Gas-Phase Substituent Effects in Highly Electron-Deficient Systems. II. Stabilities of 1-Aryl-2,2,2-trifluoroethyl Cations Based on Chloride-Transfer Equilibria
作者:Masaaki Mishima、Hiroki Inoue、Mizue Fujio、Yuho Tsuno
DOI:10.1246/bcsj.70.1163
日期:1997.5
of −10.6, supporting our previous conclusion that the highly electron-deficient benzylic carbocation systems are characterized by extremely high resonance demands. This r+ value, furthermore, conformed a linear relationship between the r+ value and the relative stability of the unsubstituted member of the respective benzylic carbocations, clearly demonstrating a continuous spectrum of varying resonance
1-芳基-2,2,2-三氟乙基阳离子的相对稳定性是根据气相中的氯离子转移平衡确定的。Yukawa-Tsuno 方程对平衡常数的这种取代基效应的应用给出了 1.53 的显着更大的 r+ 和 -10.6 的 ρ,支持我们先前的结论,即高度缺电子的苄型碳正离子系统的特征在于极高的共振需求. 此外,该 r+ 值符合 r+ 值与相应苄型碳正离子的未取代成员的相对稳定性之间的线性关系,清楚地证明了碳正离子稳定性特征的变化共振需求的连续谱。正电荷的 π-离域进入芳基 π-系统随着连接到中心碳的 α-取代基对碳正离子的去稳定作用而增加。此外,发现 1-芳基-2,2,2-三氟乙基阳离子的 r+ 值为 1.53...