Bromobenzene lithium

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. 

Bromobenzene was added to lithium in an ethereal medium to obtain phenyl-lithium. 

In a modified preparation of phenyllithium, bromobenzene was added to finely powdered lithium (rather than coarse particles) in ether. The reaction appeared to be proceeding normally, but after about 30 min it became very vigorous and accelerated to explosion. It was thought that the powdered metal may have been partially coated with oxide or nitride which abraded during stirring, exposing a lot of fresh metal surface on the powdered metal. 

Chloroform Metals Iodomethane Sodium Lithium Bromobenzene See entry METAL-HALOCARBON INCIDENTS... 

While a current of dry nitrogen is passed through the apparatus, 400 cc. of dry ether and 6.9 g. (1 gram atom) of lithium (in small pieces) (Note 1) are placed in a 1-1. three-necked flask fitted with a dropping funnel, mechanical stirrer, and reflux condenser protected from moisture. The. stirrer is started, and 10-15 cc. of a solution of 79 g. (0.5 mole) of dry bromobenzene in 100 cc. of dry ether is added from the dropping funnel. The reaction usually starts immediately if not, the flask may be warmed, and the remainder of the mixture is then added at such a rate that the ether refluxes gently. The mixture is stirred until the lithium disappears (Note 2). 

So far, many syntheses of p, or m-silylphenol derivatives were reported(56-60). p-Trimethylsilyloxy trimethylsilyl benzene was synthesized from trimethylsilyl chloride and p-trimethylsilyloxychloro(or bromo)benzene in the presence of Mg, or Na(56,57,59,60). A similar compound was also synthesized from triphenylchlorosilane and p-lithio phenoxy lithium(58). m-Trimethylsilyloxytrimethylsilylbenzene was prepared from m-trimethylsilyloxy bromobenzene and trimethylsilylchloride(59). 

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 . 

Phenylpiperidine has been prepared by warming aniline with 1,5-dibromopentane 4,8 heating 5-anilino-l-bromopentane 6 the dehydration of 5-anilino-l-pentanol over alumina 7 the electrolytic reduction of N-phenylglutarimide 8 the catalytic hydrogenation of l-phenyl-3-hydroxypyridinium chloride 9 the action of bromobenzene on piperidine in the presence of lithium 10 the reaction of fluorobenzene, 1-methylpiperidine, and phenyl-lithium 11 the action of diphenylsulfone on piperidine in the presence of sodamide 12 the diazotization and deamination of l-(2-aminophenyl)piperidine 13 and of l-(4-aminophenyl)piperidine 14 and the present method.18... 

Another route to anthraquinones has been devised which relies on the addition of carbanions (22) derived from phthalides to arynes (81JCS(P1)2120). For the formation of anthraquinone (23) itself, phthalide was treated with 2.2 equivalents of lithium diisopropyl-amide in THF. Bromobenzene was then added and the reaction mixture warmed to room... 

Cognate preparation. 3,3,5-Trimetkyl-l-methylenecyclohexane. Prepare an ethereal solution of phenyllithium by the procedure described in Expt 8.32, using 2.7 g (0.39 mol) of lithium shavings, 26 g (17.5 ml, 0.16 mol) of dry redistilled bromobenzene and 85 ml of anhydrous ether. After the conversion to phenyllithium is complete dilute the solution with a 15 ml portion of anhydrous ether and decant the solution from any unreacted lithium [Expt 8.32 Note (2)] into a clean three-necked 250-ml flask equipped with a nitro-... 

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