Bromobenzene formation

Negrel, J. C., Gony, M., Chanon, M., Lai, R. Reactivity of copper metal vapors with substituted bromobenzenes. Formation and molecular structure of Cu(PMe3)3Br. Inorg. Chim. Acta 1993, 207, 59-63. 

The yields" of the Grignard reagents are usually 90% or higher too fast an addition of RBr, however, may result in the formation of substantial amounts of R-R, especially in the case of bromobenzene. 

Another method for the hydrogenoiysis of aryl bromides and iodides is to use MeONa[696], The removal of chlorine and bromine from benzene rings is possible with MeOH under basic conditions by use of dippp as a ligand[697]. The reduction is explained by the formation of the phenylpalladium methoxide 812, which undergoes elimination of /i-hydrogen to form benzene, and MeOH is oxidized to formaldehyde. Based on this mechanistic consideration, reaction of alcohols with aryl halides has another application. For example, cyclohex-anol (813) is oxidized smoothly to cyclohexanone with bromobenzene under basic conditions[698]. 

Suitable substrates for the Hunsdiecker reaction are first of all aliphatic carboxylates. Aromatic carboxylates do not react uniformly. Silver benzoates with electron-withdrawing substituents react to the corresponding bromobenzenes, while electron-donating substituents can give rise to formation of products where an aromatic hydrogen is replaced by bromine. For example the silver /)-methoxybenzoate 6 is converted to 3-bromo-4-methoxybenzoic acid 7 in good yield ... 

Phenylnaphthalene has been prepared by the reaction of a-halonaphthalenes with mercury diphenyl3 6 or with benzene in the presence of aluminum chloride,6 and by means of the Gri-gnard synthesis, starting with either bromobenzene, cyclohexyl chloride, and a-tetralone 7 or with a-bromonaphthalene and cyclohexanone.6 8 9 Dehydrogenation of the reduced naphthalene has been accomplished by the use of sulfur,6 bromine,8 platinum black, or selenium.7 The formation of the hydrocar-... 

The first Pd-catalyzed C—N bond formation was described by the Migita group in 1983. They cross-coupled bromobenzene with N, N-diethylaminotributyltin to prepare N,N-... 

A detailed investigation of the Ni-dppe catalyzed formation of biphenyl from bromobenzene has resulted in the proposal of a catalytic cycle (Scheme 1) in which the tr-aryl-nickel intermediate is first reduced into the corresponding ArNi then transformed into a diaryl-nickel(III) complex. This complex then undergoes a reductive elimination leading to the product and Ni, followed by the regeneration of the Ni system [32, 34],... 

Very few transition-metal catalyzed electroreductive carbon-heteroatom bond formations have been described. The electrochemical silylation of allylic acetates was carried out in the presence of Pd-PPha [131]. The electrosynthesis of arylthioethers from thiophenol and aryl halides [132] and the coupling of bromobenzene with dichlorophenylphosphine [133] were performed with Ni-bpy as catalyst. 

EINECS 203-468-6, see Ethylenediamine EINECS 203-470-7, see Allyl alcohol EINECS 203-472-8, see Chloroacetaldehyde EINECS 203-481-7, see Methyl formate EINECS 203-523-4, see 2-Methylpentane EINECS 203-528-1, see 2-Pentanone EINECS 203-544-9, see 1-Nitropropane EINECS 203-545-4, see Vinyl acetate EINECS 203-548-0, see 2,4-Dimethylpentane EINECS 203-550-1, see 4-Methyl-2-pentanone EINECS 203-558-5, see Diisopropylamine EINECS 203-560-6, see Isopropyl ether EINECS 203-561-1, see Isopropyl acetate EINECS 203-564-8, see Acetic anhydride EINECS 203-571-6, see Maleic anhydride EINECS 203-576-3, see m-Xylene EINECS 203-598-3, see Bis(2-chloroisopropyl) ether EINECS 203-604-4, see 1,3,5-Trimethylbenzene EINECS 203-608-6, see 1,3,5-Trichlorobenzene EINECS 203-620-1, see Diisobutyl ketone EINECS 203-621-7, see sec-Hexyl acetate EINECS 203-623-8, see Bromobenzene EINECS 203-624-3, see Methylcyclohexane EINECS 203-625-9, see Toluene EINECS 203-628-5, see Chlorobenzene EINECS 203-630-6, see Cyclohexanol EINECS 203-632-7, see Phenol EINECS 203-686-1, see Propyl acetate EINECS 203-692-4, see Pentane EINECS 203-694-5, see 1-Pentene EINECS 203-695-0, see cis-2-Pentene EINECS 203-699-2, see Butylamine EINECS 203-713-7, see Methyl cellosolve EINECS 203-714-2, see Methylal EINECS 203-716-3, see Diethylamine EINECS 203-721-0, see Ethyl formate EINECS 203-726-8, see Tetrahydrofuran EINECS 203-729-4, see Thiophene EINECS 203-767-1, see 2-Heptanone EINECS 203-772-9, see Methyl cellosolve acetate EINECS 203-777-6, see Hexane EINECS 203-799-6, see 2-Chloroethyl vinyl ether EINECS 203-804-1, see 2-Ethoxyethanol EINECS 203-806-2, see Cyclohexane EINECS 203-807-8, see Cyclohexene EINECS 203-809-9, see Pyridine EINECS 203-815-1, see Morpholine EINECS 203-839-2, see 2-Ethoxyethyl acetate EINECS 203-870-1, see Bis(2-chloroethyl) ether EINECS 203-892-1, see Octane EINECS 203-893-7, see 1-Octene EINECS 203-905-0, see 2-Butoxyethanol EINECS 203-913-4, see Nonane EINECS 203-920-2, see Bis(2-chloroethoxy)methane EINECS 203-967-9, see Dodecane EINECS 204-066-3, see 2-Methylpropene EINECS 204-112-2, see Triphenyl phosphate EINECS 204-211-0, see Bis(2-ethylhexyl) phthalate EINECS 204-258-7, see l,3-Dichloro-5,5-dimethylhydantoin... 

