甲苯区域选择性硝化的研究进展

综述近20多年来国内外提高甲苯硝化反应区域选择性的各种方法的新进展。通过对各种硝化剂和催化剂的讨论和分析，提出通过提高甲苯硝化产物中对位异构体的比例，可进一步提高甲苯硝化产物的区域选择性，避免大量邻硝基甲苯的产生，改善了硝化反应环境，减少环境污染。将各种分子筛用于甲苯的区域选择性硝化，具有节约能源及原材料、无废酸废水产生、无腐蚀等特点。硝化产物转化率大幅度提高，硝化产物区域选择性好。

Progress on Regioselective Nitration of Toluene

The current progress in all kinds of methods that can increase the regioselectivity of nitration of toluene at home and abroad in the last twenty years is summarized. The requirement of the environmental aspect of regioselective nitration of toluene is analyzed. Through the study of the constitute both of the nitrating reagents and catalysts, the ratio of para isomer of nitro products is improved, the regioselectivity of nitration of toluene is increased, forming of majority of ortho isomer of nitrotuluene is avoided, the environments of nitration of toluene is improved and the environmental pollution that caused by nitrating reaction is decreased. The regioseleetive nitration of toluene with nitrogen oxides in the presence of various sorts of zeolites, can save energy and raw materials, and possesses the characteristics of no waste acid and waste water, and no corroding to the nitro installation. The yield of nitro products is increased by a big margin, nitro products almost is produced quantitatively and high para selectivity is achieved in all these catalysts. The regioselective nitration of toluene with nitrogen oxides over exchanged zeolites is a clean nitration method which has vast prospects.