Factors influencing the condensation of 4-aminoantipyrine with derivatives of hydroxybenzene—II. Influence of hydronium ion concentration on absorptivity
Factors influencing the condensation of 4-aminoantipyrine with derivatives of hydroxybenzene—II. Influence of hydronium ion concentration on absorptivity
复制标题
影响4-氨基安替比林与羟基苯衍生物缩合的因素—II.水合氢离子浓度对吸收率的影响
DOI：
10.1016/0043-1354(67)90027-9
复制
发表时间：
1967
期刊：
影响因子：
12.8
通讯作者：
Edward W. Mikulewicz
中科院分区：
文献类型：
--
作者：
S. Faust;Edward W. Mikulewicz
在pH值为8.0和10.0的条件下，研究了4-氨基安替比林与几种苯的羟基衍生物的氧化偶联反应。提出了反应机理。看来，4-氨基安替比林对苯酚的帕拉施加亲电攻击。[H3+O]以两种方式影响这种攻击：（a）在pH 8.0下观察到更大的反应性，因为苯酚表现出更大的解离为酚氧离子。这归因于由−0−的较强电子释放性质提供的更有利的反应动力学，以及（B）在pH 10.0下观察到较小的反应性，这归因于4-氨基安替比林的亲电特性的降低。苯环上的帕拉取代对反应有两种影响：（a）CH_3-、C_2 H_5-、C_6 H_5-等取代基明显阻断氧化偶联反应;（B）Cl-、Br-、NH_2-、CH_3-、C_2 H_5 O-等取代基改变氧化偶联反应。后者可能是由于亲电取代和取代基的迁移或偶氮型结构的形成。本文提供的数据非常强烈地显示了4-氨基安替比林用于测定水和废水中酚类的分析应用的局限性。通过在动力学更有利的pH值8.0下进行反应可以获得一些优点。
The oxidative coupling of 4-aminoantipyrine with several hydroxy derivatives of benzene has been examined at pH values of 8.0 and 10.0. A reaction mechanism has been proposed. It appears that 4-aminoantipyrine exerts an electrophilic attack upon the para position of the phenol. [H3+O] influences this attack in two ways: (a) greater reactivity is observed at pH 8.0 as the phenol exhibits greater dissociation to a phenoxide ion. This is ascribed to more favorable reaction kinetics offered by the stronger electron-releasing properties of the −0−, and (b) lesser reactivity is observed at pH 10.0 that is ascribed to a reduction of the electrophilic characteristics of the 4-aminoantipyrine. Substitution in the para position of the benzene ring influences the reaction in two ways: (a) oxidative coupling is blocked apparently by such substituents as CH3-, C2H5-, C6H5-, and (b) oxidative coupling is altered by such substituents as Cl-, Br-, NH2-, CH3-, and C2H5O-. The latter may be due to electrophilic displacement and migration of the substituent or to formation of azo-type structures.The data offered herein very strongly shows the limitations of the analytical application of 4-aminoantipyrine for determination of phenols in water and waste water. Some advantage may be gained by conducting the reaction at a pH value of 8.0 where kinetics are more favorable.