respectively. The predicted breaks of the Brönsted plots for stepwise mechanisms are pK(a)0 = 6.8 and 7.3, respectively. The lack of Brönsted breaks for these reactions and the values of the Brönsted slopes are consistent with concerted mechanisms. By comparison of the reactions under investigation among them and with similar aminolysis and pyridinolysis, the following conclusions can be drawn: (i) Secondary
仲脂环族胺与2,4,6-三硝基
苯基碳酸甲酯(
TNPMC)和2,4,6-三
硝基苯基
乙酸甲酯(
TNPA)的反应在25.0摄氏度的
水溶液中进行动力学研究,离子强度为0.2(KCl )。通过分光光度法(360 nm)释放2,4,6-三
硝基苯氧根阴离子来研究反应。在胺过量下,发现伪一阶速率系数(k(obsd))。k(obsd)对[胺]的图是线性的,其斜率(kN)与pH无关。布朗斯台德型图(胺的共轭酸的log k(N)vs pK(a))是线性的,
TNPA和
TNPMC的反应斜率分别为β= 0.41和β= 0.36。逐步机理的布朗斯台德图的预测断裂分别为pK(a)0 = 6.8和7.3。这些反应缺乏布朗斯泰特断裂,布朗斯泰德斜率的值与协调机制一致。通过比较所研究的反应以及类似的
氨解和
吡啶分解反应,可以得出以下结论:(i)脂环族仲胺通过协同机制与
TNPA和
TNPMC反应。(ii)由于MeO从后者的底物中释放