in some cases, traces of a nickel-bipyridine compound were added. Sulfones or phosphine oxides play a stabilising role in preventing metal precipitation [26], Palladium(II) salts catalyse the carbonylation of methyl iodide in methanol to methyl acetate in the presence of an excess of iodide, even without amine or phosphine co-ligands platinum(II) salts are less effective [27],... 

Dihydro derivatives are readily formed in reactions with aldehydes and ketones, and aldehyde addition products can be dehydrogenated to the fully conjugated heterocycles <1981RCR816, 1995AQ151>. In a new procedure, palladium iodide-catalyzed carbonylation of 1,8-naphthalenediamine 918 gave 2(l//)-perimidinone 921 in 91% yield <2004JOC4741>. 

A solution of tetrammino-palladium iodide is first prepared, and on evaporation or treatment with acid it partially decomposes, and deposits a substance which is sometimes an orange crystalline body and sometimes a yellow amorphous substance, both of which have the same composition. 

All metallic iodides except silver iodide, mercurous iodide, mercuric iodide, lead iodide, cuprous nidide. thallium iodide, and palladium iodide, are soluble. The iodides of antimony, bismuth, tin require a little free acid to keep them in solulion. 

The highest yields for this reaction were obtained with an unsubstituted amide and with one containing a p-chloro substituent, with vinyl methyl ketone as the alkene. Use of styrene led to lower yields. The reaction of the intermediate aceta-nilidopalladacycle with methyl iodide, which produces N-o-tolylacetamide is interesting mechanistically [7b], Stoichiometrically, full conversion was achieved, but attempts with catalysts gave only 10 turnovers and required the use of silver acetate to convert palladium iodide into the acetate, because palladium iodide does not have enough activity for metalation. 

Reliable Sample for Radiation Detection. The sample must be prepared for counting by an effective method. Many such methods have been published, each appropriate for its element. For example, strontium may be prepared for counting as strontium oxalate or carbonate, and iodine as silver or palladium iodide. Samples submitted for mass spectrometric analysis must be in a form that is suitably volatilized and processed by the instrument. 

To determine the concentration of 131I in drinking water by purification sequentially as silver iodide and palladium iodide, followed by counting beta particles. 

The first step of the analysis ensures isotopic exchange of the stable carrier and the radio-iodine in the sample. In this experiment, iodate carrier is added and then reduced to iodide with sodium sulfite to cause exchange among iodate, iodine, and iodide species. (Read the discussion in the Introduction to the Course on isotopic exchange.) The resulting iodide is purified by precipitation, first as silver iodide (Agl) and then, after dissolution, as palladium iodide (Pdl2). 

The mechanism can be rationalized as follows (Scheme 76). Palladium iodide triggers the carbonylation of the propargyl amine to give an 2-alkynyl carbamate-Pd-iodide complex that inserts the triple bond to give a syn-vinyl-... 

The detection and quantitative determination of iodine in high concentrations is possible by precipitation of yellow silver iodide, black palladium iodide, and yellow or red mercuric iodide and determination in acidic aqueous solutions by titrating with a standard solution of sodium thiosulfate using starch as the indicator. An alternative... 

Pdl2 PALLADIUM IODIDE 1314 PuOl PLUTONIUM IODIDE OXIDE 1356... 

The oxidative addition of an aryl iodide to a zerovalent complex such as [Pd(PPh3)4] gives tra s-[Pd(Ar)I(PPh3)2] having a palladium-aryl and a palladium-iodide bond indeed, this is one of the oldest examples of oxidative addition of aryl iodide to Pd(0) complex (Eq. 1.1) [10]. 

The radionuclide with added carrier can be separated from most other long-lived radionuclides by precipitating silver or palladium iodide from dilute niuic acid solution. As indicated in Section 6.3.1, the oxidation state of radioiodine, of which there are several, must be well defined before a separation step can be trusted. Other purification techniques are solvent extraction of iodine oxidized to h into carbon tetrachloride followed by back extraction of the reduced iodide form into water, or sorption of 1 on anion-exchange resin followed by elution with a strong chloride solution (Kleinberg and Cowan 1960). These processes also lend themselves to concentrating the radionuclide from larger solution volumes to attain a lower detection limit. 

