Bulletin of the Korean Chemical Society | |
Kinetic Study on Aminolysis of 4‐Pyridyl Benzoate and O‐4‐Pyridyl Thionobenzoate in Acetonitrile: Factors Influencing Reactivity and Reaction Mechanism | |
In Lee1  Young Kim2  Hwan Um2  Min‐3  Ik‐3  Jae‐4  | |
[1] 714 Korea;750 Korea;Department of Chemistry and Nano Science Ewha Womans University Seoul 120‐Department of Chemistry and Plant Resources Research Institute Duksung Women's University Seoul 132‐ | |
关键词: Aminolysis; O‐; 4‐; Pyridyl thionobenzoate; Catalyzed reaction; Brø; nsted plot; Concerted mechanism; | |
DOI : 10.1002/bkcs.10906 | |
学科分类:化学(综合) | |
来源: Korean Chemical Society | |
【 摘 要 】
A kinetic study on nucleophilic substitution reactions of 4âpyridyl benzoate (2a) and Oâ4âpyridyl thionobenzoate (2b) with a series of cyclic secondary amines in acetonitrile at 25.0°C is reported. Plots of pseudoâfirstâorder rate constant (kobsd) vs. [amine] are linear and pass through the origin for the reactions of 2a but curve upward for those of 2b. The upward curvature observed for the reactions of 2b is typical for reactions that proceed through a stepwise mechanism with a zwitterionic intermediate T±, which decomposes to the products via uncatalyzed and catalyzed routes competitively. The reaction of 2a has been suggested to proceed through a stepwise mechanism with T±, in which expulsion of the leaving group occurs in the rateâdetermining step on the basis of a linear Brønstedâtype plot with βnuc = 0.77. The catalyzed reaction of 2b from T± has been proposed to proceed through a concerted mechanism with a sixâmembered cyclic transition state rather than via a stepwise pathway with an anionic intermediate Tâ. Factors influencing reactivity and reaction mechanism are discussed in detail.
【 授权许可】
Unknown
【 预 览 】
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RO201904035672440ZK.pdf | 62KB | download |