Investigation of electronic effects in the pyridine and pyridine N-oxide rings. Part 4. Kinetics and mechanism of the reaction of diazodiphenylmethane with substituted carboxypyridine and 2-carboxypyridine N-oxides in dimethylformamide
作者:Mirjana Radojković-Veličković、Milica Mišić-Vuković
DOI:10.1039/p29840001975
日期:——
Rate constants for the reactions of 15 substituted carboxypyridines and four substituted 2-carboxy-pyridine N-oxides with diazodiphenylmethane (DDM) in dimethylformamide (DMF) were determined at 30 °C, by the known spectrophotometric method. For comparison, rate constants for the reaction of 12 substituted benzoic acids were determined under the same conditions. Kinetic and thermodynamic parameters
通过已知的分光光度法,在30°C下测定15个取代的羧基吡啶和四个取代的2-羧基吡啶N-氧化物与重氮二苯基甲烷(DDM)在二甲基甲酰胺(DMF)中的反应的速率常数。为了比较,在相同条件下确定12种取代的苯甲酸反应的速率常数。所获得的动力学和热力学参数,连同产物分析,基本上验证了先前提出的在该溶剂中的反应机理。对结果进行了经验性的Hammett处理,结果表明,散布的总体图(ρ= 1.019,log k o = –2.98,r = 0.91,s = 0.22,n从吡啶氮杂基团和N-氧化物基团的相应σ值以及取代基的Hammettσ常数中,通过加法σ常数获得= = 31)。从取代的苯甲酸(ρ= 1.213,log k o = –2.91,r = 0.985,s = 0.12,n = 12),卤素和硝基取代酸(ρ= 1.07, log k o = –2.99,r = 0.998,s = 0.02,n =