Iodides sulfur oxides

The radioactive isotopes available for use as precursors for radioactive tracer manufacturing include barium [ C]-carbonate [1882-53-7], tritium gas, p2p] phosphoric acid or pP]-phosphoric acid [15364-02-0], p S]-sulfuric acid [13770-01 -9], and sodium [ I]-iodide [24359-64-6]. It is from these chemical forms that the corresponding radioactive tracer chemicals are synthesized. [ C]-Carbon dioxide, [ C]-benzene, and [ C]-methyl iodide require vacuum-line handling in weU-ventilated fume hoods. Tritium gas, pH]-methyl iodide, sodium borotritide, and [ I]-iodine, which are the most difficult forms of these isotopes to contain, must be handled in specialized closed systems. Sodium p S]-sulfate and sodium [ I]-iodide must be handled similarly in closed systems to avoid the Uberation of volatile p S]-sulfur oxides and [ I]-iodine. Adequate shielding must be provided when handling P P]-phosphoric acid to minimize exposure to external radiation. 

On treatment of a solution of the pyrido[l,2-a]pyrimidinium salt (16) with potassium permanganate in 2 N sulfuric acid, 11% 2-aminopyridine, 1% 4-oxo-4H-pyrido[l,2-a]pyrimidine, and traces of 2-nitropyridine were isolated from the reaction mixture.9 When 2,4-dimethylpyrido[l,2-a]-pyrimidinium iodide was oxidized with aqueous potassium permanganate at 50-60°C, 2-acetamidopyridine was obtained in 65% yield.2... 

Hydrogen chloride is not very soluble in sulfuric acid but probably reacts to some extent to give chlorsulfonic acid. Hydrogen bromide and iodide are oxidized to their respective elements. Even perchloric acid, which is often regard as the strongest known acid, shows little or no... 

Sodium thiosulfate cannot be directly titrated with potassium permanganate because a mixture of tetrathionate and sulfate ions is formed. The titration is indirect. Potassium iodide is oxidized by permanganate ions in sulfuric acid medium. The liberated iodine is titrated with thiosulfate. Let s recall that the used thiosulfate solution must have been quite recently standardized. 

One method which gave a purification of iodine-131 from a 16-day-old solu-tion of 10 fissions had the following steps (224). Iodide, iodate, or periodate carrier and sodium chlorate were added to the sample which contained only inorganic substances (but no gold) and no reducing agents. The solution was made 6-10 in hydrochloric acid in order to produce iodine monochloride (yellow-green solution). The monochloride was extracted into butyl acetate and then back-extracted into water as iodide by means of sulfurous acid. Iodide was oxidized to elemental iodine with iron(III) chloride in dilute sulfuric acid and the iodine extracted into toluene. The element was back-extracted into water as iodide by sulfurous acid and palladium(II) iodide was precipitated. 

In the distillation method, iodide carrier was added to the sample, an oxidation-reduction cycle was carried out, and molecular iodine was distilled into carbon tetrachloride. (In the oxidation-reduction cycle, iodide was oxidized to iodate by permanganate in sulfuric acid solution and any elemental bromine and chlorine activities formed were distilled off.) Iodine was back-extracted as iodide into water from the carbon tetrachloride by means of acid sulfite and silver iodide was precipitated. 

Seaweeds. The eadiest successful manufacture of iodine started in 1817 using certain varieties of seaweeds. The seaweed was dried, burned, and the ash lixiviated to obtain iodine and potassium and sodium salts. The first process used was known as the kelp, or native, process. The name kelp, initially apphed to the ash of the seaweed, has been extended to include the seaweed itself. About 20 t of fresh seaweed was used to produce 5 t of air-dried product containing a mean of 0.38 wt % iodine in the form of iodides of alkah metals. The ash obtained after burning the dried seaweed contains about 1.5 wt % iodine. Chemical separation of the iodine was performed by lixiviation of the burned kelp, followed by soHd-Hquid separation and water evaporation. After separating sodium and potassium chloride, and sodium carbonate, the mother Hquor containing iodine as iodide was treated with sulfuric acid and manganese dioxide to oxidize the iodide to free iodine, which was sublimed and condensed in earthenware pipes (57). 

The aHphatic iodine derivatives are usually prepared by reaction of an alcohol with hydroiodic acid or phosphoms trHodide by reaction of iodine, an alcohol, and red phosphoms addition of iodine monochloride, monobromide, or iodine to an olefin replacement reaction by heating the chlorine or bromine compound with an alkaH iodide ia a suitable solvent and the reaction of triphenyl phosphite with methyl iodide and an alcohol. The aromatic iodine derivatives are prepared by reacting iodine and the aromatic system with oxidising agents such as nitric acid, filming sulfuric acid, or mercuric oxide. 

The hberated iodine is measured spectrometricaHy or titrated with Standard sodium thiosulfate solution (I2 +28203 — 2 1 VS Og following acidification with sulfuric acid buffers are sometimes employed. The method requires measurement of the total gas volume used in the procedure. The presence of other oxidants, such as H2O2 and NO, can interfere with the analysis. The analysis is also technique-sensitive, since it can be affected by a number of variables, including temperature, time, pH, iodide concentration, sampling techniques, etc (140). A detailed procedure is given in Reference 141. 

Capture efficiency is the fraction of generated contaminant that is directly captured by the hood. Measurement of capture efficiency involves measuring concentration of process-generated contaminant or a tracer material. Using process-generated contaminant requires use of instruments suited to each specific contaminant and its conditions (temperature, pressure, concentration, form, etc.). In order to facilitate these measurements, a tracer is often substituted for the process-generated contaminant. The tracer is usually a gas (sulfur hexafluoride, nitrous oxide, helium, or similar), but an aerosol (particles) can also be used (potassium iodide, polystyrene particles, microbiological particles, etc.). The chosen tracer should be as similar to the real contaminant as possible, but at the same time should... 

Codeposition of silver vapor with perfluoroalkyl iodides at -196 °C provides an alternative route to nonsolvated primary perfluoroalkylsilvers [272] Phosphine complexes of trifluaromethylsilver are formed from the reaction of trimethyl-phosphme, silver acetate, and bis(trifluoromethyl)cadmium glyme [755] The per-fluoroalkylsilver compounds react with halogens [270], carbon dioxide [274], allyl halides [270, 274], mineral acids and water [275], and nitrosyl chloride [276] to give the expected products Oxidation with dioxygen gives ketones [270] or acyl halides [270] Sulfur reacts via insertion of sulfur into the carbon-silver bond [270] (equation 188)... 

Nitric oxide is the simplest thermally stable odd-electron molecule known and, accordingly, its electronic structure and reaction chemistry have been very extensively studied. The compound is an intermediate in the production of nitric acid and is prepared industrially by the catalytic oxidation of ammonia (p. 466). On the laboratory scale it can be synthesized from aqueous solution by the mild reduction of acidified nitrites with iodide or ferrocyanide or by the disproportionation of nitrous acid in the presence of dilute sulfuric acid ... 

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