<i>N</i>-(Hydroxybenzyl)benzamide Derivatives: Aqueous pH-Dependent Kinetics and Mechanistic Implications for the Aqueous Reactivity of Carbinolamides
作者:Takaoki Koyanagi、Paul M. Siena、David E. Przybyla、Mohammad I. Rafie、Richard W. Nagorski
DOI:10.1021/acs.joc.9b02812
日期:2020.1.17
derivatives were found to react via three distinct mechanisms with the kinetically dominant mechanism being dependent on the pH of the reaction solution. It has been shown that the carbinolamides react via a specific-base-catalyzed mechanism (E1cB-like) under basic and pH neutral conditions. At lower pH values, an acid-catalyzed mechanism was kinetically dominant and, last, a water reaction was postulated
对于一系列酰胺取代的N-(羟基苄基)苯甲酰胺衍生物,在25°C H2O中,I = 1.0 M(KCl)的条件下,确定了pH在0至14之间的水反应速率常数。发现N-(羟基苄基)苯甲酰胺衍生物通过三种不同的机理反应,其中动力学主导机理取决于反应溶液的pH。已经表明,羧酰胺在碱性和pH中性条件下通过特定的碱催化机理(E1cB-like)反应。在较低的pH值下,酸催化的机理在动力学上占主导地位,最后,假定在pH值下水反应既不依赖氢氧化物也不是一般酸催化机理占主导地位。与之前对N-(羟甲基)苯甲酰胺化合物的研究相反,对于在0至14的pH值之间研究的任何N-(羟基苄基)苯甲酰胺衍生物,均未观察到基于酰胺取代基性质的机械变化的证据。酸催化反应的速率(kH,ρ= -1.17),表观二级氢氧化物速率常数(k1',ρ= 0.87),非氢氧化物依赖性速率(k1,ρ= 0.65)和pKa's报道了羧甲酰胺的羟基含量(ρ=