Organoboron compounds—XVIII Alkylbromoboranes and relative disproportionation tendencies of alkylhaloboranes
作者:P.A. McCusker、J.H. Bright
DOI:10.1016/0022-1902(66)80115-x
日期:1966.10
The disproportionation tendencies of alkylbromoboranes are significantly different from those of the corresponding alkylchloro and alkylfluoro compounds. Alkyldibromoboranes undergo slow thermal disproportionation to boron bromide and trialkylboranes on fractional distillation while alkyldichloro- and difluoroboranes are completely resistant to disproportionation under the same conditions. Dialkylbromoboranes
烷基溴硼烷的歧化倾向与相应的烷基氯和烷基氟化合物的歧化倾向明显不同。烷基二溴硼烷在分馏中经历缓慢的热歧化,生成溴化硼和三烷基硼烷,而烷基二氯和二氟硼烷在相同条件下完全抵抗歧化。二烷基溴硼烷完全抵抗二烷基氟硼烷的热歧化。平衡实验表明,歧化趋势的这些差异是热力学而非动力学因素的结果。伯烷基溴硼烷 通过使合适的化学计算量的溴化硼与伯三烷基硼烷在140°以上反应,可以方便地以高收率制备二烷基溴硼烷或其混合物。三异propylborane,即使在乙硼烷的存在下,不与溴化硼反应,直到广泛异构化异丙酯到Ñ发生丙基的基团。三小号只有部分异构化-butylborane反应,得到纯的二-明显的产率小号-butylbormoborane。