Iodination s. a. Halogenation

Replacement) 31, 510 lodinanes s. Iminoiodinanes lodination (s. a. Halogenation, Replacement of hydrogen by halogen) electrochemical 31, 482 Iodine 4, 685s3l 16, 780s31 ... 

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). 

Attempts to oxidise silver dithiocarbamato complexes with halogens to compounds with the metal in higher oxidation states obviously failed. By addition of iodine to a solution of [Ag(Bu2 fc)]g in CHQ3, an insoluble product is formed with the composition rjA% S> X2dtc) 141). With other alkyl groups similar complexes are obtained. Investigations about the nature of this type of compounds are in progress. 

See other a-halogen compounds, n-s compounds, iodine compounds... 

See other A -HALOGEN COMPOUNDS, IODINE COMPOUNDS, N—S COMPOUNDS... 

A great deal of evidence has been obtained in support oT the mecha nism shown in Figure 22.4. For example, the rate of halogenation is indc< pendent of the halc [eit s identity Chlorination, bromination, and iodination of a given aldehyde or ketone all occur at the same rate, indicating that the same ratediniiting step is involved and that the halogen has no past in that step. 

Several trends are noticeable from the data in the table. The bond strengths of the interhalogens are clearly related to the dift erence in electronegativity between tbe component halogen atoms, as expected on the basis of Pauling s ideas on ionic character (Chapter 5). Furthermore, the tendency to form the higher fluorides and chlorides depends upon the initial eiectronegativiiy of the central atom.- Only iodine forms a heptafluoride or a trichloride. Not shown in Table 17.2 (except indirectly by computation from the values) is the instability of certain lower oxidation states to disproportionation ... 

I. Gilman s catalyst is prepared readily by heating an alloy of magnesium containing 12.75 per cent of copper with about 20 per cent by weight of iodine in an evacuated flask. Only about 0.25 g. of this catalyst is required to bring about a reaction with a halogen compound. When this catalyst is used, the... 

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