Preparation of Iodine Trichloride

Using a higher Cl/I ratio, this interhalogen can be prepared in a similar way. 

Add 6 g powdered iodine very slowly to S cm liquid chlorine condensed as above. Allow the temperature to rise slowly when excess chlorine is lost and the yellow orange solid remains. Quickly pack into an ampoule and seal off. 

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To prepare iodine trichloride, heat 20 grms. of iodine in a retort, A, Fig. 26, which delivers into a glass balloon II filled with chlorine, and connected with a Kipp s apparatus C delivering chlorine. The chlorine is rapidly absorbed as soon as it comes in contact with the vapour of iodine, and reddish-yellow crystals of iodine trichloride are formed on the walls of the balloon. The excess of chlorine is finally expelled by a stream of carbon dioxide.. If the crystals are desired, the balloon must bo broken if a soln. of iodine trichloride is desired, the crystals can be dissolved in about ten times their weight of water. 

Preparation of Potassium Tetrachloroiodate Dihydrate. Dissolve 18 g of iodine trichloride in 20 ml of concentrated hydrochloric acid with vigorous stirring in a round-bottomed flask with a ground-glass stopper. Cool the solution to 0 °C and add to it a mixture of 5 g of potassium chloride and 12 ml of a concentrated hydrochloric acid solution. Dilute the reaction mixture to twice its volume with concentrated hydrochloric acid cooled to 0 °C. 

Alicyclic, aromatic, aliphatic, steroidal and triterpenoid 1,2-diols are cleaved by iodine triacetate and iodine(I) acetate to generate carbonyl compounds. Aldehydic products are not further oxidized. Iodine triacetate is prepared from iodine trichloride and silver(I) acetate, whereas iodine(I) acetate is prepared from iotUne and silver(I) acetate. Reactions occur in acetic acid at room temperature under nitrogen, and a radical pathway involving a hypoiodite is suggested. The cost and the availability of these reagents are probable reasons for their unpopularity. 

Diaryliodonium compounds can be prepared by acid-catalyzed condensation of iodoso aryls with another aryl molecule (equation 129). Another method is the use of iodine trichloride in reaction with organometalUc compounds (equations 130 and 131). RICI2 may be prepared by direct chlorination of RI (R = CF3CH2, CHF2(CF2)sCH2) and these materials can be used to chlorinate iodobenzene to give the less hydrolytically stable compound PhICl2. ... 

Chlorovinyliodine(III) dichloride (18), a useful reagents for the synthesis of aryliodonium salts, is prepared by addition of iodine trichloride to acetylene in concentrated hydrochloric acid (Scheme 2.8) [71,88,89], Caution product 18 should be handled with a great care it is extremely unstable and decomposes autocatalytically within seconds. It can, however, be stored for weeks in a freezer at -20 °C or below [71,89]. 

A very mild and selective approach to aryl- and hetaryliodonium chlorides 282 is based on the reaction of aryllithium 280 (generated in situ from bromoarenes and butyllithium) with ( )-chlorovinyliodine(in) dichloride (18) (Scheme 2.82) [71,88,89,403,404]. Tlie iodonium transfer reagent 18 is prepared by the reaction of iodine trichloride with acetylene in concentrated hydrochloric acid (Scheme 2.8 in Section 2.1.3.2) [403] caution this compound is highly unstable and should be handled and stored with proper safety precautions [71]. However, the iodonium transfer procedure with reagent 18 is particularly useful for the preparation of bis(hetaryl)iodonium chlorides 283 from the appropriate nitrogen heterocycles 282 (Scheme 2.82) [71]. 

The iodine monochloride reagent is best prepared by dissolving 8 g of iodine trichloride in about 200 ml of glacial acetic acid and 9 g of iodine in 300 ml of carbon tetrachloride before mixing the two solutions and diluting to 1 litre with glacial acetic acid. It should be stored in a cool place in a stoppered bottle protected from light. 

Iodine trichloride [865-44-17, ICl, mol wt 233.39, 54.40% I, is a yellow or brownish powder. It is pungent and has a very irritating odor. It decomposes at 77°C iato ICl and CI2. It is prepared by adding finely powdered iodine to an excess of Hquid chlorine. It is used as a chlorinating and oxidising agent (120). 

