磷酸二氢钠催化下甲苯的区域选择性硝化

研究了磷酸二氢钠催化甲苯硝化反应的催化活性,通过气相色谱考察了催化剂用量、反应时间、硝化反应温度及催化剂的重复使用等因素对甲苯转化率和产物区域选择性的影响。实验结果表明,在醋酐存在条件下,以CCl4为溶剂,质量分数为95%的硝酸为硝化剂,反应温度55℃,反应60min,1.0g磷酸二氢钠为催化剂,甲苯硝化表现出强的区域选择性,甲苯硝化产物邻对位摩尔比达1.16,较硝硫混酸的1.67显著降低,产物得率达到100%。该催化剂循环使用5次后,催化活性变化很小,产率仅下降0.1%。

Regioselective Nitration of Toluene with Nitric Acid in the Presence of Sodium Dihydrogen Phosphate Catalysts

Catalytic activities and regioselectivities of sodium dihydrogen phosphate for nitrations of toluene were investigated by gas chromatography.The results show that,when the nitration temperature is controlled at 55 ℃,and the reaction time is 60 min,using 95% nitric acid as nitrating agent in the presence of acetic anhydride and 1.0 g sodium dihydrogen phosphate as catalyst,nitration of toluene shows high regioselectivity,up to ortho-para isomer mol ratio of 1.16 in the product,much lower than the ratio of 1.67 when mixed nitric and sulfuric acids are used as nitrating agent.The yield is 100%.The catalyst can be reused up to five times with little change in activity,and the yield only decreases by 0.1%.