杀虫剂 Fenitrothion 对 O 和 N 亲核试剂的反应性。

Reactivity of the insecticide fenitrothion toward O and N nucleophiles.

机构信息

Instituto de Investigaciones en Fisicoquímica de Cordoba (INFIQC), Departamento de Química Orgánica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Medina Allende y Haya de la Torre, Argentina.

出版信息

J Org Chem. 2010 May 21;75(10):3427-36. doi: 10.1021/jo100541y.

DOI:10.1021/jo100541y

PMID:20423065

Abstract

The reactivity of Fenitrothion (1) toward several O- and N-based nucleophiles, including ambident and alpha-nucleophiles, was investigated in basic media at 25 degrees C in water containing 2% 1,4-dioxane. In the reactions with HO(-) and HOO(-) quantitative formation of 3-methyl-4-nitrophenoxide (2) was observed indicating a S(N)2(P) pathway. In the reactions with NH(2)OH, NH(2)O(-), and BuNH(2), demethylfenitrothion (4) was formed along with 2, indicating competition between the S(N)2(P) and S(N)2(C) pathways; no evidence of a S(N)Ar pathway was observed in any case. The observed rate constants were dissected into the values corresponding to the S(N)2(P) and S(N)2(C) pathways. The yield of 4 depends on the nucleophile and on the pH of the reaction, being the main product in the case of BuNH(2). With HOO(-), NH(2)OH, and NH(2)O(-) a significant alpha-effect was observed, confirming the participation of the nucleophile in the rate-limiting step of the reaction.

摘要

在 25°C 的水中，含有 2% 1,4-二恶烷的碱性介质中，研究了 Fenitrothion（1）与几种 O-和 N-亲核试剂的反应性，包括 ambident 和 alpha-亲核试剂。在与 HO(-) 和 HOO(-) 的反应中，观察到定量形成 3-甲基-4-硝基苯酚盐（2），表明存在 S(N)2(P)途径。在与 NH(2)OH、NH(2)O(-) 和 BuNH(2)的反应中，除了 2 之外，还形成了 demethylfenitrothion（4），表明 S(N)2(P)和 S(N)2(C)途径之间存在竞争；在任何情况下都没有观察到 S(N)Ar 途径的证据。观察到的速率常数被分解为对应于 S(N)2(P)和 S(N)2(C)途径的值。4 的产率取决于亲核试剂和反应的 pH 值，在 BuNH(2)的情况下是主要产物。对于 HOO(-)、NH(2)OH 和 NH(2)O(-)，观察到显著的 alpha-效应，证实了亲核试剂参与反应的限速步骤。