In the presence of Priedel-Crafts catalysts (BF3, FeClj, and others), comparatively less reactive compounds, such as benzene (50°C, 2 hr) and toluene (100°C, 4 hr), can be reacted in an autoclave with GFsSCl to give CjHs—SCFs or a mixture of m- andp-CFsS—CgHaCHs, respectively. Ghloro- and bromobenzene react under more vigorous conditions (200°G, 2 hr) with the formation of a mixture of ortho-, meta-, and para- THF, tetrahydrofuran. 

Successful lithiation of aryl halides—carbocyclic or heterocyclic—with alkyUithiums is, however, the exception rather than the rule. The instability of ortholithiated carbocyclic aryl halides towards benzyne formation is always a limiting feature of their use, and aryl bromides and iodides undergo halogen-metal exchange in preference to deprotonation. Lithium amide bases avoid the second of these problems, but work well only with aryl halides benefitting from some additional acidifying feature. Chlorobenzene and bromobenzene can be lithiated with moderate yield and selectivity by LDA or LiTMP at -75 or -100 °C . 

Yoshida et al. [63] applied microreaction technology for the sequential synthesis and the disubstitution of o-bromophenyUithiuni (Scheme 28). Lithiation of o-dibromobenzene in batch leads to the formation of the highly reactive benzyne and to the further creation of various side products thus this reaction needs to be conducted at 100°C and below to avoid this problem. This reaction was optimized under microreactor conditions for the production of o-bromophenyUithium and for its further reaction with methanol to determine the yield of bromobenzene. Microreactors were set up of stainless steel tubes with an internal diameter of 250-1,000 pm. 

The choice of an ionic liquid was shown to be critical in experiments with [NBuJBr (TBAB, m.p. 110°C) as a catalyst carrier to isolate a cyclometallated complex homogeneous catalyst, tra .s-di(ri-acetato)-bis[o-(di-o-tolylphosphino) benzyl] dipalladium (II) (Scheme 26), which was used for the Heck reaction of styrene with aryl bromides and electron-deficient aryl chlorides. The [NBu4]Br displayed excellent stability for the reaction. The recycling of 1 mol% of palladium in [NBu4]Br after the reaction of bromobenzene with styrene was achieved by distillation of the reactants and products from the solvent and catalyst in vacuo. Sodium bromide, a stoichiometric salt byproduct, was left in the solvent-catalyst system. High catalytic activity was maintained even after the formation of visible palladium black after a fourth run and after the catalyst phase had turned more viscous after the sixth run. The decomposition of the catalyst and the formation of palladium... 

As the last example of C-C bond-formation reactions catalyzed by alkaline earth hydroxides, we mention the recently reported a-arylation of diethyl malonate in the presence of a palladium catalyst and a base in a separate phase 299). The arylation of carbonyl compounds is a carbon-carbon coupling reaction between an aryl halide and an enolate, which is usually catalyzed by palladium salts in the presence of an appropriate base (300,301). The arylation of diethyl malonate with bromobenzene (Scheme 48) was performed with tetrachloropalladate as the... 

The formation of bromophenylmercapturic acid from bromobenzene and cystine in the organism, if it had the formula given it by Baumann now seemed scarcely possible, unless an isomeric a-thio-y8-aminopropionic acid were also present in the protein molecule together with the di-/8-thio-a-aminopropionic acid or cystine. The investigation of their constitution was therefore taken up by Friedmann in 1904, who succeeded in showing that they were also derived from -thio-a-aminopropionic acid and not from the isomeric a-thio-/8-aminopropionic acid. 

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