碱性介质中对硝基芳氧酸的稳定性研究  

THE STABILITY OF p-NITRO ARYLOXY CARBOXYLIC ACID IN THE ALKALINE MEDIUM

作　　者：刘巧云[1] 席海涛[2] 孙小强[2] 

机构地区：[1]常州工程职业技术学院应用化学系,江苏常州213004 [2]江苏工业学院,江苏常州213016

出　　处：《石油化工高等学校学报》2004年第3期48-51,共4页Journal of Petrochemical Universities

基　　金：国家自然科学基金资助课题 (2 0 2 72 0 19)

摘　　要：设计合成了 3种含吸电子基—NO2 的芳氧酸 :对硝基苯氧乙酸、对硝基苯氧丙酸、对硝基苯氧丁酸 ,并以其作为研究对象 ,对碱性介质中芳醚键的稳定性进行了研究。选用对硝基甲苯为内标 ,用高效液相色谱仪对芳氧酸的醚键断裂程度进行了分析 ,并用内标法计算出它们的转化率。分别绘制了取代产物———对硝基苯乙醚和对硝基苯酚的校正曲线 ,并对二者的摩尔浓度比进行了定量分析。结果表明 ,由于—NO2 的存在 ,对硝基芳氧酸在碱性溶液中易发生亲核取代反应 ,使醚键断裂 ,从而使这类化合物出现不稳定性。发现对硝基苯氧丙酸亲核取代的异常情况 ,其醚键断裂的程度最大 ,并且取代产物反常 ,推测可能是发生了分子内邻基参与的亲核取代反应。Three kinds of aryloxy carboxylic acid containing strong electron-withdrawing group(—NO_2)were synthesized and used to study the stability of aryl etherbond in the alkaline medium,which were p-nitrophenoxy acetic acid、p-nitrophenoxy propionic acid、p-nitrophenoxy butyric acid.p-nitrotoluene had been taken as the internal standard,extent of etherbond cleavage had been analyzed by high performance liquid chromatographic instrument,the conversion of aryloxy carboxylic acid was calculated by means of internal standard method.Calibration curves of p-nitrophenetole and p-nitrophenol ,which were substituted products,were plotted respectively,molar concentration ratio of them was determined quantitatively.The experimental results show that p-nitro aryloxy carboxylic acid,because of containing nitro group (—NO_2),will become unstable in the alkaline medium and is easy to take place nucleophilic substitution,and then aryl etherbond is cleaved.The abnormal behaviour which happened in the nucleophilic substitution process of p-nitrophenoxy propionic acid has been discovered,whose extent of etherbond cleavage became the most intensive and substituted products are also abnormal.The mechanism is proposed as an intramolecular nucleophilic substitution by neighboring group participation.

关 键 词：对硝基芳氧酸 亲核取代 对硝基苯氧丙酸 邻基参与 醚键断裂 

分 类 号：O625.322[理学—有机化学]