4,4''-Dibromo-2,2’-diiodobiphenyl (CAS# 852138-89-7) is a useful building block, and is seen in the preparation of hybrid organic/inorganic heterofluorene polymers and in low band-gap polymers for use in photovoltaics.
Synthesis of 4,4'-Dibromo-2,2'-diiodobiphenyl A solution of diamine (16.0 g, 46.8 mmol) and concentrated HCl (56.0 mL) in water (64.0 mL) was cooled to 0 ??C. Next, 8.0g (116 mmol) of NaNO2 in 40 mL of water was added dropwise to the diamine solution over a period of 30 min, keeping the temperature at 0 ??C. After the addition of NaNO2 was complete, the resulting mixture was stirred for an additional 30 min. and an aqueous solution of KI (77.7 g in 150 mL of water) at-5 ??C was added dropwise over 30 min. The reaction mixture was then stirred (by mechanical stirrer) for 1h at r.t and 3 h at 60 ??C, giving a dark brown solution. The solution was then cooled to 25 ??C and the brown precipitate was collected by filtration. The crude brown solid was then purified by column chromatography (silica gel, hexane). The title compound as a white solid (7.4 g, 28 % yield). 1H NMR (CDCl3): |? (ppm) 7.04 (2H, d), 7.57 (2H, d), 8.11 (2H, s).
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