Reactions in strongly basic media. Part 9. Correlation of the rates of methoxide-catalysed methanolysis of 1-substituted 2,4-dinitrobenzenes and 2-substituted 5-nitropyridines in methanolic dimethyl sulphoxide with an acidity function. Details of the mechanistic pathway
作者:Keith Bowden、Nighat S. Nadvi
DOI:10.1039/p29870000189
日期:——
measured in methanolic DMSO at 20.0 or 21.0 °C. For the 2-substituted 5-nitropyridines and for the 1-substituted 2,4-dinitrobenzenes below ca. 55 mol% DMSO, the rates have been correlated with an acidity function of the medium. The slopes of these linear relations are discussed. The 1-substituted 2,4-dinitrobenzenes above ca. 55 mol% DMSO give rise to Meisenheimer complexes as intermediates and/or as the
在甲醇DMSO中,在20.0或21.0°C下,测量了一系列1-取代的2,4-二硝基苯和2-取代的5-硝基吡啶的甲醇盐催化的甲醇分解的速率系数。对于2-取代的5-硝基吡啶和对于低于ca的1-取代的2,4-二硝基苯。55 mol%DMSO,速率与介质的酸度函数相关。讨论了这些线性关系的斜率。高于ca的1-取代的2,4-二硝基苯。55mol%的DMSO产生Meisenheimer络合物作为中间体和/或反应产物。然后,反应产物变为甲醇盐和2,4-二硝基苯甲醚的1,1-Meisenheimer络合物。对于1-氟底物,后者的形成决定了速率。对于其他1个取代的底物,1,3-Meisenheimer配合物的分解将决定速率。