氮氧化物和硫化氢常规化学监测法的反应机理

The Reaction Mechanism of Conventional Chemical Monitoring Method for NO_x and H_2S

文章研究了盐酸萘乙二胺分光光度法测定NOx、亚甲基蓝法测定H2S两种常规化学监测方法的反应机理。盐酸萘乙二胺分光光度法测定空气中的NOx经历了反应类型为歧化的吸收反应和重氮化反应、偶合反应三个步骤,歧化反应的产物是HNO2和HNO3;重氮化机理是质子化的亚硝酸和对氨基苯磺酸先生成氮硝基化合物,然后经重排、脱水生成重氮离子;偶合反应的实质是电子云密度较多的萘环和亲电性很强的芳香磺酸重氮离子发生亲电取代反应。硫化氢和对氨基二甲基苯胺作用生成亚甲基蓝的反应经历了亲电取代、脱氨、亲核加成等反应历程。

It is studied in this article the reaction mechanism of two conventional chemical analysis methods,hydrochloric naphthalene ethylenediamine spectrophotometry method for NOx determination and methylene blue method for H2 S determination.Determining NOxin the air through hydrochloric acid naphthalene ethylenediamine spectrophotometry method experiences three steps:disproportionation absorption reaction,diazo-reaction and coupled reaction.HNO2 and HNO3 are the products from disproportionation absorption reaction;diazotization mechanism is that diazonium ions are produced through rearrangement and dehydration after protonated nitrite and sulphanilic acid generating N-nitro compounds; the essence of coupled reaction is that naphthalene nucleus of high electron cloud density and aromatic sulfonic acid diazonium ion of great eletrophilicity conduct electrophilic substitution reaction.The reaction of sulfuretted hydrogen and N,N-Dimethylphenylenediamine producing methylthionine chloride experiences reaction courses of electrophilic substitution,deamination and nucleophilic addition.