无溶剂、微波下固体碱催化酚的乙酰化反应

Acetylation of Phenols Catalysized by Solid Bases under solvent-free

摘要:

采用浸渍法和微波辐射法制备得到了几种以介孔氧化铝为载体的负载型固体碱催化剂。比较了这些负载型固体碱及相应无负载固体碱于无溶剂条件下对苯酚的乙酰化反应的催化效果，其中微波辐射法制备得到的碳酸钾-氧化铝（固体碱III-3）效果最好。同时对固体碱III-3催化的苯酚乙酰化反应进行条件优化，得出较优催化剂用量相对苯酚的摩尔百分比为16.8mol%、温度60℃时产率94.8%。并研究了固体碱III-3于无溶剂条件下传统加热和微波加热下对取代苯酚的乙酰化反应的催化效果，结果显示，采用传统加热法，反应时间150 min时乙酰化收率在62.0%~99.8%；而在微波辐射下，反应9 min时乙酰化收率即可达76.4%~100.0%。因此无溶剂条件下采用微波加热法用固体碱III-3催化酚的乙酰化反应是有效可行的。

Abstract:

Supported solid base K2CO3/Al2O3 prepared under microwave irradiation were found to be an efficient catalyst for the acylation of phenols with acetic anhydride in high yields under solvent-free conditions and under microwave irradiation in a short reaction time. The catalysis efficacy of supported solid bases prepared under microwave irradiation, dipping and non-supported solid bases were investigated in the acylation of phenols with acetic anhydride at room temperature. It’s found that K2CO3/Al2O3 (III-3） prepared under microwave irradiation has the best catalysis in the solid bases in the reaction. Optimized the conditions of acetylation of phenol with K2CO3/Al2O3 (III-3）, the experiment date shows that the best catalyst molar percent to phenol is 16.8mol% ,the best temperature is 60℃, the yield is 94.8% under these optimal conditions. K2CO3/Al2O3(III-3) as a efficient catalyst used in the acylation of various phenol donors was also investigated under microwave irradiation and traditional heating. The yields are 62.0%-99.8% under traditional heating in 150 min; 76.4%-100.0% under microwave irradiation in 9 min. The experimental data indicated that the general applicability and efficiency of this reaction is evident from the wide range of compounds studied. At the same time , microwave irradiation shorten reaction time largely , so it is better than the method of traditional heating.