Kinetic and equilibrium studies of σ-adduct formation and nucleophilic substitution in the reactions of 2-chloro-3,5-dinitropyridine and 2-ethoxy-3,5-dinitropyridine with p-substituted anilines in DMSO
作者:Basim H. Asghar
DOI:10.1007/s00706-012-0860-z
日期:2013.3
5-dinitropyridine with a series of p-substituted anilines in the presence of 1,4-diazabicyclo[2.2.2]octane (DABCO) were studied in DMSO. The reactions yielded 2-anilino-3,5-dinitropyridine derivatives, and no accumulation of intermediates could be detected spectrophotometrically. The rates were compatible with a two-step mechanism involving initial nucleophilic attack followed by either base-catalysed or
摘要在1,4-二氮杂双环[2.2.2]辛烷存在下2-氯-3,5-二硝基吡啶和2-乙氧基-3,5-二硝基吡啶与一系列对位取代苯胺反应的速率和平衡结果(DABCO)在DMSO中进行了研究。反应产生2-苯胺基-3,5-二硝基吡啶衍生物,并且分光光度法未检测到中间体的积累。该速率与两步机制兼容,该机制涉及最初的亲核攻击,然后是碱催化的或未催化的转化为产物。碱催化的途径可能涉及限速质子从两性离子中间体到碱的转移,以产生阴离子σ-加合物。对数p的log K 1 k DABCO的图K a值在25°C时具有良好的直线,2-氯-和0.4-5-(2-乙氧基-3,5-二硝基吡啶)的斜率。将结果与2-苯氧基-3,5-二硝基吡啶与取代苯胺的反应结果进行了比较。 图形概要