Acid Iodine Pentoxide

Explain the secondary reaction of the foregoing preparation in which chlorine reacts with iodine. 

From knowledge of the reactions of chlorine and bromine predict how iodine would react with a KOH solution. Find from reference books whether this prediction is borne out by the facts. 

Iodine pentoxide is a white solid substance that, at ordinary temperatures, is entirely stable. It cannot be prepared by direct synthesis from iodine and oxygen, because when cold the elements combine too slowly, and when heated the compound is unstable. It may be readily prepared by the direct oxidation of iodine by means of strong oxidizing agents, such as concentrated nitric acid or chlorine. One method for the oxidation of iodine has already been illustrated under the preparation of potassium iodate, but 

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The iodic acid may then be dehydrated by heat, giving iodine pentoxide... 

Under high pressures and temperatures, iodine reacts with oxygen to form iodine pentoxide [12029-98-0] (44). The reaction of iodine with carbon monoxide under acidic conditions is catalyzed by palladium salts (45). Phosphorous vapor and iodine react to form phosphoms trHodide [13455-01 -17, PI (46). 

Iodine dissolves without reaction in concentrated sulfuric acid and with concentrated nitric acid it reacts to form iodine pentoxide (47). Iodine reacts with alkah metal hydroxide solutions to form the corresponding hypoiodite and the rate of the reaction increases with the alkaU concentration and temperature. At 50°C, the reaction is almost instantaneous ... 

Chlorine heptoxide is more stable than either chlorine monoxide or chlorine dioxide however, the CX C) detonates when heated or subjected to shock. It melts at —91.5°C, bods at 80°C, has a molecular weight of 182.914, a heat of vapori2ation of 34.7 kj/mol (8.29 kcal/mol), and, at 0°C, a vapor pressure of 3.2 kPa (23.7 mm Hg) and a density of 1.86 g/mL (14,15). The infrared spectmm is consistent with the stmcture O CIOCIO (16). Cl O decomposes to chlorine and oxygen at low (0.2—10.7 kPa (1.5—80 mm Hg)) pressures and in a temperature range of 100—120°C (17). It is soluble in ben2ene, slowly attacking the solvent with water to form perchloric acid it also reacts with iodine to form iodine pentoxide and explodes on contact with a flame or by percussion. Reaction with olefins yields the impact-sensitive alkyl perchlorates (18). 

Phenyl isothiocyanate has been prepared from thiocarbanilide by the action of phosphorus pentoxide, hydrochloric acid, iodine, phosphoric acid, acetic anhydride, and nitrous acid. It has also been prepared from ammonium phenyl dithiocarbamate by the action of ethyl chlorocarbonate, copper sulfate lead carbonate, lead nitrate, ferrous sulfate,and zinc sulfate. ... 

Iodine pentoxide is prepared by dehydration of iodic acid at 240°C. 

Ilosvay) by the action of hydrogen chloride on iodic acid (G. S. Serullas) of phosphorus pentachloride on iodine pentoxide (0. Brenkn) of iodine on sulphuryl chloride in excess (0. Ruff) 3S02Cl2+l2=2ICl3+3S02 and by heating iodine monochloride. 

The material is best heated in a tube between 90° and 110° so that the first portion of the water may be expelled without fusion. The temp, is then raised to 220°, and the operation concluded by a 4 hrs. heating at 240°, dry and purified air is passed through the tube during the operation. If fusion occurs before dehydration, some iodic acid may be enclosed within an impervious coating of anhydrous salt, and the escape of water prevented. If the air is inadequately dried, the iodine pentoxide may become brown, probably owing to the liberation of iodine and a similar result is obtained when the temp, rises over 250°. 

According to A. Ditte,7 the iodine pentoxide which has separated from an acid soln. slowly loses some water at 180°, and rapidly if the powdered substance is heated to 200°-210°, and even after heating to 250°, it may contain up to 0 006 per cent. 

According to H. W. Foote and L. H. Levy, soln. of the alkali chlorates in other molten salts gave f.p. indicating that the mol. wt. under those conditions are normal. A. Rosenheim and 0. Liebknecht48 found the mol. wt. of acid by the f.p. method depend on the concentration, and that the acid in dil. soln. is a monobasic acid, and in cone. soln. the acid is polymerized and exists as a dibasic acid, H2l206. E. Gro-schuff and P. Walden also showed that the electrical conductivity of iodic acid soln. corresponds with a monobasic acid, as is also the case with chloric and bromic acids. The monobasic acid, therefore, can be represented by A. Kekule s type of formula with iodine univalent or C. W. Blomstrand s type of formula, with iodine quinquevalent and iodic anhydride, i.e. iodine pentoxide will be represented ... 

E. Muller made potassium iodate by electrolyzing the iodide. H. L. Wheeler 44 made rubidium iodate, RbI03, by the action of a mol. of iodine pentoxide on one of rubidium carbonate by treating a hot dil. soln. of iodine trichloride with rubidium hydroxide or carbonate by the action of iodic acid on a hot cone. soln. of rubidium chloride, RbCl. T. V. Barker obtained a good yield by passing chlorine into a hot cone. soln. of a mixture of rubidium iodide and hydroxide whereby the sparingly soluble iodate is precipitated. Caesium iodate, CsI03, was made in a similar way. 

Chlorine heptoxide is more stable than either chlorine monoxide or chlorine dioxide however, the CI2O7 detonates when heated or subjected to shock. It melts at —9l.5°C, boils at 80 0, has a molecular weight of 182 914. Tt is soluble in benzene, slowly attacking the solvent with water to form perchloric acid it also reacts with iodine to form iodine pentoxide and explodes on contact with a flame or by percussion, Reaction with olefins yields the impact-sensitive alkyl perchlorates. 

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