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Aluminum tribromide,

Other Rea.ctions, The photolysis of ketenes results in carbenes. The polymeriza tion of ketenes has been reviewed (49). It can lead to polyesters and polyketones (50). The polymerization of higher ketenes results in polyacetals depending on catalysts and conditions. Catalysts such as sodium alkoxides (polyesters), aluminum tribromide (polyketones), and tertiary amines (polyacetals) are used. Polymers from R2C—C—O may be represented as foUows. [Pg.475]

Complex Formation. B-Ttichlorobora2iQe was reported to readily form crystalline adducts of uncertain stmcture with pyridine (131). The Lewis acids aluminum tribromide or gallium trichloride form 1 1 adducts with hexamethylbota2iQe (eq. 36) ia which the metal atom coordinates with a nitrogen with loss of planarity of the ring (132,133). [Pg.266]

Many reactions of fluorinated organics with metal halides result in the replacement of fluorine with halogen A general route to 1,1,1-trichloro- or tribromo-fluoroalkanes involves treating primary fluoroalkyl iodides with aluminum trichloride or aluminum tribromide [74], Benzylic [75, 76] or vinylic [72] fluorine can be exchanged for chlorine when treated with aluminum trichloride... [Pg.381]

The formal addition of a methane molecule to a ft-pyrrolic C — C double bond can be achieved when bishydroxytin(IV) octaethylporphyrin 17 is first treated with a chloroform/aluminum tribromide mixture to give 18 which can subsequently be reduced with sodium borohydride and dcmctalated with acid to give the methylated chlorin 19.23... [Pg.622]

We found highly active catalysts, which are shown in Table I (3). The main component is a stable carboxylate of uranium in the oxidation state of +4, in combination with a Lewis acid and an aluminum alkyl, e.g. uranium octoate, aluminum tribromide, and triisobutylaluminum in a molar ratio of 1 0.8 25. The catalyst is usually aged for at least 2 hours at room temperature. [Pg.58]

Anhydrous metal halides Aluminum tribromide, germanium tetrachloride, titanium tetrachloride... [Pg.60]

Aluminum tribromide, adducts with carbonyl clusters, 24 258 Aluminum trichloride... [Pg.8]

Aluminum trichloride is the most commonly used catalyst, although aluminum tribromide is more efficient.1 For the rearrangement of l-broino-2-chloro-1,L2-lrifluoroethane (3) to 2-bromo-2-chloro-l,l,l-trifhioroethane (4). none of the following Lewis acids are effective iron(III) chloride. iron(III) bromide, antimony(III) chloride, antimony(V) chloride. tin(IV) chloride, titanium(IV) chloride, zinc(II) chloride, and boron trifluoride-diethyl ether complex.1" ... [Pg.164]

Much work has been done to develop catalyst systems that optimize yield and reduce side reactions. The reaction has an induction period, which depends on the temperature and the amount of catalyst.8 An early patent from Bayer claims that a nearly quantitative yield can be achieved in the conversion of l,2-dibromo-1-chloro-l.2.2-trifluoroethane(5) into 1,1-di-bromo-l-chloro-2,2.2-trifluoroethane (6) when aluminum tribromide is used in 2-broino-2-chloro-1,1,1-trifluoroethane (4) as solvent.12 A Japanese patent26 describes the activation of aluminum trichloride or alumina by pretreatinent with l,L2-trichloro-l,2,2-trifluoroethane (1) (see discussion of compound 19, vide infra). A later patent claims that aluminum trichloride and tribromide can also be activated by complexing with 1,1-dichloro- (CF3CFC12) and 1,1-dibromo-1,2,2,2-tetrafluoroethane (CF3CFBr2), respectively 2 an example of the latter is shown in the formation of bromofluoroalkane 10. [Pg.164]

The electrophilic rearrangement of 2,3-dibromotetrafluoropropene (5) has been achieved with aluminum tribromide in high yield under mild conditions 9- the dibromide 6 is an intermediate in the synthesis of tetraflnoropropyne. [Pg.169]

