Iodine distillation

The iodine distils off and can be collected on a cooled surface. It may be purified by sublimation in vacuo. 

This reaction is also used on a large scale, to obtain iodine from seaweed. The ash from burnt seaweed ( kelp ) is extracted with water, concentrated, and the salts other than iodides (sulphates and chlorides) crystallise out. The more soluble iodides remain and the liquor is mixed with sulphuric acid and manganese dioxide added the evolved iodine distils off and is condensed. 

Iodine monochlorlde may be prepared as follows. Pass dry chlorine into 127 g. of iodine contained in a 125 ml. distilling flask until the weight has increased by 34-6 g. The chlorine should be led in at or below the surface of the iodine whilst the flask is gently shaken it is essential to have an excess of iodine. Distil the iodine chloride in an ordinary distillation apparatus use a filter flask, protected from atmospheric moisture by a calcium chloride (or cotton wool) guard tube, as a receiver. Collect the fraction b.p. 97-105° the jdeld is 140 g. Preserve the iodine monochloride in a dry, glass-stoppered bottle. 

It was found impossible to measure the rate of decomposition by the evolution of gases because the release of these gas bubbles is very slow and erratic. The course of the reaction was followed by analyzing samples for the ammonium ion. Small amounts of the decomposing amalgam were forced through a capillary tube into a chilled solution of an iodate. The ammonium reacted with iodate ion to give iodide ion. The solution was then acidified with acetic acid and the iodine distilled out, collected and titrated with sodium thiosulfate. The method was checked with samples... 

The iodine distils over and is collected in a series of glass receivers the other products remain in the retort. 

Reagent-grade methanol is dried by refluxing over magnesium turnings and a little iodine, distilling,... 

Uranium targets have Included the metal and its alloy with aluminum (169) and enriched UOg (3, 169). The irradiated metal was dissolved in nitric acid and the iodine-131 removed with steam or air. The condensate was concentrated and the iodine distilled (yield, about 85%). The irradiated alloy was treated with aqueous sodium hydroxide to bring the aluminum and iodine into solution. The solution was then separated from the uranium, treated with sulfuric acid, and the iodine distilled into a solution of base. The I was purified by... 

Recovery from Elemental Te(169). The tellurium was dissolved in a mixture of chromium(VI) oxide and concentrated sulfuric acid or in one of potassium dichromate and the acid. The periodate formed was reduced to elemental iodine by oxalic acid and the iodine distilled into a solution containing sulfite or thiosulfate. The iodide in solution was oxidized with permanganate and then reduced to the free condition with oxalic acid. The element was again distilled into a reducing solution. Yields up to 90% were obtained. 

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