Kinetics and Mechanistic Study of the Reaction of Cyclic Anhydrides with Substituted Phenols. Structure−Reactivity Relationships
作者:Gabriel O. Andrés、Rita H. de Rossi
DOI:10.1021/jo048183l
日期:2005.2.1
maleic anhydrides with different substituted phenols (Z-PhOH with Z = H, m-CH3, p-CH3, m-Cl, p-Cl, and m-CN) were studied in aqueous solution. Two kinetic processes well separated in time were observed. The fast one is attributed to the formation of the aryl ester in equilibrium with the anhydride and allows the determination of the rate of nucleophilic attack of the phenol on the anhydride (k-A).
研究了邻苯二甲酸和马来酸酐与不同取代酚(Z = PhOH,Z = H,m -CH 3,p -CH 3,p -CH 3,m -Cl,p -Cl和m -CN)反应的动力学。解决方案。观察到时间上充分分开的两个动力学过程。最快的是归因于与酸酐形成平衡的芳基酯的形成,并可以确定苯酚对酸酐的亲核进攻速率(k - A)。从慢动力学过程中,确定该反应的平衡常数。取代酚对酸酐的亲核攻击的布朗斯台德图呈线性,邻苯二甲酸和马来酸酐的斜率βNuc分别为0.45和0.56。结果与涉及速率决定亲核攻击的机制以及一致的机制是一致的。计算出的参与反应的原子的有效电荷和布朗斯台德β值与涉及协同或强制协同机制的机理一致,在该机理中,沿反应坐标未形成具有显着寿命的四面体中间体。与逐步过程相比,后一种机制更为可取。