The Synthesis Of 3-acetyl-6-methyl-2H-pyran-2, 4（3H）-dione Catalyzed By Compound Alkali CaO/Al₂O₃

3-acetyl-6-methyl-2H-pyran-2,4(3H)-dione, is a category of crystalline powder with color of whiteness or canary, whose English name can be abbreviated for DHA. It’s significant toughening agent, intermediate and substrate in the field of chemical industry and also a class of vital preservative which has the advantage of high efficience, low toxicity and broad spectrum. However, the domestic research about its synthesis began later and has a long distance compared with developed countries yet, far from the ability to meet the requirements of China’s factories. The method of ethylacetoacetate is popular and favored by domestic and foreign companies owing to good safety and environmental protection, mild process conditions and simple production operation. Nevertheless, the biggest disadvantage of this method is that the yield of the product is relatively low, and the type of catalyst is the most influential factor. Hence the preparation, inquiry of compound alkali and used as the catalyst in the production of DHA via ethylacetoacetate play an important part in terms of both engineering value and reality.In this paper, the Al2O3 is used as the carrier and CaCl2 as the precursor, and compound alkali catalyst CaO/Al2O3 is prepared by using the method of impregnation. And the effects of the composite base catalyst preparation conditions for example impregnation ratio, calcination temperature and calcination time on the yield of DHA were studied through a series of experiments. The results show that the best preparation conditions are as follows: the impregnation ratio is 7.6%, calcined at 300℃ for 3h. The alkali content and alkali strength, specific area of the composite base catalysts were determined, and the composite base catalysts were characterized by XRD and SEM, too.CaO/Al2O3 compound alkali as the catalyst, ethylacetoacetate as the substrate, the best conditions to synthetize DHA are as follows: the feed rate is 1200μL/min, reaction temperature is 330℃ and reaction time is 2.5h. With the best conditions of the catalyst, the yield of DHA is up to 96.71% at the optimal operation circumstance. The offspring was verified and characterized by the determination of melting point and analysis of IR, MS and 1HNMR.