Structure-Reactivity Correlations in Nucleophilic Displacement Reactions of Y-Substituted-Phenyl X-Substituted-Cinnamates with Z-Substituted-Phenoxides
作者:Yu-Jin Son、Eun-Hee Kim、Ji-Sun Kang、Ik-Hwan Um
DOI:10.5012/bkcs.2013.34.8.2455
日期:2013.8.20
linear correlation with ρX = 0.89 and r = 0.58. The Bronsted-type plot for the reactions of 4-nitrophenyl cinnamate (4c) with Z-substituted-phenoxides is linear with βnuc = 0.76. The Bronsted-type plot for the reactions of Y-substituted-phenyl cinnamates (5a-5d) with 4-chlorophenoxides (4ClPhO – ) is also linear with βlg = –0.72. The Hammett plot correlated with σ – constants for the reactions of 5a5d
已经通过分光光度法测量了 4-硝基苯基 X-取代肉桂酸酯 (4a-4e) 和 Y-取代苯基肉桂酸酯 (5a-5e) 与 Z-取代苯氧基阴离子的亲核置换反应的二级速率常数 (kN)在 80 mol % H2O/20 mol % DMSO 中,温度为 25.0 ± 0.1 o C。 4a-4e 与 4-氯酚 (4-ClPhO – ) 反应的 Hammett 图由两条相交的直线组成,可将其视为速率决定步骤 (RDS) 的变化。然而,已经得出结论,非线性哈米特图不是由于 RDS 的变化,而是由于通过共振相互作用在肉桂酰基部分具有吸电子基团的底物的基态稳定引起的,因为 Yukawa-Tsuno图与 ρX = 0.89 和 r = 0.58 表现出极好的线性相关性。肉桂酸 4-硝基苯酯 (4c) 与 Z-取代的酚盐反应的布朗斯台德型图是线性的,βnuc = 0.76。Y-取代的肉桂酸苯酯 (5a-5d)