Hydrogen iodide melting point

Bromine attacks it at red heat with incandescence chlorine is less vigorous in its action, whilst iodine and hydrogen iodide have no action, even at 1100° C. The chlorate and nitrate of potassium do not affect it at their melting-points, but at higher temperatures decompose it with incandescence. Fused alkali hydroxides and carbonates decompose it rapidly. Concentrated sulphuric acid is without action in the cold, but with the boiling acid ferrous sulphate is produced. Dilute nitric acid dissolves it when hot, and the concentrated acid acts vigorously. Dilute hydrochloric acid is without action, and the hot concentrated acid acts only slowly. 

The filtrate was adjusted to a pH of 9 by adding concentrated ammonia, and then a 1 N aqueous iodine-potassium iodide solution was added dropwise, whereby the tetrahydro-pyrimido-[5,4-d] pyrimidine obtained by hydrogenation with zinc in formic acid was converted by oxidation into 2,6-bis-(diethanolamino)-8-piperidino-pyrimldo-[5/4-dl-pyrimidine. The completion of the oxidation was checked by means of a starch solution. The major amount of the oxidation product already separated out as a deep yellow crystalline precipitate during the addition of the iodine solution. After the oxidation reaction was complete, the reaction mixture was allowed to stand for a short period of time, and then the precipitate was separated by vacuum filtration, washed with water and dried. It had a melting point of 157°C to 158°C. The yield was 8.0 g, which corresponds to 95% theory. 

Table 4.14 shows the increase in melting and boiling points of the hydrogen halides from hydrogen chloride to hydrogen iodide. All the molecules have a linear shape. 

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