Bromobenzene preparation

Bromobenzene,Cf,HfSr. B.p. 155°C. Prepared from benzene by direct bromination in the presence of a carrier (Ij, Fe, AICI3) or by... 

Ullman reaction The synthesis of diaryls by the condensation of aromatic halides with themselves or other aromatic halides, with the concomitant removal of halogens by a metal, e.g. copper powder thus bromobenzene gives diphenyl. The reaction may be extended to the preparation of diaryl ethers and diaryl thio-ethers by coupling a metal phenolate with an aryl halide. 

The fact that n-butylbenzene can be prepared in reasonable yield by the action of sodium upon a mixture of bromohenzene and n-butyl bromide can be partly explained on the assumption that n-butyl bromide reacts with phenyl-sodium more rapidly than does bromobenzene. It is interesting to note that n-butylbenzene can be prepared either from benzylsodium and n-propyl bromide or from phenylsodium and n-butyl bromide (Section VI,29). 

Propiophenone. Prepare a solution of diphenyl-cadmium in 110 ml. of dry benzene using 4 9 g. of magnesium, 32 4 g. of bromobenzene and 19 5 g. of anhydrous cadmium chloride. Cool the solution to 10°, and add during 3 minutes a solution of 14 -8 g. of propionyl chloride (b.p. 78-79°) in 30 ml. of dry benzene use external coohng with an ice bath to prevent the temperature from rising above 40°. Stir the mixture for 2 hours at 25-35°. Work up the product as detailed above except that 6 per cent, sodium carbonate solution should replace the saturated sodium bicarbonate solution. The yield of propiophenone, b.p. 100-102°/16 mm., is 17 6 g. 

Solutions of dinitrogen pentoxide have been used in preparative nitrations.Benzene, bromobenzene, and toluene were nitrated rapidly in solutions of the pentoxide in carbon tetrachloride nitrobenzene could not be nitrated under similar conditions, but reacted violently with solid dinitrogen pentoxide. 

The preparation of the bromobenzodioxole or bromobenzene is going to be the same no matter which one is used and no matter which precursor the chemist wishes to make. This means that this first part needs to be done correctly. This first part of preparation that Strike is talking about is the creation of a Grignard reagent out of the bromo compound starting material [125,131-134]. Mr. Grignard earned a Nobel prize for this in 1912 so you can bet that it s a pretty good procedure. 

To a mixture of 100 ml of THF and 0.10 mol of the epoxide (note 1) was added 0.5 g Of copper(I) bromide. A solution of phenylmagnesium bromide (prepared from 0.18 mol of bromobenzene, see Chapter II, Exp. 5) in 130 ml of THF was added drop-wise in 20 min at 20-30°C. After an additional 30 min the black reaction mixture was hydrolysed with a solution of 2 g of NaCN or KCN and 20 g of ammonium chloride in 150 ml of water. The aqueous layer was extracted three times with diethyl ether. The combined organic solutions were washed with water and dried over magnesium sulfate. The residue obtained after concentration of the solution in a water-pump vacuum was distilled through a short column, giving the allenic alcohol, b.p. 100°C/0.2 mmHg, n. 1.5705, in 75% yield. 

Phenylmagnesium bromide (2.8 mol) was prepared in anhydrous ether (21) from bromobenzene (440 g, 2.9 mol) and magnesium turnings (68.0 g 2.8 g-atom). To this solution was added dropwise a solution of indole (328 g, 2.8 mol) in benzene (8(X)ml). The resulting solution was stirred for 10 min and then a solution of cyclopentanoyl chloride (322 g, 2.4 mol) in benzene (800 ml) was added dropwise. The solution was stirred for 1 h and then water (11) was added carefully. The precipitate which formed was collected by filtration and dried to give 169 g of crude product. Additional product (97 g) was obtained by evaporation of the organic layer of the filtrate. The combined products were recrystallized from toluene to give 250 g (49% yield) of pure product. 

According to the usual procedure for preparing bromobenzene bromine is added to ben zene in the presence of metallic iron (customarily a few carpet tacks) and the reaction mixture is heated... 

C. It can be obtained from its hahde-free solutions in cyclohexane and ethylether by vacuum distUlation to remove the ether. The usual preparative method is by reaction of chloro- or bromobenzene and lithium metal in ethyl ether or in a mixture of ethyl ether and cyclohexane. 

