对羟基苯乙酮氨肟化制备对羟基苯乙酮肟

考察了在HTS-1分子筛催化剂上对羟基苯乙酮(简写为4-HAP)在固定床反应器中与氨和过氧化氢发生氨肟化反应合成对羟基苯乙酮肟(简写为4-HAPO)的反应规律,4-HAP氨肟化反应的适宜条件为:以乙醇为溶剂、温度高于60℃、反应时间大于5 h、4-HAP宜一次性加入、氨和过氧化氢连续加入、催化剂的质量分数为w(HTS-1)=1.4%、n(NH3)∶n(H2O2)∶n(4-HAP)=4.2∶1.1∶1、n(溶剂)∶n(4-HAP)=6∶1,4-HAP转化率达到73.9%,4-HAPO选择性达到98.9%,该结果优于类似条件下US 5 466 869报道的结果。通过色质联用分析鉴定了4-HAP氨肟化反应的产物,与现有的文献报道相比,HTS-1分子筛具有较高的活性和选择性,副产物的种类和数量均较少。4-HAP氨肟化反应过程中产生的副产物主要为1,8,9-蒽三酚(THA)和对苯二酚(HQ)。适当提高反应温度和催化剂浓度、提高氨与4-HAP的比例、控制过氧化氢与4-HAP在适当的摩尔比(如1.1∶1),可抑制这两种副产物的生成。HQ和1,8,9-蒽三酚在氨存在下发生氧化反应是反应产物颜色变深的原因。

Preparation of 4-Hydroxyacetophenone Oxime by Ammoximation of 4-Hydroxyacetophenone

4-Hydroxyacetophenone oxime(4-HAPO) was prepared by ammoximation of 4-hydroxyacetophenone(4-HAP) with NH_3 and H_2O_2 in the presence of HTS-1 zeolite in a fixed bed reactor system.The suitable operation conditions are:ethanol as solvent,temperature above 60 ℃,reaction time exceeding 5 h,4-HAP added in a lump,NH_3·H_2O and H_2O_2 added continuously,mass percentage of catalyst about 1.4% and n(solvent)∶n(NH_3)∶n(H_2O_2)∶n(4-HAP)=6∶4.2∶1.1∶1.Conversion of 4-HAP and selectivity for 4-HAPO reached 73.9% and 98.9%,respectively,higher than those reported in US 5 466 869.The reaction products of ammoximation were analyzed by GC-MC.The result showed that HTS-1 zeolite provided the reaction with higher activity and selectivity,less kinds and amounts of by-products compared with the reported literatures.The by-products of ammoximation are 1,8,9-trihydroxyanthracene(THA) and hydroquinone(HQ),which can be restrained by raising the reaction temperature and catalyst content properly,increasing the ratio of NH_3 to 4-HAP,and controlling the mol ratio of H_2O_2 to 4-HAP(for example 1.1).Owing to oxidation of THA and HQ in the presence of NH_3,the reaction product became more and more dark-colored.