Nucleophilic substitution reactions of diethyl 4-nitrophenyl phosphate triester: Kinetics and mechanism
作者:Enrique A. Castro、Daniela Ugarte、M. Fernanda Rojas、Paulina Pavez、José G. Santos
DOI:10.1002/kin.20605
日期:2011.12
Brønsted‐type plot (log kN vs. pKa nucleophile) obtained for the phenolysis is linear with slope β=0.21; no break was found at pKa 7.5, consistent with a concerted mechanism. The Brønsted‐type plots for the SA aminolysis and pyridinolysis are linear with slopes β=0.39 and 0.43, respectively, also suggesting concerted processes. The concerted mechanisms for the latter reactions are proposed on the basis
对4-乙基硝基苯基磷酸二乙酯(1)与一系列亲核试剂:酚盐,脂环族仲胺(SA)和吡啶的反应进行了动力学研究。在亲核试剂过量的情况下,所有反应都遵循伪一级动力学,并且在亲核试剂中都是一级反应。对于所研究的所有反应,所获得的亲核速率常数(k N)均与pH无关。酚醛化得到的布朗斯台德图(log k N vs. p K a亲核试剂)是线性的,斜率β= 0.21。在p K a处未发现中断7.5,符合协调机制。SA氨解和吡啶分解的布朗斯台德图是线性的,斜率分别为β= 0.39和0.43,也表明过程是一致的。提出后一种反应的协调机制是基于在Brønsted型图中没有中断,以及在这些反应中形成的假设五元中间体的不稳定性。©2011 Wiley Periodicals,Inc.国际化学杂志Kinet 43:708–714,2011