4-bromobenzene-, sodium

SAFETY PROFILE Moderately toxic by intraperitoneal route. Mildly toxic by inhalation. Dangerous fire hazard when exposed to heat, flame, or oxidizers. Violent reaction with bromobenzene + sodium above 30°C. Can react with oxidizing materials. To fight fire, use CO2, dry chemical, mist or spray. See also BROMIDES. 

Even though the reaction conditions may lead to formation of the metal enolate in high yield, further reduction may occur during the quenching step of the reaction. Alcohols such as methanol and ethanol convert metal enolates to saturated ketones much faster than they react with metals in ammonia, and quenching of reduction mixtures with these alcohols will usually lead to partial or complete conversion to alcoholic product rather than to the saturated ketone. Rapid addition of excess solid ammonium chloride is the commonly employed quench procedure if ketonic products are desired,but other reagents that destroy solvated electrons before neutralization may be employed, such as sodium ben-zoate, iron(III) nitrate, - sodium nitrite, bromobenzene, sodium bromate, 1,2-dibromoethane and acetone. 

Halogen, Chloral hydrate, sodium chloroacetate, chlorobenzene, />-chlorophenol, dichlorhydrin, bromobenzene, iodobenzene. 

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). 

Method 2. Transfer the dark-coloured reaction product to a separatory funnel and shake successively with water, with sufficient 5-10 per cent, sodium hydroxide solution to ensure that the washings are alkaline to litmus, and finally with water. Dry with anhydrous magnesium sulphate or calcium chloride. Filter through a fluted filter paper into a small distilling flask and distil slowly. Collect the crude bromobenzene at 150-170° pour the residue whilst still hot into a small porcelain basin. Redistil the hquid of b.p. 150-170° (3) and collect the bromobenzene at 154-157° the yield is about 60 g. 

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. 

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. ... 

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. 

Timolol maleate a-Bromoacetophenone Nomifensine maleate Bromoacetyl bromide Bromazepam Cephapirin sodium Clonazepam Flunitrazepam 5-Bromoacetyl salicylamide Labetalol HCI m-Bromoanisole Tramadol HCI p-Bromoanisole Cyclofenil 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 same happened with the reaction of bromobenzene with finely divided sodium. The less risky method consists in using sodium wire in benzene or toluene. 

The Wurtz reaction between bromobenzene and 1-bromobutane, sodium being the metal, needs to be carried out between 15 and 30°C. It is difficult to start the reaction below 15°C starting compounds will accumulate and the delayed start in a halogen medium, which is too concentrated, will lead to a detonation. Above 30°C the reaction is too violent and cannot be controlled. 

Some of the details of the mechanism may differ for various catalytic systems. There have been kinetic studies on two of the amination systems discussed here. The results of a study of the kinetics of amination of bromobenzene using Pd2(dba)3, BINAP, and sodium r-amyloxide in toluene were consistent with the oxidative addition occurring after addition of the amine at Pd. The reductive elimination is associated with deprotonation of the animated palladium complex.166... 

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