Generation, Reactions, and Kinetics of Sterically Congested Triplet Diphenylcarbenes. Effects of Bromine Groups
作者:Hideo Tomioka、Tetsuya Watanabe、Makoto Hattori、Naoki Nomura、Katsuyuki Hirai
DOI:10.1021/ja010658s
日期:2002.1.1
A series of polybrominated diphenylcarbenes (DPCs) are generated by irradiation of the corresponding precursor diazomethanes, and their reactivities are investigated by means of low-temperature spectroscopies as well as laser flash photolysis. Triplet bis(2,4,6-tribromophenyl)carbene was shown to decay by undergoing dimerization and to have a half-life of 1 s in a degassed benzene solution at room
通过辐照相应的前体重氮甲烷生成一系列多溴二苯卡宾 (DPC),并通过低温光谱和激光闪光光解研究了它们的反应性。三重双(2,4,6-三溴苯基)卡宾通过二聚作用发生衰变,室温下在脱气苯溶液中的半衰期为 1 秒,比母体 DPC 的寿命长约 6 个数量级. 注意到对位取代基对三联体稳定性的异常影响。因此,虽然用甲基取代 4-溴基团导致寿命急剧下降,但引入叔丁基导致寿命急剧增加;三元组之二(2, 6-二溴-4-叔丁基苯基)卡宾在室温下在溶液中的半衰期为 16 秒。还描述了通过间溴基团的支撑作用以及溴和甲基的协同作用来增加这些多溴化 DPC 稳定性的尝试。