Iron III bromide

Iron(III) chloride forms numerous addition compounds, especially with organic molecules which contain donor atoms, for example ethers, alcohols, aldehydes, ketones and amines. Anhydrous iron(III) chloride is soluble in, for example, ether, and can be extracted into this solvent from water the extraction is more effective in presence of chloride ion. Of other iron(III) halides, iron(III) bromide and iron(III) iodide decompose rather readily into the +2 halide and halogen. 

The classification of hydrocarbons as aliphatic or aromatic took place m the 1860s when It was already apparent that there was something special about benzene toluene and their derivatives Their molecular formulas (benzene is CgHg toluene is C7Hj ) indicate that like alkenes and alkynes they are unsaturated and should undergo addition reac tions Under conditions m which bromine for example reacts rapidly with alkenes and alkynes however benzene proved to be inert Benzene does react with Bi2 m the pres ence of iron(III) bromide as a catalyst but even then addition isn t observed Substitu tion occurs instead ... 

The active catalyst is not iron itself but iron(III) bromide formed by reaction of iron and bromine... 

Iron(III) bromide is a weak Lewis acid It combines with bromine to form a Lewis acid Lewis base complex... 

Complexation of bromine with iron(III) bromide makes bromine more elec trophilic and it attacks benzene to give a cyclohexadienyl intermediate as shown m step 1 of the mechanism (Figure 12 6) In step 2 as m nitration and sulfonation loss of a proton from the cyclohexadienyl cation is rapid and gives the product of electrophilic aromatic substitution... 

Only small quantities of iron(III) bromide are required It is a catalyst for the brommation and as Figure 12 6 indicates is regenerated m the course of the reaction We 11 see later m this chapter that some aromatic substrates are much more reactive than benzene and react rapidly with bromine even m the absence of a catalyst... 

Step 1 The bromine-iron(III) bromide complex is the active electrophile that attacks benzene... 

Iron(III) bromide [10031-26-2], FeBr, is obtained by reaction of iron or inon(II) bromide with bromine at 170—200°C. The material is purified by sublimation ia a bromine atmosphere. The stmcture of inoa(III) bromide is analogous to that of inon(III) chloride. FeBr is less stable thermally than FeCl, as would be expected from the observation that Br is a stronger reductant than CF. Dissociation to inon(II) bromide and bromine is complete at ca 200°C. The hygroscopic, dark red, rhombic crystals of inon(III) bromide are readily soluble ia water, alcohol, ether, and acetic acid and are slightly soluble ia Hquid ammonia. Several hydrated species and a large number of adducts are known. Solutions of inon(III) bromide decompose to inon(II) bromide and bromine on boiling. Iron(III) bromide is used as a catalyst for the bromination of aromatic compounds. 

Feiri-. ferric, ferri-, iron(III). -acetat, n. ferric acetate, iron(IIl) acetate, -ammonsulfat, n. ammonium ferric sulfate, -bromid, n. ferric bromide, iron(III) bromide, -chlorid, n. ferric chloride, iron(lll) chloride, -chlor-wasserstoff, -chlorwasserstoffsMure, /. fer-richloric acid. -cyan, n. ferricyanogen. -cyaneisen, n. ferrous ferricyanide (Turn-bull s blue), -cyanid, n. ferric cyanide, iron(III) cyanide ferricyanide. 

Arenes are unsaturated but, unlike the alkenes, they are not very reactive. Whereas alkenes commonly take part in addition reactions, arenes undergo predominantly substitution reactions, with the TT-bonds of the ring left intact. For example, bromine immediately adds to a double bond of an alkene but reacts with benzene only in the presence of a catalyst—typically, iron(III) bromide—and it does not affect the bonding in the ring. Instead, one of the bromine atoms replaces a hydrogen atom to give bromobenzene, C H Br ... 

The bromination of benzene illustrates the difference between addition to alkenes and substitution of arenes. First, to achieve the bromination of benzene it is necessary to use a catalyst, such as iron(III) bromide. The catalyst acts as a Lewis acid, binding to the bromine molecule (a Lewis base) and ensuring that the outer bromine atom has a pronounced partial positive charge ... 

Scheme 9 Iron(III) bromide-mediated cyclization of aryl glycidyl ethers to 3-chromanols...

Ans. (a) Iron(II) bromide and iron(III) bromide, FcBr, and FeBr, (b) palladium ID bromide and palladium(IV) bromide, PdBr, and PdBr4 and (c) mercuryd) bromide and mereury(II) bromide. Hg.Br, and HgBr,. (The charges on the cations can be obtained from Table 6-4.)... 

NaBr sodium bromide FeBr3 iron(III) bromide or ferric bromide... 

Iron blacks, 79 401-402 Iron blast furnace, 76 141-143 Iron Blue, pigment for plastics, 7 370t Iron blue pigments, 79 407 Iron(II) bromide, 74 539 Iron(III) bromide, 74 539-540 Iron brown hematite, formula and DCMA number, 7 347t Iron browns, 79 402 Iron carbide, 4 649t, 690—692 lattice, 4 652... 

Dibromogermane, 0267 Germanium tetrachloride, 4162 Gold(III) chloride, 0111 Indium bromide, 0289 Iridium hexafluoride, 4362 Iron(II) bromide, 0266 Iron(III) bromide, 0286 Iron(II) chloride, 4061 Iron(III) chloride, 4133 Iron(II) iodide, 4395... 

As you learned in Chapter 1, aromatic compounds do not react in the same way that compounds with double or triple bonds do. Benzene s stable ring does not usually accept the addition of other atoms. Instead, aromatic compounds undergo substitution reactions. A hydrogen atom or a functional group that is attached to the benzene ring may be replaced by a different functional group. Figure 2.6 shows two possible reactions for benzene. Notice that iron(III) bromide, FeBrs, is used as a catalyst in the substitution reaction. An addition reaction does not occur because the product of this reaction would be less stable than benzene. 

Iron(III) bromide is a catalyst in bromination of aromatic compounds. 

Iron (III) bromide is prepared by the action of bromine with iron filings 2Fe -I- 3Br2 —> 2FeBrs... 

Iron(III) bromide forms several adduct witb donor molecules in solutions. For... 

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