Complexes and Negative Activation Energies in Arylhalocarbene/Alkene Additions: Activation Parameter Dependence on Alkane Solvent Chain Length
作者:Lei Wang、Robert A. Moss、Karsten Krogh-Jespersen
DOI:10.1021/acs.joc.7b00186
日期:2017.4.21
Activation parameters for the additions of PhCCl, F5-PhCCl, and 3,5-dinitro-PhCCl to tetramethylethylene, cyclohexene, and 1-hexene have been determined in decane. With the exception of two carbene/alkene combinations, Arrhenius correlations of ln kaddn vs 1/T were unimodal and linear, affording negative activation energies and entropies. The additions of PhCCl or F5-PhCCl to 1-hexene gave bimodal
已在癸烷中确定了向四甲基乙烯,环己烯和1-己烯中添加PhCCl,F 5 -PhCCl和3,5-二硝基-PhCCl的活化参数。除了两种卡宾/烯烃组合以外,ln k addn与1 / T的阿伦尼乌斯相关性是单峰和线性的,提供了负的激活能和熵。PhCCl或F 5的添加对1-己烯的-PhCCl给出了双峰阿累尼乌斯相关性。与戊烷和计算研究中获得的类似实验数据进行比较有助于阐明观察到的行为。活化熵的降低与活化焓从戊烷到癸烷溶剂的降低同时发生,这表明在这些卡宾化合物中,焓-熵补偿是有效的。提出双峰Arrhenius行为是由于在癸烷溶剂笼组件中固有或外在地存在卡宾-烯烃而引起的。