Uses
1,3-Bis(trifluoromethyl)-5-bromobenzene is used to prepare the tetrakis[3,5-bis(trifluoromethyl)phenyl]borate ion, which acts as a stabilizing counterion for electrophilic organic and organometallic cations.
Synthesis
Example 1: 1,3-bis(trifluoromethyl)benzene (1 kg) was slowly added to concentrated sulfuric acid (4 kg) while stirring the reaction mixture. The mixture was cooled to 5°C and 1,3-dibromo-5,5-dimethylglycolide (DBDMH, 668g) was added in batches over a period of 4 hours while maintaining the temperature between 0°C and 10°C. After completion of the reaction, the mixture was allowed to stand and layered to separate the organic phase. The organic phase was washed sequentially with water and dilute sodium bisulfite solution to remove residual acid and oxidants. Finally, the organic phase was purified by fractional distillation to afford 3,5-bis(trifluoromethyl)bromobenzene (1100 g, 99% purity, 80% yield).
References
[1] Journal of Organic Chemistry, 2003, vol. 68, # 9, p. 3695 - 3698
[2] Journal of Organic Chemistry USSR (English Translation), 1991, vol. 27, # 1.2, p. 108 - 112
[3] Zhurnal Organicheskoi Khimii, 1991, vol. 27, # 1, p. 125 - 129
[4] Tetrahedron Letters, 1998, vol. 39, # 52, p. 9621 - 9622
[5] Synlett, 1999, # 8, p. 1245 - 1246
