Structure–reactivity correlations in nucleophilic substitution reactions of Y-substituted phenyl X-substituted benzoates with anionic and neutral nucleophiles
作者:Ik-Hwan Um、Ji-Youn Lee、Mizue Fujio、Yuho Tsuno
DOI:10.1039/b607194e
日期:——
A kinetic study is reported for the reactions of 4-nitrophenyl X-substituted benzoates (1a-1) and Y-substituted phenyl benzoates (2a-1) with two anionic nucleophiles (OH(-) and CN(-)) and three amines (piperidine, hydrazine, and glycylglycine) in 80 mol% H(2)O-20 mol% dimethyl sulfoxide (DMSO) at 25.0 +/- 0.1 degrees C. Each Hammett plot exhibits two intersecting straight lines for the reactions of
动力学研究报道了4-硝基苯基X-取代的苯甲酸酯(1a-1)和Y-取代的苯基苯甲酸酯(2a-1)与两个阴离子亲核试剂(OH(-)和CN(-))和三种胺的反应(哌啶,肼和甘氨酰甘氨酸)在25.0 +/- 0.1摄氏度下于80 mol%H(2)O-20 mol%二甲基亚砜(DMSO)中的溶液。每个Hammett曲线对于1a-1反应显示两条相交的直线阴离子亲核试剂和哌啶,而相同反应的Yukawa-Tsuno图是线性的。2a-1与肼和甘氨酰甘氨酸反应的Hammett图显示,与sigma(-)常数的线性相关性比与sigma度或sigma常数的线性相关性好得多,这表明离去基团的离去发生在速率确定步骤(RDS)。相反,与相应的与OH(-)和CN(-)的反应相比,sigma(-)常数导致的Hammett相关性比sigma度常数差,这表明离去基团的离去发生在RDS之后与阴离子亲核试剂的反应。1a-1与阴离子亲核试剂反应获得的较大的rh(X)值(1