Salicyl-u-toluide has been prepared only by the action of phosphorus oxychloride upon a mixture of salicylic acid and o-toluidine. The useful methods of preparation of salicylanilide are by the interaction of salicylic acid and aniline in the presence of phosphorus trichloride, by heating phenyl salicylate and aniline, and from o-hydroxybenzamide and bromobenzene in the presence of small amounts of sodium acetate and metallic copper. A number of these and other anilides have been described. ... 

Aj Preparation of (2-Amino-5-ChlorophenyljPhenylmethaneimine (4356 CB) A solution of 228.7 g (1.5 mols) of 2-amino-5-chlorobenzonitrile in 1,800 ml of dry ether is added slowly in the course of about 3.5 hours to a solution of phenyl magnesium bromide prepared from 109 g (4.5 g-atoms) of magnesium turnings and 848 g (5.4 mols) of bromobenzene In 3,600 ml of anhydrous ether, and the mixture then heated under reflux for 15 hours. 

The manufacture of the cyclohexyl analog is as follows. Phenyl magnesium bromide was prepared from 48.5 g (0.308 mol) of bromobenzene, 7 g (0,29 mol) of magnesium, and 125 ml of dry ether. To it was added at 5°C over a period of A hour 40 g (0.18 mol) of cyclohexyl (3-(N-piperidyl)-ethyl ketone (BP 115° to 117°C/1 mm) in 125 ml of dry ether. The mixture was allowed slowly to come to room temperature, refluxed for one hour, and then poured into ice containing 80 ml of concentrated hydrochloric acid. Ammonium chloride (100 g) and 200 ml of concentrated ammonium hydroxide were added and the organic layer was separated. After drying and removing the solvent, the residue was distilled under reduced pressure. The base distilled at 158° to 170°C (1 mm) and solidified. Upon recrystallization from methanol it melted at 112° to 113°C. 

The residue was dissolved in 75 ml of tetrahydrofuran, treated with charcoal, and sodium sulfate and filtered. This solution was added to a solution in 250 ml of tetrahydrofuran of phenyl magnesium bromide prepared from 17.7 ml (0.17 mol) of bromobenzene. This mixture was stirred and heated under reflux for 1 hour. It was then cooled and diluted with 400 ml of ether and sufficient 3N hydrochloric acid to make it acidic. The aqueous phase was separated, adjusted to pH 8 with 3N sodium hydroxide and extracted 3 times with 200 ml of ether. The ether extracts were combined, washed with water and dried over sodium sulfate. The residue left on removal of the ether in vacuo was crystallized from petroleum ether to give 3.3 g of 7-chloro-2,3-dihvdro-1-methyl-5-phenvl-1 H-1,4-benzodiazepine, according to U.S. Patent 3,624,703. 

To the Grignard reagent prepared from 0.59 part of magnesium, 3.95 parts of bromobenzene... 

This procedure is a modification of the method of Goldberg and Nimerovsky.1 Triphenylamine has also been prepared by the treatment of aniline or diphenylamine with potassium and then bromobenzene 2 and by the action of sodium on diphenylamine and bromobenzene.3... 

The present method of preparation of 4,4 -dimethyl-l,l -biphenyl is that described by McKillop, Elsom, and Taylor 15 It has the particular advantages of high yield and manipulative simplicity and is, moreover, applicable to the synthesis of a variety of symmetrically substituted biaryls 3,3 - and 4,4 -Disubstituted and 3,3, 4,4 -tetrasubstituted 1,1 -biphenyls are readily piepared, but the reaction fails when applied to the synthesis of 2,2 -disubstituted-l,T biphenyls The submitters have effected the following conversions by the above procedure (starting aromatic bromide, product biphenyl, % yield) bromobenzene, biphenyl, 85,1 -bromo-4-methoxybenzene, 4,4 -dimethoxy-l, 1 -biphenyl, 99, 1 bromo 3 methylbenzene, 3,3 dimethyl-1,l -biphenyl, 85 4-bromo-l,2-dimethylbenzene, 3,3, 4,4 -tetramethyl-l,l -biphenyl, 76, l-bromo-4-chlorobenzene, 4,4 -dichloro-l,l -biphenyl, 73, l-bromo-4-fluorobenzene, 4,4 -difluoro-l,l -biphenyl, 73... 

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