Bromide aluminum

Heating over 1100°C with N2 produces nitride, AIN alkoxides are formed when the metal powder is treated with anhydrous alcohol, catalyzed hy HgCb 

Reaction with CO at 1000°C produces the oxide AI2O3 and the carbide AI4C3. 

The metal may he analyzed hy atomic absorption or emission spectrophotometry (at trace levels). Other techniques include X-ray diffraction, neutron activation analysis, and various colorimetric methods. Aluminum digested with nitric acid reacts with pyrocatechol violet or Eriochrome cyanide R dye to form a colored complex, the absorbance of which may be measured by a spectrophotometer at 535 nm. 

Finely divided aluminum dust is moderately flammable and explodes by heat or contact with strong oxidizing chemicals. Chronic inhalation of the powder can cause aluminosis, a type of pulmonary fibrosis. It is almost nontoxic by ingestion. 

The anhydrous form is used as a catalyst for the Friedel-Crafts alkylation reaction. Its catalytic activity is similar to anhydrous AICI3. Commercial applications, however, are few. 

Submitted by Douglas G. Nicholson, Paul K. WiNTEB,t and Hebt BERT FiNEBERO  

Aluminum bromide has been finding increasing application as an acid catalyst in organic synthesis it has recently become of industrial importance in the alkylation of aromatic hydrocarbons with ethylene, and in the isomerization of normal hydrocarbons. It is also used in the polymerization of olefins, and to some extent in the Friedel-Crafts reaction. It has been found particularly useful in such reactions since it is not only more soluble in organic media, but also more active catalytically than aluminum chloride. Winter and Cramer have described a procedure for pre- 

A diagram of the apparatus used for the preparation of aluminum bromide in larger amounts is shown in Fig. 9. The reaction vessel A consists of a 250-ml. distilling flask 

Apparatus for the preparation of aluminum bromide in larger quantities. 

Sixty grams of bromine, dried over concentrated sulfuric acid, is placed in B. The bottom area of the reaction flask A is covered with a thin layer of dry glass wool. SuflBcient granular aluminum (30-mesh), dried in an oven at 110° for several hours, is placed in the reaction flask to fill the latter almost to the mouth of the exit tube leading to the receiver D. The dry reaction flask containing the granular alumi- 

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Ben2enesulfonic anhydride has been claimed to be superior to ben2enesulfonyl chloride (140). Catalysts used besides aluminum chloride are ferric chloride, antimony pentachloride, aluminum bromide, and boron trifluoride (141). 

Aluminum bromide and chloride are equally active catalysts, whereas boron trifluoride is considerably less active probably because of its limited solubiUty in aromatic hydrocarbons. The perchloryl aromatics are interesting compounds but must be handled with care because of their explosive nature and sensitivity to mechanical shock and local overheating. 

Anhydrous aluminum bromide, AIBr., forms colorless trigonal crystals and exists in dimeric form, in the crystal and Hquid phases (1). Dissociation... 

Aluminum bromide hexahydrate [7784-11-4] AIBr. 6H20, may be made by dissolving aluminum or aluminum hydroxide ia hydrobromic acid [10035-10-6] HBr. This white, crystalline soHd is precipitated from aqueous solution. 

Zirconium tetrabromide [13777-25-8] ZrBr, is prepared direcdy from the elements or by the reaction of bromine on a mixture of zirconium oxide and carbon. It may also be made by halogen exchange between the tetrachloride and aluminum bromide. The physical properties are given in Table 7. The chemical behavior is similar to that of the tetrachloride. 

Bromine can function as a solvent. One of the very few metal bromides that has significant solubiUty in bromine is cesium bromide, 19.3 g/100 g of solution, thus providing a method of separating cesium bromide from the other alkah bromides (12). Aluminum bromide also is reported to have significant solubiUty in bromine but the pubUshed solubiUty values are not in good agreement (13). Bromine serves as the solvent in some brominations of organic compounds, such as 1,2-diphenylethane (14). 

Boron tribromide [10294-33A], BBr, is used in the manufacture of diborane and in the production of ultra high purity boron (see Boron, ELEMENTAL BoRON COMPOUNDS). Anhydrous aluminum bromide [7727-15-3], AIBr., is used as an acid catalyst in organic syntheses where it is more reactive and more soluble in organic solvents than AlCl. Tballium bromide [7789AOA], TlBr, is claimed as a component in radiographic image conversion panels (39). 

