Isopropanol → 2-Bromoanthracene

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

2-Bromoanthraquinone 10 (8.50 g, 0.0296 mol, 1 equiv) and a 50:50 mixture of isopropyl alcohol and tetrahydrofuran (200 mL) were stirred for 10 minutes at 0° C., forming a yellow suspension. NaBH4 (6.70 g, 0.177 mol, 6.0 equiv.) was added to the suspension at 0° C. The mixture was stirred at 0° C. for three hours, turning red in color. The solution was then warmed to room temperature. Additional NaBH4 (3.35 g, 0.089 mol, 3.0 equiv.) was added to the solution at room temperature and the solution was stirred at room temperature for 12 hours, turning into an orange suspension. Deionized water (10 mL) was added to the solution at room temperature and the solution was stirred at room temperature for an additional 12 hours. The consumption of 2-bromoanthraquinone 10 was monitored by thin-layer chromatography (35% CHCl3/hexane, Rf=0.33). Once the consumption of 2-bromoanthraquinone 10 stopped entirely (it was never fully consumed), the volatiles were removed by rotary evaporation. 3 M HCl was slowly added to the solution until bubbling ceased, then additional 3 M HCl (30 mL) was added. The solution was heated at reflux for 6 hours, turning into an opaque, yellow suspension in the process. The mixture was cooled to room temperature, turning into a transparent solution containing yellow-brown crystals. As much water as possible was removed by rotary evaporation. The contents were then vacuum-filtered and washed using deionized water to remove any water, acid and ionic salt, leaving behind a yellow-brown colored solid. The vacuum-filtration receiving flask was changed and the solid was washed with CH2Cl2 through the filter paper. The CH2Cl2 was removed through rotary evaporation. The remaining solid was purified by column chromatography (100% hexane, Rf=0.27), providing 2-bromoanthracene 11 as a white, powdery solid (2.00 g, 26%). 1H NMR (CDCl3): δ 8.42 (s, 1H), 8.34 (s, 1H), 8.18 (d, 1H), 8.01 (m, 2H), 7.87 (d, 1H), 7.50 (m, 3H).

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