Fission products may contain the iodine isotopes from to Of these, is considered the most significant hazard in drinking water. Three methods are available for the determination of radioactive iodine in water samples precipitation, sorption on an anion-exchange resin, and distillation. The precipitation method is preferred because it is simple and requires the least time. In the precipitation method, iodate carrier is added to the sample and reduced to iodide with sodium sulfite. The iodide is precipitated as silver iodide. The precipitate is dissolved, and purified with zinc powder and sulfuric acid. The iodide is finally precipitated as palladium iodide, Pdli, for counting in a low-background //-counter, or ///y coincidence system. 

It was found, however, that if palladium iodide is used in place of the base under oxidative conditions under CO + CO2 pressure the following reaction occurs (Scheme 37). 

Ethylene reacts with carbon monoxide and water in the presence of nickel carbonyl to give propionic acid in high yield. If care is taken to maintain a high concentration of propionic acid in the reaction mixture and the temperature, which is normally 300 in the propionic acid synthesis, is decreased to 240 °C propionic acid anhydride is formed in high yield in the presence of Ni(CO)4. Propionic acid ethyl ester is the main product in the reaction of ethylene, carbon monoxide and water (low water concentration must be applied) with cobalt carbonyls instead of Ni(CO)4. The conversion of ethylene with carbon monoxide in dilute alkaline medium with the aid of potassium nickel cyanide gives propionyl propionic acid [403-405]. At higher temperatures and without pH correction in the same reaction mainly polyketones with the sequences -(CHg-CHg-CO)- are formed. If the reaction is carried out in absence of water or alcohols and in presence of palladium iodide as catalyst, a mixture of hexenolide isomers is the main product. Colorless polyketones of the same structure are obtained if an excess of ethylene is treated with carbon monoxide in the presence of complex palladium salts as catalysts in an alcoholic hydrogen halide solution at 100 °C and 700 atm [406]. 

When alkali iodides are added to solutions of palladium salts, the initial brown-black precipitate of palladium iodide dissolves in excess iodide to yield red-brown complex tetraiodopalladium ions ... 

Because of the low solubility product of palladium iodide, water suspensions of difl cultly soluble metal iodides, such as CU2I2 (white), Agl (yellow) and Hgl2 (red), also react with Pd+ ions. Because of the low iodide concentration available, these reactions proceed only to the formation of insoluble Pdl as shown in (1) there is no production of soluble [PdlJ- ions as shown... 

A drop of a 2 % alcoholic solution of iodine is placed on the foil being tested and allowed to evaporate in the air. If palladium is present, a brown-black fleck is left due to the formation of palladium iodide. It withstands washing with water, alcohol, acetone or ether. The stain disappears on heating to redness the palladium iodide decomposes with evolution of iodine. Solutions of alkali iodides likewise discharge the stain formation of [Pdl J ions. Palladium that has been electrolytically deposited on metals... 

PABA palladium iodide ester cetilico del acido pantothenic acid... 

In a similar transformation, oxidative aminocarbonylation of alkyl- and aryl-substituted 1-alkynes is catalyzed by Pdl2/KI under relatively mild conditions to afford 2-ynamides 64 in good yield (Scheme 10.20) [60]. Nucleophilic secondary amines were required as amines of low basicity were unreactive and primary amines gave complex reaction mixtures. The key intermediate in the mono-aminocarbonylation was proposed to be an alkynyl palladium iodide that undergoes CO insertion followed by nucleophilic abstraction by amine to generate the product and Pd(0), which is reoxidized by iodine (2HI + I/2O2 = I2 + H2O). Small amounts of diaminocarbonylation product (maleic... 

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