Hydriodic acid, uses

The hydriodic acid used is purified as described on p. 506, selecting for the determination the fraction of constant B.P. 127° and D. T68. The alcoholic silver nitrate, which is prepared by dissolving 4 gms. of silver nitrate in 10 c.cs. of water and adding 90 c.cs. of absolute alcohol, is preserved in a well-stoppered bottle in the dark, and should be filtered and acidified with one drop of nitric acid immediately before use. 

Hydriodic Acid Use special-grade hydriodic acid suitable for alkoxyl determinations, or purify reagent grade as follows Distill over red phosphorus in an all-glass apparatus, passing... 

The cleavage is carried out with hydriodic acid using the procedure for the quantitative determination of N-alkyls (21), and the split off alkyl iodide is converted to the corresponding ester of 3,5-dinitrobenzoic acid in a manner similar to that described for the identification of O-alkyls on p. 202. Chromatographic analysis is also carried out in the same manner. 

Bismuth fluoride (Bip3) is found in the form of white or gray dimorphic crystals, practically insoluble in water, but soluble in concentrated hydrofluoric acid with the formation of complexes. It volatilizes slowly with partial decomposition at high temperatures. Bismuth bromide (BiBr3) is found as yellowish crystals, soluble in aqueous alkali halides and dilute hydrochloric acid, but practically insoluble in alcohols. It is readily decomposed by water to give bismuth oxybromide BiOBr. Bismuth iodide (BiU) is a black fine crystalline solid with a metallic sheen, practically insoluble in water, but slowly decomposes in hot water. It dissolves in liquid ammonia, aqueous potassium iodide, hydriodic acid and hydrochloric acid, but not so much (ca. 3.5%) in absolute ethanol. When exposed to air for a prolonged time, it is slowly converted to bismuth iodate (Bi(I03)3). Bismuth fluoride of 98% purity costs US 24.30 ( 6200) per 25 g, bromide of 98% purity US 24.90 ( 6200), and iodide of 99% US 34.50 ( 8600). These halides are all corrosive and moisture-sensitive. 

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