Application
2,5-Dibromoiodobenzene is a very important fine chemical raw material. It belongs to the halogenated derivatives of benzene and is a white solid. It is mainly used in the synthesis of pharmaceuticals, pesticides, dyes, plastics and functional polymer materials.
Synthesis
General procedure for the synthesis of 2,5-dibromoiodobenzene from 2,5-dibromoaniline: 2,5-dibromoaniline (10 g) was suspended in dilute hydrochloric acid (prepared by mixing 40 ml of concentrated hydrochloric acid with 30 ml of water), cooled down to 0°C, and then an aqueous solution of sodium nitrite (NaNO2, 3 g) was slowly added dropwise. The reaction mixture was continuously stirred at 0°C for 40 min to complete the diazotization reaction. Subsequently, the diazonium salt solution was slowly added to a pre-prepared aqueous solution of potassium iodide (60 g) at room temperature. The reaction mixture was stirred for 2 hours at room temperature to induce complete iodination reaction. After completion of the reaction, the organic layer was separated by adding dichloromethane and a small amount of sodium bisulfite for extraction. The organic layer was washed sequentially with 10% aqueous sodium bisulfite and saturated saline to remove residual iodine and acid. The washed organic layer was dried with anhydrous sodium sulfate, filtered and distilled under reduced pressure to remove the solvent. Finally, the crude product was purified by silica gel column chromatography to afford 10.5 g of 2,5-dibromoiodobenzene in white crystalline form in 73% yield.
References
[1] Patent: EP1707550, 2006, A1. Location in patent: Page/Page column 36
[2] Patent: CN107523089, 2017, A. Location in patent: Paragraph 0024; 0025; 0026; 0035; 0044
[3] Patent: CN107739529, 2018, A. Location in patent: Paragraph 0020; 0039; 0040; 0041
[4] Macromolecules, 2004, vol. 37, # 21, p. 7867 - 7878
[5] New Journal of Chemistry, 2018, vol. 42, # 8, p. 5767 - 5773
