已经合成了具有和不具有侧翼甲基的一系列对-环丙基苯基tropyliumium离子以及作为参考化合物的各种甲基取代的苯基tropyliumium离子。通过1 H nmr光谱,p K R +测量以及铬(II)离子对单电子还原的速率测量,研究了对环丙基对阳离子稳定性的构象效应。检查1 H nmr光谱和这些阳离子的p K R +值表明,由于电荷离域到对位体而产生的稳定作用-环丙基随着侧翼甲基的引入而减少。当绘制铬(II)离子还原的log k 2与未取代的m-和p-甲基-,m,m-二甲基-和m-和p-甲基-的取代基常数σ +的总和时,观察到线性自由能关系。p -环丙基- phenyltropylium离子,但登录ķ 2为p具有一个或两个侧翼甲基的β-环丙基取代的阳离子大大偏离线性相关线,反映出由于环丙基的构象变化而导致的稳定性损失。
Partial rate factors for the nitration of cyclopropylbenzene derivatives. Influence of geometry on the stability of 3- and 4-cyclopropylbenzenonium ions
Partial rate factors for the nitration of cyclopropylbenzene derivatives. Influence of geometry on the stability of 3- and 4-cyclopropylbenzenonium ions
作者:Leon M. Stock、Paul E. Young
DOI:10.1021/ja00767a036
日期:1972.6
The one-electron reduction of carbonium ions. Part 12. The conformational effect of the para-cyclopropyl group on the stability of phenyltropylium ions and on their reducibilities with chromium(II) ion
p-cyclopropylphenyltropylium ions with and without flanking methyl groups has been synthesized together with various methyl-substituted phenyltropylium ions as reference compounds. The conformational effect of the para-cyclopropyl group upon the cation stability has been studied by means of 1H n.m.r. spectroscopy, pKR+ measurements, and rate measurements of one-electron reduction with chromium(II) ion. Examination
已经合成了具有和不具有侧翼甲基的一系列对-环丙基苯基tropyliumium离子以及作为参考化合物的各种甲基取代的苯基tropyliumium离子。通过1 H nmr光谱,p K R +测量以及铬(II)离子对单电子还原的速率测量,研究了对环丙基对阳离子稳定性的构象效应。检查1 H nmr光谱和这些阳离子的p K R +值表明,由于电荷离域到对位体而产生的稳定作用-环丙基随着侧翼甲基的引入而减少。当绘制铬(II)离子还原的log k 2与未取代的m-和p-甲基-,m,m-二甲基-和m-和p-甲基-的取代基常数σ +的总和时,观察到线性自由能关系。p -环丙基- phenyltropylium离子,但登录ķ 2为p具有一个或两个侧翼甲基的β-环丙基取代的阳离子大大偏离线性相关线,反映出由于环丙基的构象变化而导致的稳定性损失。
Structural effects in solvolytic reactions. 16. The effect of conformation of the cyclopropyl, phenyl, and isopropyl substituents on their electronic contributions to the electron-deficient center