离子型表面活性剂催化合成4-硝基邻二甲苯的研究

Regioselective Nitration of o-Xylene to 4-Nitro-o-xylene Catalyzed by Surfactants

采用不同的离子型表面活性剂,在硝酸硝化体系中,通过对催化剂种类、催化剂用量以及反应物用量、反应温度、反应时间的优化,得到合成4-硝基邻二甲苯的最佳反应条件。同时采用红外光谱、核磁共振氢谱以及高效气相色谱,对产品进行了表征分析。结果表明,在反应温度为25℃时,n(硝酸):n(邻二甲苯)=3:1,n(十二烷基磺酸钠):n(邻二甲苯)=2:1000,邻二甲苯的转化率达到99.8%,反应选择性超过98%,其中4-硝基邻二甲苯的选择性可达58.8%。

HNO3was employed as highly active nitrating reagents and a host of surfactants as catalysts in the nitration of o-xylene. The reaction conditions for the preparation of 4- Nitro- o- xylene were evaluated including different kind of surfactants as catalyst,the amount of catalyst,reactants ratio of HNO3 and o- xylene,reaction temperature. Meanwhile,the products were characterized and analysised by IR,1H NMR and HPLC. The results showed that under the reaction condition of an catalyst / o- xylene molar ratio of 2： 1000,an HNO3/ o- xylene molar ratio of 3： 1. reaction temperature of25℃ the conversion of o- xylene improved to 99. 8%,and the yield of mononitration product significantly exceed 98%,thereinto the selectivity of 4- Nitro- o- xylene is up to 58. 8%.