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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