2-Amino-6-bromonaphthalene

P-Bromonaphthalene. The preparation from p-naphthylamine, which has carcinogenic properties, is avoided by the use of 2-naphthylamine-1-sulphonic acid ( 2-amino-1-naphthalenesulphonic acid ) the latter is obtained commercially by cautious treatment of p-naphthol with sulphuric acid—the SOjH group first enters the 1-position—followed by the Bucherer reaction. Diazotisation and reaction with cuprous bromide yields 2-bromonaphthalene-l-sulphonic acid heating with sulphuric acid eliminates the sulphonic acid group to give 2-bromonaphthalene. 

The pale yellow colour cannot be removed by redistillation or recrystallisation the coloured product probably contains some amino compound rendering it unsuitable for conversion into a Grignard reagent. A pure white product may be obtained by the following procedure. Dissolve 50 g of the coloured compound in 200 ml of hexane and pass the solution through a column of activated alumina (80-200 mesh dimensions about 9 cm x 3 cm) wash the column with 750 ml of hexane. Remove the hexane by distillation 49 g of pure 2-bromonaphthalene, m.p. 58 °C, remains. This is sufficiently pure for use in Grignard reactions. 

Replacement of the diazo group by hydrogen has been reported for a number of diazo oxides. For example, the diazo oxide from 2-nitro-4-aminophenol yields o-nitrophenol in 53% yield,42 - 43 and that from 1-amino-2-hydroxy-6-bromonaphthalene-4-sulfonic acid gives XV in approximately 50% yield.44... 

The syntheses of benzo[e] and benzo[g]indoles have been performed by reaction of 2-amino-1-bromo or l-amino-2-bromonaphthalene with the anion of pinacolone (67% and 82% yields, respectively). The reaction with the anion CH2COCH(OMe)2, affords the 2-formyl indoles (52% and 65% yields, respectively), which can be oxidized to the corresponding acids [90]. 

The benzonaphthothiazocine 559 was obtained from l-amino-8-bromonaphthalene 599, which by acetylation with Ac20 furnished the corresponding acetyl derivative 600. This latter compound was coupled with thiosalicylic acid to give thioether 601 that was converted into the polycondensed thiazocine 559 by initial formation of acyl chloride and subsequent cyclization to the lactam (Scheme 120) <1996JST(382)1>. 

The bromonaphthalenes, 56, have a pH-controlled phosphorescence. At pH lower than ground-state pA , the protonation of the amino group hampers the quenching of the bromonaphthyl moiety emission by the electron-transfer process. The addition of 5 x 10" P-CD caused a... 

Amino derivatives of anthraquinone should be chromatographed in the following systems 1-bromonaphthalene/pyridine-water (2 1 and 1 1)... 

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