Kinetic Investigation of the Reactions of <i>S</i>-4-Nitrophenyl 4-Substituted Thiobenzoates with Secondary Alicyclic Amines in Aqueous Ethanol
作者:Enrique A. Castro、Jorge Bessolo、Raul Aguayo、José G. Santos
DOI:10.1021/jo0348120
日期:2003.10.1
an increasing nucleofugality of SAA from T(+/-). The greater pK(a)(0) value for the reactions of SAA with 1, relative to that found in the pyridinolysis of 2,4-dinitrophenyl benzoate (pK(a)(0) = 9.5), is explained by the greater nucleofugality from T(+/-) of the former amines, compared to isobasic pyridines, and the greater leaving ability from T(+/-) of 2,4-dinitrophenoxide relative to 4-nitrobenzenethiolate
将S-4-硝基苯基4-X-取代的硫代苯甲酸酯(分别为X = H,Cl和NO(2):1、2和3)与一系列仲脂环族胺(SAA)的反应进行在25.0摄氏度和0.2 M(KCl)的离子强度下,在44 wt%的乙醇-水中进行动力学研究。通过分光光度法通过监测在420-425nm下4-硝基苯硫醇根阴离子的释放来跟踪反应。在过量的胺下,对于所有反应均获得伪一级反应速率常数(k(obsd))。在恒定pH值下k(obsd)与[SAA]的曲线与斜率(k(N))呈线性关系,而与pH无关。经统计学校正的1和2反应的布朗斯台德型图(log k(N)/ q vs pK(a)+ log p / q)是非线性的,斜率在高pK(a)时,beta(1)= 0.27分别为0.10和0.10,并且在低pK(a),β(2)分别为0.86和0.84时的斜率。布朗斯台德曲率分别位于pK(a)(pK(a)(0))10.0和10.4的中心。SAA与3的反应显示斜率为0