Both yellow and red phosphorus ignite on contact with fluorine and chlorine red ignites in liquid bromine or in a heptane solution of chlorine at 0°C. Yellow phosphorus explodes in liquid bromine or chlorine, and ignites in contact with bromine vapour or solid iodine [1]. Interaction of bromine and white phosphorus in carbon disulfide gives a slimy by-product which explodes violently on heating [2], Interaction of phosphorus and iodine in carbon disulfide is rather rapid [3], A less hazardous preparation of diphosphorus tetraiodide from phosphorus trichloride and potassium iodide in ether is recommended [4],... 

First, the methods that apply to all three trihalides are reviewed then other specific methods are mentioned. Far fewer methods have been perfected for preparing anhydrous lanthanide tribromides than for the trichlorides, though most of them are similar. The triiodides are the most difficult to prepare, as the iodine analogs of several useful chloro and bromo sulfur and carbon compounds are not known. Reaction temperatures for preparation of triiodides have to be carefully controlled, as Sml3 and Ybl3, for example, decompose easily at elevated temperatures to diiodides. The existence of Eul3 is questionable, with EuI2 formed even at room temperature. 

Arsenic triiodide is prepared by treating elemental arsenic with a solution of iodine in carbon disulfide. Alternatively, it can be precipitated out from a hot solution of arsenic trioxide or arsenic trisulfide in hydrochloric acid on treatment with potassium or sodium iodide. Also, it is made by the reaction of arsenic trichloride with potassium iodide. 

Vanadium metal is prepared from pentoxide, V2O5, by reduction with calcium at elevated temperatures. Presence of iodine lowers calcium reduction temperature to 425°C because of heat of formation of calcium iodide. Pentoxide also may be converted to the trichloride, VCI3, and the trichloride reduced with magnesium metal or magnesium-sodium mixture at high temperatures to form high purity ductile metal. Alternatively, a fused mixture of vanadium chloride, sodium chloride, and hthium chloride may be electrolyzed to produce the metal in high purity. 

Chlorine and iodine.—In the course of his historic research on iodine, J. L. Gay Lussac (1814) 6 prepared a compound of iodine and chlorine by the action of chlorine gas on iodine—the gas was absorbed by the solid forming a reddish-brown liquid which is so remarkably like bromine, that before that element had been recognized as a distinct chemical individual by A. J. Balard, J. von Liebig mistook bromine for iodine chloride. If the chlorine be in excess, citron-yellow needle-like crystals are formed. The liquid product is iodine monochloride the crystalline solid is iodine trichloride. H. Davy called the product formed by the action of iodine on chlorine, olilorionio acid, and he regarded it as a compound consisting of one proportion of iodine and one of chlorine —i.e. iodine monochloride. 

Iodine trichloride.—This compound was discovered by J. L. Gay Lussac as the result of treating warm iodine or iodine monochloride with an excess of chlorine. The trichloride collects as a citron-yellow crystalline sublimate on the cooler parts of the vessel. It is also formed by the action of liquid chlorine on iodine, or an iodide—say lead iodide.18 The iodine trichloride is almost insoluble in liquid chlorine, and hence, say Y. Thomas and P. Dupuis, this method of preparation is very convenient. It is also formed by the action of dry chlorine on hydrogen iodide (A. Christomanos) silver iodate (J. Krutwig) or methyl iodide (L. von... 

F. C. Mathers and C. G. Schluderberg 124 prepared indium iodate, In(I03)3, by mixing soln. of indium trichloride and potassium iodate. The precipitate is amorphous. The mixture was evaporated to dryness on a water-bath the residue extracted on a Gooch s crucible with warm water and dried in vacuo over sulphuric acid. The mass was dissolved in boiling nitric acid (1 10), and on evaporation white crystals of indium iodate were formed. 100 grms. of water at 20° dissolve 0 067 grm., and 100 grms. of nitric acid (1 5) at 80° dissolve 0 67 grm. of the salt. It also dissolves in dil. sulphuric or hydrochloric acid. The soln. in the last-named add decomposes with the liberation of chlorine. The crystals decompose with the evolution of iodine when heated by a free flame and explode if touched with a red-hot iron wire. 

Transfer the iodine trichloride from the flask into a weighed drawn out test tube. Cool the tube with dry ice and rapidly seal it wear eye protection ). Weigh the test tube with the substance and the remaining fragments of the tube. Calculate the yield in per cent. Write the equation of the reaction. Use the prepared iodine trichloride in the following syntheses. 

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