Most of the investigations into disproportionation reactions have mainly concentrated on chlorofiuoro derivatives of methane and ethane. When trichlorofluoromethane is refluxed with aluminum trichloride or aluminum tribromide, dichlorodifluoromethane and carbon tetrachloride are obtained. Dichlorofluoromethane yields chlorodifiuoromethane and chloroform chlorofiuoro derivatives of ethane and longer chain homologs exhibit a tendency towards isomerization as well as disproportionation, i.e. intramolecular halogen atom exchange. In this case, both types of reaction take place simultaneously. In other words, disproportionation of l,l,2-triehloro-1.2,2-trifiuoroethane (1) forms l,l,1.2-tetrachloro-2,2-difluoroethane (2) and... [Pg.281]

The catalysts used successfully in the liquid phase in the order of their efficiency are anti-niony(V) chloride, aluminum tribromide, aluminum trichloride, and iron(Ill) chloride. Zinc(ll) chloride, tin(ll) chloride, boron trifluoride diethyl ether complex, and aluminum trifluoridc do not catalyze the dismutation. [Pg.289]

Transbromination of ketones and activated aromatic compounds (phenols, naphthols, indole) by 4-(tribromomethyl)quinazoline is catalyzed by TFA245. Alkanes are brominat-ed by complexes of bromoform with aluminum tribromide (equation 33)246. [Pg.552]

In sharp contrast, benzene is unreactive with bromine tinder these same conditions. Under more vigorous reaction conditions (the presence of a Lewis acid catalyst, such as aluminum tribromide, and higher temperature), benzene does react with bromine However, the product results from a substitution of a Br for a H, rather than addition of Br2 to one of the double bonds. The product retains the benzene structure of three conjugated double bonds in a six-membered ring ... [Pg.643]

These systems are not catalytic in the true sense because solvolysis, with resultant destruction of the active species, is needed to liberate NH3. However, by controlled solvolysis followed by removal of the NH3, a further cycle of reduction, N2 absorption, and solvolysis often can be made. Titanium retains activity through about five such cycles in the tetra-isopropoxytitanium-sodium-naphthalenide system in ether using propan-2-ol for solvolysis (10). By using a nonprotic Lewis acid, aluminum tribromide, the catalytic effect of Ti is demonstrated. When N2 (100 atm pressure) is treated with a mixture of titanium tetrachloride, metallic aluminum, and aluminum tribromide at 130°C as much as 284 mol of NH3 per mol of TiCl4 is obtained after hydrolysis. This, then, is a system for the catalytic nitriding of Al (13). A similar system operating electrochemically yields 6.1 mol NH3 per g atom Ti in 11 days (14). [Pg.353]

Dimethyl tellurium dibromide and boron tribromide formed a thermally unstable 2 1 adduct4. Calorimetric titrations indicated that 1 1 complexes are formed between diphenyl tellurium dihalides and aluminum tribromide or gallium trichloride5 6. [Pg.568]

SYNS ALL iMINUM BROiMIDE, anhydrous (UN 1725) pOT) ALUMINUM BROMIDE, solution (UN 2580) pOT) ALUMINUM TRIBROMIDE TRIBROMOALUMINUM... [Pg.45]

Chromic acid oxidation of 1- or 2-methylphenazine affords the corresponding carboxylic acids and oxidation with selenium dioxide gives the corresponding aldehydes.Alkoxyphenazi-nes are readily dealkylated using hydrobromic acid in acetic acid, or with aluminum tri-halides. Alkoxyphenazine A -oxides can be also dealkylated with aluminum trichloride in ethereal solution or aluminum tribromide in benzene. " ... [Pg.294]

In the 1 1 adducts of phenyl tellurium trichloride or tribromide with aluminum tribromide or gallium trichloride, the tellurium compound serves as the halide donor. [Pg.322]


See other pages where Aluminum tribromide, is mentioned: [Pg.295]    [Pg.674]    [Pg.94]    [Pg.564]    [Pg.943]    [Pg.383]    [Pg.51]    [Pg.53]    [Pg.265]    [Pg.450]    [Pg.121]    [Pg.162]    [Pg.280]    [Pg.378]    [Pg.470]    [Pg.450]    [Pg.1503]    [Pg.16]    [Pg.112]   
See also in sourсe #XX -- [ Pg.442 ]




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