Kinetic Study on Nucleophilic Substitution Reactions of 4-Nitrophenyl X-Substituted- 2-Methylbenzoates with Cyclic Secondary Amines in Acetonitrile: Reaction Mechanism and Failure of Reactivity-Selectivity Principle

Bulletin of the Korean chemical society

Min-Young Kim¹  Ik-Hwan Um¹  Ji-Youn Lee¹ 

关键词: Aminolysis;    Reaction mechanism;    Hammett plot;    Yukawa-Tsuno plot;    Brønsted-type plot;   

DOI  :  

学科分类：化学（综合）

来源: Korean Chemical Society

【 摘 要 】

A kinetic study is reported on nucleophilic substitution reactions of 4-nitrophenyl X-substituted-2-methylbenzoates (5a-e) with a series of cyclic secondary amines in MeCN at 25.0 ± 0.1 oC. The Hammett plots for the aminolysis of 5a-e are nonlinear, e.g., substrates possessing an electron-donating group (EDG) in the benzoyl moiety deviate negatively from the linear line composed of substrates bearing no EDG. In contrast, the Yukawa-Tsuno plots for the same reactions exhibit excellent linear correlations with X = 0.30-0.59 and r = 0.90-1.15, indicating that the nonlinear Hammett plots are caused by stabilization of the substrates possessing an EDG through resonance interactions but are not due to a change in the rate-determining step (RDS). The Brønsted-type plots are linear with nuc = 0.66-0.82. Thus, the aminolysis of 5a-e has been suggested to proceed through a stepwise mechanism in which departure of the leaving group occurs at the RDS. The X and nuc values for the aminolysis of 5a-e increase as the reactivity of the substrates and amines increases, indicating that the reactivity-selectivity principle is not applicable to the current reactions.

【 授权许可】

Unknown