We present a kinetic and theoretical study of electrophilic aromatic substitution (S_EAr) involving 2-(2′,4′,6′-trinitrophenyl)-4,6-dinitrobenzotriazole 1-oxide 1 with a series of 5-R-substituted indoles 2a-e (R = CN, Cl, H, Me and NH₂) in acetonitrile at 20 °C. Single electron transfer (SET) mechanism was proposed and confirmed by the agreement between the rate constants (k) and the oxidation potentials (E_p^ox) of these series of indoles. Using Mayr's equation, the electrophilicity parameter (E) of 1 at C-7 position is derived and compared with the same parameter estimated using empirical equation E versus. pK_a. Density Functional Theory (DFT) calculations were performed to confirm the suggested reaction mechanisms and elucidate the origin of the electrophilic reactivity of 1. Notably, a linear correlation (R² = 0.9957) between the experimental nucleophilicity (N) and the theoretical model of nucleophilicity (ω⁻¹) determined in this work of various 5-R-substituted indoles has been obtained and discussed.

Graphical abstract

Mayr and Parr's approaches were combined with the correlation N vs ω⁻¹ established in the present work, to evaluate the empirical electrophilicity parameter (E) of 2-(2′,4′,6′-trinitrophenyl)-4,6-dinitrobenzotriazole 1-oxide and the unknown nucleophile specific parameters (N and s_N) of four new 5-R-substituted indoles (R = NO₂, F, H and N(CH₃)₂) in acetonitrile.

中文翻译：

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结合动力学和理论方法研究 2-(2′,4′,6′-三硝基苯基)-4,6-二硝基苯并三唑 1-氧化物与 5-R-取代吲哚在乙腈中的 SEAr 反应

我们提出了涉及 2-(2′,4′,6′-三硝基苯基)-4,6-二硝基苯并三唑 1-氧化物1与一系列 5-R-取代的亲电芳族取代 (S _E Ar)的动力学和理论研究吲哚2a-e（R = CN、Cl、H、Me 和 NH ₂）在乙腈中，20 °C。单电子转移（SET）机制被提出并通过这一系列吲哚的速率常数（k）和氧化电位（E _p ^ox ）之间的一致性得到证实。使用 Mayr 方程，推导了1在 C-7 位置的亲电性参数 ( E ) ，并与使用经验方程E vs估计的相同参数进行比较。 pK _a。进行密度泛函理论 (DFT) 计算以确认所建议的反应机制并阐明1亲电子反应性的起源。值得注意的是，我们获得并讨论了各种 5-R 取代吲哚的实验亲核性 ( N ) 与理论亲核性模型 (ω ^-1 ) 之间的线性相关性 (R ²  = 0.9957) 。

图形概要

Mayr和Parr的方法与本工作中建立的N与ω ^{-1 的}相关性相结合，评估了2-(2′,4′,6′-三硝基苯基)-4,6-二硝基苯并三唑的经验亲电参数( E)乙腈中四种新的 5-R-取代吲哚（R = NO ₂、F、H 和 N(CH ₃ ) ₂ ）的1-氧化物和未知亲核试剂特定参数（N和s _{N ）。}