Synthesis
The general procedure for the synthesis of 2,5-dibromo-3-hexylthiophene from 3-hexylthiophene is as follows: first, 1070 g of a 48% solution of hydrobromic acid was added to 338 g of 3-hexylthiophene. The reaction mixture was cooled to -5 °C and 400 g of a 34% hydrogen peroxide solution was added slowly and dropwise over a period of 7 hours. After the dropwise addition was completed, the reaction mixture was gradually warmed to 20°C over 16 hours. After completion of the reaction, phase separation was carried out. The resulting crude product 2,5-dibromo-3-hexylthiophene had a purity of 96.9% and a yield of 97%.
References
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[3] Patent: US2009/259053, 2009, A1. Location in patent: Page/Page column 1
[4] Bulletin of the Chemical Society of Japan, 1995, vol. 68, # 8, p. 2363 - 2378
[5] New Journal of Chemistry, 2001, vol. 25, # 2, p. 318 - 321