At 225—275°C, bromination of the vapor yields bromochloromethanes CCl Br, CCl2Br2, and CClBr. Chloroform reacts with aluminum bromide to form bromoform, CHBr. Chloroform cannot be direcdy fluorinated with elementary flourine fluoroform, CHF, is produced from chloroform by reaction with hydrogen fluoride in the presence of a metallic fluoride catalyst (8). It is also a coproduct of monochlorodifluoromethane from the HF—CHCl reaction over antimony chlorofluoride. Iodine gives a characteristic purple solution in chloroform but does not react even at the boiling point. Iodoform, CHI, may be produced from chloroform by reaction with ethyl iodide in the presence of aluminum chloride however, this is not the route normally used for its preparation. 

When treated with aluminum bromide at 100°C, carbon tetrachloride is converted to carbon tetrabromide [558-13-4], reaction with calcium iodide, Cal2, at 75°C gives carbon tetraiodide [507-25-5]. With concentrated hydroiodic acid at 130°C, iodoform [75-47-8], CHI, is produced. Carbon tetrachloride is unaffected by gaseous fluorine at ordinary temperatures. Replacement of its chlorine by fluorine is brought about by reaction with hydrogen fluoride at a... 

Photochlorination of tetrachloroethylene, observed by Faraday, yields hexachloroethane [67-72-1]. Reaction with aluminum bromide at 100°C forms a mixture of bromotrichloroethane and dibromodichloroethane [75-81-0] (6). Reaction with bromine results in an equiUbrium mixture of tetrabromoethylene [79-28-7] and tetrachloroethylene. Tetrachloroethylene reacts with a mixture of hydrogen fluoride and chlorine at 225—400°C in the presence of zirconium fluoride catalyst to yield l,2,2-trichloro-l,l,2-trifluoroethane [76-13-1] (CFG 113) (7). 

AIBt3, EtSH, 0°, 0.5-1 h, 73-78% yield. Aluminum bromide cleaves aryl and alkyl methyl ethers in high yield methyl esters are stable. 

There are relatively few kinetic data on the Friedel-Crafts reaction. Alkylation of benzene or toluene with methyl bromide or ethyl bromide with gallium bromide as catalyst is first-order in each reactant and in catalyst. With aluminum bromide as catalyst, the rate of reaction changes with time, apparently because of heterogeneity of the reaction mixture. The initial rate data fit the kinetic expression ... 

Hydrogen Bromide (15,35) In 80-90 per cent yields by the addition of bromine dropwise to petroleum in the presence of aluminum bromide. Ionescu and Radulescu, Bull. soc. chim. Romania 17, 309 (1935) [C. A. 30, 6300 (1936)]. 

Rate law and mechanism. The redistribution of alkyl groups on silanes in benzene is catalyzed by aluminum bromide. Suggest a scheme for it on the basis of the rate equation given. 

As shown in Table IV, the highest catalytic activity of metal halides used as Lewis acid for the alkylation reaction of ferrocene with 2 was observed in methylene chloride solvent. Among Lewis acids such as aluminum chloride, aluminum bromide, and Group 4 transition metal chlorides (TiCl4, ZrCU, HfCU), catalytic efficiency for the alkylation decrea.ses in the following order hafnium chloride > zirconium chloride > aluminum chloride > aluminum bromide. Titanium chloride... 

In the solid state, aluminum chloride exists in a crystalline lattice. Each aluminum atom is surrounded by six chlorine atoms arranged around the metal atoms at the comers of an octahedron. Aluminum bromide and aluminum iodide form AI2 Xj molecules in all three phases. 

Treatment of compound 6-1 in dibromethane with one equivalent of aluminum bromide yields 6-2 as the only product in 78% yield. When three equivalents of... 

If a solution instead of suspension is used, troublesome gel formation may occur during the aluminum bromide addition. 

Colorless, crystalline, anhydrous aluminum bromide supplied by the Westvaco Chemical Division, Food Machinery and Chemical Corporation, New York, New York, was used. When dissolved in dry benzene at room temperature with mechanical stirring, a perfectly clear yellow solution results, if the reagents are of high purity. 

Ans. (a) Sodium bromide, NaBr (t>) magnesium bromide, MgBr2 and (c) aluminum bromide, AIBr,. The bromide ion has a 1— charge. The sodium, magnesium, and aluminum ions have charges of 1 +, 2+, and 3+, respectively, and the subscripts given are the smallest possible to just balance the charges. 

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