Electron transfer induced isomerization of cis-4,4'-diphenylstilbene into its trans form
作者:C. K. Chien、H. C. Wang、M. Szwarc、A. J. Bard、K. Itaya
DOI:10.1021/ja00529a036
日期:1980.4
spontaneous isomerization to the respective radical anion or dianion of trans-stilbene. Electron transfer from the latter to the unreduced cis-stilbene generates the original cis radical anions or dianions and continues the process. Spontaneous isomerization of cis-stilbene radical anions, or their ion pairs, is slow, whereas the dianions, or their aggregates with cations, isomerize rapidly. Which of these
4,4'-二苯基芪,顺式和反式异构体用C和T表示,还有T-。和 T2-, 进行了光谱和电化学表征。歧化2T-.,Na+F!T + T2-,2Na+ 在 THF 0.04、AH = 18.2 kcal/mol 和 AS = 54 cal/mol-deg 中具有平衡常数,其速率常数为 9.0 X lo8 MI sl。在环境温度下,在 THF 中研究顺反异构化的三个系统:T + T-.,Na+ C, T2-,2Na+ + C 和 B-.,Na+ + C, B 表示联苯。在前两个系统中,反应受三个相互关联的平衡控制,即 C + T-.,Na+ s T + C-.,Na+ (Kl), C + T2-,2Na+ s C-.,Na+ + T -.,Na+, (K2 = Kl/Kdispr) 和 2T-.,Na+ F!T + T2-,2Na+ (Kdispr),速率决定步骤为 C-.,Na+ T-.,Na+