Electronic Nature of Substituent X Governs Reaction Mechanism in Aminolysis of 4-Pyridyl X-Substituted-Benzoates in Acetonitrile
作者:Ik-Hwan Um、Ae Ri Bae
DOI:10.1021/jo300961y
日期:2012.7.6
through resonance interactions. The small ρX suggests that the k2/k–1 ratio is little influenced by the nature of substituent X. The Brønsted-type plots for aminolysis of 4-pyridyl 3,5-dinitrobenzoate 5a are linear with βnuc = 0.98 and 0.79 for k1k2/k–1 and k1k3/k–1, respectively. The effect of amine basicity on the microscopic rate constants is also discussed.
据报道,动力学研究了4-吡啶基X-取代的苯甲酸酯5a – i的氨解。对于在苯甲酰基部分(5a - d)中具有强吸电子基团的底物的反应,拟一级反应速率常数(k obsd)与[胺]的曲线向上弯曲,但对于那些带有苯并甲氧基的底物的反应则呈线性关系。给电子基团(5e – i),表明取代基X的电子性质决定了反应机理。所述ķ 1 ķ 2 / ķ -1和ķ 1 ķ 3 / ķ从k obsd / [胺]对[胺]的线性图的截距和斜率分别计算出–1值。哈米特情节为ķ 1 ķ 2 / ķ -1包含两个相交的直线,而汤川-津野情节表现出与ρ优异的线性相关X = 0.41和- [R = 1.58,这意味着非线性哈米特情节是不是由于速率确定步骤的改变,但是是由于具有通过共振相互作用而具有给电子基团的底物的稳定化引起的。小ρ X表明ķ 2 / ķ -1比率几乎不受取代基X的性质的影响。3,5-二硝基苯甲酸酯5a的4-吡啶基氨解的布朗斯台德图对于k