Kinetic Support for the Generation of a Phenylsulfenium Ion Intermediate

Molecules

Hiroshi Takeuchi¹  Jun-ichi Tateiwa¹ 

[1] Department of Chemical Science and Engineering, Faculty of Engineering, Kobe University, Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan

关键词: Phenylsulfenium ion intermediate;    Kinetic study;    Phenylthiolation;    Sulfenamide;    Thioanisole;   

DOI  :  10.3390/80400392

来源: mdpi

【 摘 要 】

In the reaction of N-methylbenzenesulfenamide (1) with thioanisole (4) in the presence of trifluoroacetic acid (TFA), the initial rate υ0 of total appearance of 2- and 4-(methylthio)phenyl phenyl sulfides (5) is first and zero order with respect to the initial concentrations of 1 and 4, respectively: υ₀=k_obs[1]₀. The pseudo-first order rate constant kobs is evaluated as 5.2×10^-4 sec^-1 with varying concentrations of 4 (0.72 to 5.0 M) in a mixture of 4 and CH₂Cl₂ in the presence of TFA at 10 °C. This data supports the notion that a phenylsulfenium ion intermediate 3 interacting with both the counter ion and the unshared electron-pair of amine is generated by heterolytic N-S scission of the protonated sulfenamide 2, leading to the observed formation of 5.

【 授权许可】

CC BY   
This is an open access article distributed under the Creative Commons Attribution License (CC BY) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.