The kinetics of addition of a number of ortho-, meta-, and para-substituted benzylamines to β-nitrostyrene (NS) in acetonitrile have been studied. The reaction is first order with respect to NS. The order with respect to the amine is higher than one. It has been shown that the reaction follows two mechanistic pathways, uncatalyzed and catalyzed by the amine. The Arrhenius activation energy for the catalyzed path is negative, indicating the presence of a pre-equilibrium (k1, k−1) leading to the formation of a zwitterion. The values of the rate constant, k1, for the nucleophilic attack have been determined for 28 benzylamines. The rate constant k1 was subjected to correlation analysis using Charton's LDR and LDRS equations. The polar regression coefficients are negative, indicating the formation of a cationic species in the transition state. The reaction is subject to steric hindrance by ortho substituents. Key words: nucleophilic addition, benzylamines, correlation analysis, kinetics, alkene.
已添加的一系列邻-, 间-, 和对- 取代
苄胺对
乙腈中
β-硝基苯乙烯(NS)的动力学进行了研究。该反应对NS是一阶反应。对于胺而言,阶数大于一。已经表明该反应遵循两种机理途径,即未催化和由胺催化。胺催化途径的阿伦尼乌斯活化能为负值,表明存在一个预平衡(k1,k-1)导致偶离子的形成。28种
苄胺的亲核攻击速率常数k1已经确定。亲核攻击速率常数k1经过使用Charton的LDR和LDRS方程进行相关分析。极性回归系数为负值,表明在过渡态中形成了一个阳离子物种。该反应受邻位取代基的立体位阻影响。关键词:亲核加成,
苄胺,相关分析,动力学,烯烃。