Description
3-Bromo-9H-carbazole is an isomer to 2-Bromo-9H-carbazole, with the only difference being that 9H-carbazole is mono-brominated at 3-position. Blocked at 3-position, 3-Bromo-9H-carbazole derivatives reduce the chance of being oxidised to form excimers or oligomers. 3-bromo-9H-carbazole is a versatile building block that can be used to create a range of compounds, such as 9-Benzyl-3-bromo-9H-carbazole. 3-Bromo-9H-carbazole can be prepared by reacting 9H-carbzole with N-bromosuccinimide (NBS) In tetrahydrofuran at room temperature[1].
Chemical Properties
White to light yellow solid
Uses
3-Bromo-9H-carbazole is an aryl hydrocarbon receptor agonist. A standard for environmental testing and research. Substance for the bological potency study, characterization of mono to tetra-halogenated carbazoles.
Uses
3-Bromocarbazole is used as a intermediate for organic light-emitting diode(OLED) and pharmaceutical.
Preparation
3-Bromocarbazole synthesis: A solution of N-bromosuccinimide (1.1g, 5.98mmol) in dimethylformamide was added dropwise to a solution of carbazole (1, 1g, 5.96mmol) in dimethylformamide (15mL) at 0°C. The reaction mixture was then stirred at room temperature for 24h. The reaction was poured into distilled water to give a cream coloured precipitate. The precipitate was filtered off under vacuum and washed with distilled water (3 × 20mL). The precipitate was dissolved in ethyl acetate, dried with sodium sulfate and filtered. Upon concentration under reduced pressure the crude product was obtained as a brown solid. After crystallisation of the crude product with chloroform, the pure 3-Bromo-9H-carbazole(692 mg, 47%) was obtained as white crystals. Rf (ethyl acetate/hexane, 1:6 v/v): 0.43; melting point: 200–201°C.
Synthesis
General procedure for the synthesis of 3-bromocarbazole from carbazole: Carbazole (10 g, 59.80 mmol) was added to N,N-dimethylformamide (DMF, 67 mL) and stirred at room temperature for 15 min. A solution of N-bromosuccinimide (NBS, 10.6 g, 59.56 mmol) in DMF (100 mL) was slowly added dropwise at 0 °C. After the dropwise addition was completed, the reaction mixture was gradually warmed up to room temperature and stirring was continued for 2 hours. Upon completion of the reaction, the mixture was poured into water and a white precipitate precipitated. The precipitate was collected by filtration and dissolved in dichloromethane. The organic layer was washed with water to remove water soluble impurities. The organic phase was dried with anhydrous sodium sulfate and concentrated under reduced pressure to remove the solvent. The resulting white solid was purified by ethanol recrystallization to give 3-bromocarbazole in colorless crystalline form (10.65 g, 72% yield). The structure of the product was confirmed by 1H-NMR (CDCl3, 400 MHz) and mass spectrometry (ESI): 1H-NMR δ 8.34 (bs, 1H), 8.15 (d, J = 7.8 Hz, 1H), 7.48 (d, J = 8.2 Hz, 1H), 7.45 (m, 1H), 11.42 (s, 1H); MS (ESI) m/z 246 ( M+).
References
[1] Peng-Mian Huang, Xiao-Chun Wang. “9-Benzyl-3-bromo-9H-carbazole.” Acta crystallographica. Section E, Structure reports online 65 Pt 8 (2009): o1763.
