[CH3:1][N:2]1[CH2:7][CH2:6][N:5]([C:8]2[CH:14]=[CH:13][CH:12]=[CH:11][C:9]=2N)[CH2:4][CH2:3]1.N([O-])=O.[Na+].[OH-].[Na+].[BrH:21]>O.[Cu](Br)Br>[Br:21][C:9]1[CH:11]=[CH:12][CH:13]=[CH:14][C:8]=1[N:5]1[CH2:6][CH2:7][N:2]([CH3:1])[CH2:3][CH2:4]1
A solution of 2-(4-methylpiperazin-1-yl)-aniline (23.77 grams, 0.124 mol) in 80 mL of 48% hydrobromic acid was cooled to 20° C. and treated with a solution of sodium nitrite (8.6 grams, 0.124 mol) in 35 mL of water while maintaining a temperature of 20-25° C. To this was added a solution of copper (II) bromide (3.5 grams, 0.024 mol) in 12 mL of 48% HBr. The mixture was heated to 85° C. for approximately 30 minutes, poured over crushed ice in a large beaker and neutralized with dilute aqueous sodium hydroxide. The crude product was extracted into diethyl ether and concentrated in vacuo to a black oil which was chromatographed on silica gel using triethylamine:methanol:methylene chloride (0.5:10:90) as the eluent. The product, 1-bromo-2-(4-methylpiperazin-1-yl)benzene, was obtained as a brown oil, 20 grams. Mass spectrum: 254 (M+), 256. 1H-NMR (CDCl3, 300 MHz) δ7.55 (1H, d), 7.30 (1H, t), 7.05 (1H, d), 6.9 (1H, t), 3.05 (4H, br s), 2.55 (4H, t), 2.35 (3H, s).
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