Iodine tribromide

Other iodine haHdes are iodine monobromide [7789-33-5] IBr, iodine tribromide [7789-58-4] iodHie pentafluoride [7783-66-6] IF, and iodine... 

Chlorine monofluoride, CIF Chlorine trifluoride, CIF3 Bromine monofluoride, BrF Bromine trifluoride, BrF3 Bromine pentafluoride, BrF5 Bromine monochloride, BrCI Iodine trifluoride, IF3 Iodine pentafluoride, IF5 Iodine heptafluoride, IF7 Iodine monobromide, IBr Iodine monochloride, ICI Iodine pentabromide, IBr5 Iodine tribromide, IBr3 Iodine trichloride, ICI3 Iodine pentachloride, ICI5... 

Iodine tribromide, IBrs, is unstable and cannot be isolated as an individual compound. A study of solutions of iodine and bromine in hydrobromic acid by electrometric titrations provided experimental evidence for the existence of IBr3 in the solution [19]. 

Ha.logena.tlon, 3-Chloroindole can be obtained by chlorination with either hypochlorite ion or with sulfuryl chloride. In the former case the reaction proceeds through a 1-chloroindole intermediate (13). 3-Chloroindole [16863-96-0] is quite unstable to acidic aqueous solution, in which it is hydroly2ed to oxindole. 3-Bromoindole [1484-27-1] has been obtained from indole using pytidinium tribromide as the source of electrophilic bromine. Indole reacts with iodine to give 3-iodoindole [26340-47-6]. Both the 3-bromo and 3-iodo compounds are susceptible to hydrolysis in acid but are relatively stable in base. 

The mixture is cooled to room temperature, then filtered. The solvent is removed under reduced pressure, leaving the tribromide (47) as a foam. The foam is mixed with sodium iodide (9.55 g, 0.064 mole) and acetone (74 ml) and heated under reflux in a nitrogen atmosphere for 3.5 hr. The acetone is removed under reduced pressure and the residue is treated with chloroform and aqueous sodium thiosulfate solution. The chloroform layer is separated and washed with sodium thiosulfate solution until it is free from iodine, then dried over magnesium sulfate, filtered and evaporated to dryness under reduced pressure. The crude product (48) is obtained as a brown sohd (4.85 g) which is chromatographed over alumina (122 g, Merck acid-washed). The column is developed with hexane, benzene and ethyl acetate mixtures. The product (3.43 g) is eluted by benzene and benzene-ethyl acetate (10 1). Recrystallization from acetone yields purified 3jS-acetoxy-pregna-5,14,16-trien-20-one (48), 3.25 g, mp 158-159° 309 m/ (e 10,700). 

See Phosphorus tribromide Sulfur acids Phosphorus trichloride Sulfur acids See Other IODINE COMPOUNDS, HALOPHOSPHINES, NON-METAL HALIDES... 

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. 

Undoubtedly, the best method for the production of pure anhydrous lanthanide trihalides involves direct reaction of the elements. However, suitable reaction vessels, of molybdenum, tungsten, or tantalum, have to be employed silica containers result in oxohalides (27). Trichlorides have been produced by reacting metal with chlorine (28), methyl chloride (28), or hydrogen chloride (28-31). Of the tribromides, only that of scandium has been prepared by direct reaction with bromine (32). The triiodides have been prepared by reacting the metal with iodine (27, 29, 31, 33-41) or with ammonium iodide (42). 

The methods discussed produce trihalides of varying purity however, if very pure trihalides are required, they can be sublimed at high temperature from any oxide or oxohalide impurities. The trichlorides can usually be obtained pure, but the tribromides and triiodides tend to be contaminated with oxides and oxoiodides. The various methods of preparing triiodides are compared by a few authors 39, 40, 49, 132), and they recommend their preferred route, which generally is the direct reaction between the metal and iodine. 

Iodine isocyanate, 0524 Nitrogen chloride difhroride, 3978 Nitrogen tribromide hexaammoniate, 0290 Nitrogen trichloride, 4724... 

Lewis acid catalyst is normally required when ammonium polyhalides are used, although recourse does not have to be made to strong acids, such as aluminium trichloride. Bromination and iodination reactions are normally conducted in acetic acid in the presence of zinc chloride [32], but chlorination using the ammonium tetrachloroiodate in acetic acid does not require the additional presence of a Lewis acid [33]. Radical chlorination of toluenes by benzyltrimethylammonium tetrachloroiodate in the presence of AIBN gives mixtures of the mono-and dichloromethylbenzenes [34], Photo-catalysed side-chain chlorination is less successful [35], Radical bromination using the tribromide with AIBN or benzoyl peroxide has also been reported [36, 37],... 

