Alkylation aluminum bromide

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 ... 

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... 

Examples of w-allylnickel-X compounds (X = anionic ligand) other than 77-allylnickel halides which have been used in combination with (alkyl)aluminum halides as olefin oligomerization catalysts are 7r-allyl-nickel acetylacetonate (11) (Section III), 7r-allylnickel aziridide (4, 56), and bis(7r-allyl)nickel (6) (59). In addition to ir-allylnickel halides, organo-nickel halides such as tritylnickel chloride (60, 61) and pentafluoro-phenylbis(triphenylphosphine)nickel bromide (62), or hydridonickel halides, e.g., trans-hydridobis(triisopropylphosphine)nickel chloride (12) (Section III), give active catalysts after activation with aluminum halides... 

Reactions, e.g., with alkyl halides in ether using Ziegler-Natta catalyst form alkyl aluminum halides, R3AI2X3, [R2A1X]2 and [RA1X]2 with bromine vapor forms anhydrous aluminum bromide,... 

Other effects of the ionicity of the catalyst on its activity has been studied by Natta, PaSQUON, Zambelli and Gatti (66). The polymerization of propylene was carried out with alpha titanium trichloride and diethylberylium or triethylaluminum. They found that catalysts from the alkylberylium were more stereospecific than those from alkyl aluminum. On the other hand their study of titanium trichloride with diethylaluminum iodide, diethylaluminum bromide, diethylaluminum chloride or triethylaluminum showed that the greater stereospecificity was produced by the iodide containing catalyst. The less electrophilic catalyst produced greater crystallinity than the corresponding bromide or chloride component. 

Brown, H. C., Jungk, H. The catalytic halides. XI. The isomerization of o- and p-xylenes and some related alkylbenzenes under the influence of hydrogen bromide and aluminum bromide the relative isomerization aptitudes of alkyl groups. J. Am. Chem. Soc. 1955, TT, 5579-5584. 

Preparation from boron trifluoride and aluminum bromide. Cleavage of an ether is effected by adding BBrj to the ice-cold ether (3 equiv.), refluxing the mixture, and removing the alkyl bromide the orthoboric ester is then hydrolyzed with 10% 3 n-Bu—O—Bu-n + BBr, —(n-BuO)jB+3n-BuBr... 

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