Effects of mixed H2O?CH3CN solvents on the Br�nsted coefficient for the intramolecular general base-catalyzed cleavage of ionized phenyl salicylate in the presence of primary and secondary amines
作者:M. Niyaz Khan、Z. Arifin、A. George、I. A. Wahab
DOI:10.1002/(sici)1097-4601(2000)32:3<153::aid-kin5>3.0.co;2-w
日期:——
Nucleophilic second-order rate constants, knms, for the reactions of several primary and secondary amines with ionized phenyl salicylate (PS−) show a nonlinear decrease with the increase in the content of CH3CN from 2 to ≤50% v/v in mixed aqueous solvent. The values of knms remain almost unchanged with the change in the content of CH3CN at >50% v/v. The nucleophilic reactivity of primary and secondary
几种伯胺和仲胺与离子化水杨酸苯酯 (PS-) 反应的亲核二级速率常数 knms 随着 CH3CN 含量从 2 增加到 ≤50% v/v 在混合水溶液中呈现非线性下降溶剂。随着 CH3CN 含量的变化 > 50% v/v,knms 值几乎保持不变。伯胺和仲胺对 PS− 的亲核反应性揭示了混合水溶剂中 CH3CN 含量恒定时不同布朗斯台德系数 βnuc 的布朗斯台德图。随着 CH3CN 含量从 2% 增加到 70% v/v,βnuc 的值对于伯胺从 0.4 降低到接近 0,对于仲胺从 0.22 降低到 0.12。在 2–50%v/v CH3CN 范围内获得的 knms/kMeOHms 值(其中 kMeOHms 表示 MeOH 与 PS- 在 H2OCH3CN 溶剂中反应的亲核二级速率常数)符合经验方程:log (knms /kMeOHms) = θ + λX 其中 X 是 CH3CN 的 % v/v