As stated earlier, all other forms of phosphorus can be made from white phosphorus. Thus, heating white phosphorus first at 260°C for a few hours and then at 350°C gives red phosphorus. The conversion is exothermic and can become explosive in the presence of iodine as a catalyst. When a solution of white phosphorus in carbon disulfide or phosphorus tribromide is irradiated the scarlet red variety is obtained. 

Rhenium reacts with all halogens including iodine to yield hahdes in several valence states from -i-1 to -i-6. Such hahdes include dark red hexagonal trichloride, Reds, dark green pentachloride, ReCls, green hexafluoride, ReFe, and the greenish black crystalline tribromide, ReBrs. 

Arsenic Trifluoride, AsF3, is formed when fluorine reacts with arsenic trichloride 1 or with the arsenides of the alkali or alkaline earth metals 2 by the action of anhydrous hydrofluoric acid or of acid fluorides on arsenious oxide 3 by the action of certain metallic fluorides, for example silver or lead fluoride on arsenic trichloride,4 or of ammonium fluoride on arsenic tribromide B and by the action of iodine pentafluoride on arsenic.6... 

Arsenic Pentiodide ( ), Asls.—When a mixture of arsenic and iodine in the requisite proportions is heated in an atmosphere of carbon dioxide in a sealed tube at 150° C., a brown crystalline product is obtained.3 The crystals, which melt at 70° C. and have density 3-93, are soluble in water, carbon disulphide, alcohol, ether and chloroform. The solution in carbon disulphide yields, when allowed to crystallise, a mixture of arsenic triiodide and iodine. The latter is readily lost from the pentiodide, and heating at 100° C. in nitrogen in a sealed tube brings about the decomposition. Like the triiodide, the pentiodide dissolves boron tribromide.4... 

Ketones can be a-brominated on solid phase by treatment with synthetic equivalents of bromine, such as pyridinium tribromide (Entry 2, Table 6.1) or phenyltri-methylammonium tribromide (DCM, 20 °C, 3 h [10]). Resin-bound organometallic compounds, such as vinylstannanes [11] or organozinc derivatives [12], react cleanly with iodine to yield the corresponding vinyl or alkyl iodides (see also Section 3.13). Additions of halogens or their synthetic equivalents to C=C double bonds on cross-... 

The density of the vapour from red or yellow phosphorus is the same, and it corresponds with the mol. P4 hence, from the analogy between a vapour and a solute —1.10, 8—it might be inferred that the two varieties of phosphorus would become identical in a common solvent. If a soln. of yellow phosphorus in phosphorus tribromide—with a trace of iodine as catalytic agent—is kept between 170° and 190°, red phosphorus is gradually deposited. R. Schenck measured the cone, of the yellow phosphorus in soln. after the lapse of different intervals of time, and found the reaction to be bimolecular, but when allowance is made for the mechanical removal of the catalytic agent from the soln. by the precipitated red phosphorus, the reaction is unimolecular. 

Halides are often prepared in a single step from alcohols through use of the Appel reaction. The reagents in this synthesis are tri-phenylphasphine and a halogen species such as tetrachloromethane, hexachloroacetone, or iodine. In place of the Appel reaction it is often possible to use inorganic acid chlorides, including phosphorus tribromide or thionyl chloride (see Chapter 16). 

Iodine isocyanate, 0521 Nitrogen chloride difluoride, 3972 Nitrogen tribromide hexaammoniate, 0289 Nitrogen trichloride, 4137... 

Although the reaction in Scheme 10 is a highly efficient procedure, a two-step process was required to prepare aziridines from olefins. Two more convenient methods for the one-step aziridination using CT were discovered by the authors in 1998, one of which involves the iodine-catalyzed aziridination of unfunctionalyzed olefins with CT trihydrate [7b] (Scheme 11). The bromine-catalyzed aziridination of unfunctionalyzed olefins and allylic alcohols with anhydrous CT was reported at the same time [7c], though in this case phenyltrimethylammonium tribromide (PTAB), and not Br2, was used as a catalyst (Scheme 12). These two reactions are applicable to a wide range of olefins, and are considered to proceed by almost the same pathway. 

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