Catalyst iodine monochloride

Iodine monochloride [7790-99-0] ICl, mol wt 162.38, 78.16% I, is a black crystalline soHd or a reddish brown Hquid. SoHd ICl exists ia two crystalline modifications the a-form, as stable mby-red needles, d = 3.86 g/mL and mp 27.3°C and as metastable brownish red platelets, d = 3.66 g/mL, mp 13.9°C and bp 100°C (dec). Iodine monochloride is used as a halogenation catalyst and as an analytical reagent (Wij s solution) to determine iodine values of fats and oils (see Fats and fatty oils). ICl is prepared by direct reaction of iodine and Hquid chlorine. Aqueous solutions ate obtained by treating a suspension of iodine ia moderately strong hydrochloric acid with chlorine gas or iodic acid (118,119). 

Catalysis by hydrogen chloride or iodine monochloride in chlorination in carbon tetrachloride has also been examined. For the chlorination of pentamethylbenzene, the reaction was first-order in both aromatic and chlorine and either three-halves, or mixed first- and second-order in hydrogen chloride, but iodine monochloride was more effective as a catalyst and the chlorination of mesitylene was first-order in iodine monochloride the activation energy for this latter reaction (determined from data at 1.2 and 25.0 °C) was only 0.4 273. 

Ceric sulphate similarly causes quantitative oxidation. The reaction should take place in the presence of 4N hydrochloric acid, with bivalent manganese present as catalyst and iodine monochloride as indicator. The iodine of the latter is first liberated and then oxidised—8... 

The halogenation of a wide variety of aromatic compounds proceeds readily in the presence of ferric chloride, aluminum chloride, and related Friedel-Crafts catalysts. Halogenating agents generally used are elemental chlorine, bromine, or iodine and interhalogen compounds (such as iodine monochloride, bromine monochloride, etc.). These reactions were reviewed554 and are outside the scope of the present discussion. 

Iodine monochloride has been studied with various fluoroolefins yielding the monoadduct in all cases, to produce original activated telogens containing CF2I or, better, CFC1I end group [114, 115, 156]. The addition of IC1 to 1,1-dichlorodifluoroethylene was found to be bidirectional but to a lesser extent [ 114] than in the case of that to CTFE [115] and the use of catalyst (e. g. iron) affects the yield and the amount of by-product. HFP requires heat contrary to other monomers [114]. 

Iodine monochloride has the advantages of being more efiScient as a catalyst than iodate and of avoiding a blank or uncertainty about final oxidation state that might be encountered in using other iodine compounds. It was shown that relatively large amounts of iodine monochloride could be added without error and that the accuracy was within 1 part in 3000. 

Cerium(IV) standardizations against sodium oxalate are usually performed at 50°C in a hydrochloric acid solution containing iodine monochloride as a catalyst. 

Cerium(IV) solutions can be standardized against primary standard AS2O3, Na2C204, or electrolytic iron. The reaction with arsenic(III) is slow, and it must be catalyzed by adding either osmium tetroxide (OSO4) or iodine monochloride (ICl). Ferroin is used as the indicator. The reaction with oxalate is also slow at room temperature, and the same catalyst can be used. The reaction is rapid, however, at room temperature in the presence of 2 M perchloric acid. Nitroferroin is used as the indicator. 

Catalysts are only infrequently employed in iodination, phosphorus being the principal accelerator. Iodine monochloride, because of its activity under mild operating conditions, is a useful catalyst for the iodination of amino compounds ... 

Electrophilic Addition This can be considered as an acid—base reaction, where the reagent acts as an acid, whether a protic one (e.g., hydriodic acid or iodine monochloride) or a Lewis acid (e.g., molecular iodine, which can be polarized by electrophilic solvents or catalysts), and the double-bond acts as abase (Argentini, 1982). 

A further rapid bimolecular reaction of HOSCN then probably takes place, although further oxidation of this intermediate by I2 cannot be eliminated. In the reaction of iodine monochloride with alcohols, the slow step is the attack of I+ on the alcohol to yield ROI. There is no evidence for any chlorinated product. An n,m.r. study of the exchange between Cl and Cl a in aqueous solution has been reported and comparisons have been made with other halogen exchange processes. The reduction of perchlorate to chloride by molecular hydrogen in the presence of tungsten carbide catalysts has also been described. ... 

Ma.nufa.cture. Sulfur monochloride is made commercially by direct chlorination of sulfur, usually in a heel of sulfur chloride from a previous batch. The chlorination appears to proceed stepwise through higher sulfur chlorides (S Cl2, where x > 2). If conducted too quickly, the chlorination may yield products containing SCI2 and S Cl2 as well as S2CI2. A catalyst, eg, iron, iodine, or a trace of ferric chloride, faciUtates the reaction. The manufacture in the absence of Fe and Fe salts at 32—100°C has also been reported (149—151). 

Industrially, much sulphur monochloride is obtained as a byproduct in the manufacture of carbon tetrachloride by the action of chlorine on carbon disulphide in the presence of a suitable catalyst, e.g. iodine 4... 

Phosphorus trichloride reacts with sulphur monochloride, iodine acting as a catalyst the products are phosphorus pentachloride and phosphorus sulphochloride 8... 

Naphthalene is brominated at room temperature in the absence of a catalyst to a-bromonaphthalene in 75% yield, whereas in the presence of an iron catalyst at 150°-165°C, jJ-bromonaphthalene is formed in 57% yield. Bromine, bromine monochloride [2], iodine monobromide, and A -bromosuccinimide have been employed as brominating agents. 

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