负载型杂多酸催化下N_2O_5对氯苯的选择性硝化

Selective Nitration of Chlorobenzene with N_2O_5 Assisted by Supported Heteropoly Acids

使用负载型杂多酸为催化剂,N2O5为硝化剂的新型硝化体系,对氯苯的硝化反应进行研究。分别考察了杂多酸类型、载体种类、杂多酸负载量及催化剂循环使用次数等因素对硝化反应的影响。结果表明,N2O5硝化反应属于酸催化反应,负载型杂多酸能显著提高N2O5的硝化能力;催化剂回收后可直接重复使用,催化活性没有明显的降低。在优化条件下,氯苯硝化反应得率为26%,对位选择性达68.8%。结果表明,N2O5是一种具有应用前景的硝化试剂,可取代传统的硝硫混酸硝化法,减少废酸处理,符合绿色环保要求。

Chlorobenzene nitration was carried out with supported heteropoly acids as catalysts and N2O5 as nitrating agent. Many factors were investigated, such as kinds of heteropoly acids and carriers, loading of heteropoly acid, number of catalyst used, and so on. Results showed the nitration of chlorobenzene with N2O5 is an acid catalyzed reaction, and the supported heteropoly acids can highly enhance the nitration ability of N2O5 ; the catalyst can be directly reused after recycle, and its activity was not obviously decreased. Under the optimum conditions, the yield of the nitration was 26%, and the para-selectivity was up to 68.8%, which indicates that N2O5 is a prospective nitration agent, and it can replace the concentrated mineral acid as the catalyst which is one of the most environmentally harmful processes, and meets the requirement of green environmental protection.