The Identity of the Chain-Carrying Species in Brominations with N-Bromosuccinimide: Selectivity of Substituted N-Bromosuccinimides toward Substituted Toluenes
The Identity of the Chain-Carrying Species in Brominations with N-Bromosuccinimide: Selectivity of Substituted N-Bromosuccinimides toward Substituted Toluenes
复制标题
N-溴代琥珀酰亚胺溴化中带链物质的特性：取代的 N-溴代琥珀酰亚胺对取代甲苯的选择性
DOI：
10.1021/ja00903a021
复制
发表时间：
1963
影响因子：
15
通讯作者：
J. C. Martin
中科院分区：
文献类型：
--
作者：
R. Pearson;J. C. Martin
分子溴、n -溴丁二酰亚胺、n -溴四氟丁二酰亚胺和n -溴四甲基丁二酰亚胺在取代甲苯混合物的竞争性溴化中表现出相同的选择性。这一事实的解释，以链式机制涉及原子溴作为氢的抽象物种，与文献中的数据相一致，这些数据先前已被合理化的机制涉及琥珀酰基自由基在这一作用。自从n -溴代琥珀酰亚胺（NBS）发现并发展了烯丙基溴化和明显类似的苯基溴化反应以来，围绕这些反应的机理一直存在相当大的争议。大多数讨论都含蓄地假设这两种反应遵循相同的途径，尽管这方面的证据尚未得到证实。琥珀酰亚胺基自由基通常被认为是自由基链式反应中的链载体。3溴原子也被认为具有这种功能，最近也有证据
Molecular bromine, N-bromosuccinimide, N-bromotetrafluorosuccinimide, and N-bromotetramethylsuccinimide show identical selectivities in competitive brominations of mixtures of substituted toluenes. Inter-pretation of this fact in terms of a chain mechanism involving atomic bromine as the hydrogen abstracting species is reconciled with data in the literature which have previously been rationalized in terms of mechanisms involving succinimidyl radicals in this role.Since the discovery and development of allylic bromination, and theapparently analogous benzylic bromination, by N-bromosuccinimide1 2 (NBS), considerable controversy has centered about the mechanisms of these reactions. Most discussions have implicitly assumed that both reactions follow the same pathway, although proof of this has not yet been established. Succinimidyl radicals commonly have been assigned to the role of the chain-carrying species in a free radical chain reaction. 3 Bromine atoms have also been pro-posed as serving this function, 4 5and recently evidence