Bromo Bromoaniline

Add 20 g. of /)-bromoaniline to 20 ml. of water in a 250 ml. beaker, and warm the mixture until the amine melts. Now add 23 ml. of concentrated hydrochloric acid and without delay stir the mixture mechanically in an ice-water bath, so that a paste of fine /> bromo-aniline hydrochloride crystals separates. Maintain the temperature of the stirred mixture at about 5° whilst slowly adding from a dropping-funnel a solution of 8 5 g. of sodium nitrite in 20 ml. of water con tinue the stirring for 20 minutes after the complete addition of the nitrite. 

The p-bromoaniline separates as an oil, which soon sohdifies. Filter at the pump and wash with cold water. Purify the crude p-bromoanihne aa follows. Dissolve it in a mixture of 120 ml. of water and 75 ml. of concentrated hydrochloric acid, add 1-2 g. of decolourising carbon, and warm on a water bath for 10 minutes. Filter through a fluted paper or through two thicknesses of filter paper on a Buchner funnel. Pour the filtrate slowly and with vigorous stirring into a mixture of 60 ml. of 10 per cent, sodium hydroxide solution and 100 g. of crushed ice. Thep-bromo-aniline crystallises out. Filter, etc. as in Method 1. The yield is 11 5 g. 

The oil, which is heavier than water, is separated, and the aqueous layer is extracted with three 50-ml. portions of methylene chloride. The oil and extracts are combined, dried over anhydrous sodium sulfate, and distilled from a Claisen flask with an indented neck. Colorless l-bromo-2-fluorobenzene is collected at 58-59°/17 mm. or 156—157°/760 mm. weight 45-47 g. (73— 75% based on o-bromoaniline) d 1.5320-1.5325. 

The checkers have prepared the following bromides by the same procedure w-chlorobromobenzene (b.p. 191-194°) from jw-chloroaniline in 91-94% yields ra-dibromobenzene (b.p. 215-217°) from ra-bromoaniline in 80 87% yields and u-bromo-anisole (b.p. 114-116°/29 mm.) from o-anisidine in 88-93% yields. In the preparation of o-bromoanisole the washing with sulfuric acid was omitted. 

If the bromination of phenylaminomethylenemalonates was carried out in acetic acid with bromine, only substitution of the aromatic ring occurred and, depending on the molar ratio and the reaction period, p-bromo or o,p-dibromo derivatives were obtained (57JIC817). From /V-(w-nitrophe-nyl)aminomethylenemalonate, only 3-nitro-6-bromoaniline was obtained. 

Bromochloroaniline, see o-Bromoaniline Bromochloromethane, see Dibromochloromethane Bromochloronaphthalene, see Naphthalene l-Bromo-3-chloropropan-2-one, see l,2-Dibromo-3-chloropropane... 

Prenylaniline (945) required for the synthesis of (+ )-carquinostatin A [( )-278] (see retrosynthesis in Scheme 5.126) was obtained by a nickel-mediated cross-coupling reaction of the N-protected 4-bromoaniline 952 with bis[n-bromo(r -prenyl)nickel] (825) (646) (Scheme 5.128). 

Bromo-4-acetaminotoluene, 593, 605 p-Bromoacetanilide, 577, 580 p - Bromoace tophenone. 726, 732 m-Bromo-p-acetotoluidido, 593, 605 3-Bromo-4-aminotoluene, 593, 605 hydrochloride, 605 p-Bromoanilides, 361 p-Bromoaniline, 577, 580 o-Bromoanisole, 404 p-Bromobenzaldehyde, 689, 694, 696 diacetate, 696... 

Mononitrobromocmiline, (p2>j)Br.C6H3.NH2 mw 217.91%. Seven isomers are described in the literature 4-Nttro-2-bromo-aniline, yel ndls, mp 104.5 4-Nitro-3 bromoaniline, crysts(from ale), mp 175-6° 2-Nitro-4-bromoaniline, om-yel ndls(from boiling w), mp 111.5° 3-Nitro-4 -bromoaniline, flat ndls (from ale), mp 131° 2-Nitro-5-bromoaniline, red-yel ndls, mp 151-2° 2-Nitro-6-bromoaniline, yel ndls(from dil ale), mp 73-5° and 3-Nitro-6-bromoaniline, yel ndls (from ale), mp 141°. Some of these isomers form salts addn compds, some of which are volatile and unstable. 

Another side reaction which occurs is reduction in the reaction the —N2C1 or —N(NO)COCH3 group is replaced by hydrogen. wi-Bromo-toluene was isolated in 6% yield from the reaction between the sodium diazotate from 2-bromo-4-methylaniline and benzene, and in 10% yield in a similar reaction from 2-methyl-4-bromoaniline.4 Some nitrobenzene is obtained in the preparation of 3-nitrobiphenyl from nitroso-w-nitro-acetanilide (p. 250). The source of the hydrogen effecting the reduction has not been determined. f... 

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