The Studies Of Solid Acid-base On The Synthesis Of Acetylacetone And Acetylacetone Derivatives

Acid-base catalysis is the most common type of response in organic synthesis,and it has been dominated by an extremely important position in industry.Solid acid-base catalysis,compared with the traditional liquid acid-base catalysis,is easy to separate products and catalyst and recycle catalyst.It also has the characteristics of continuous production which can meet the needs of the current green chemistry and sustainable development.The increasing attention has been paid to it.Acetylacetone and its derivatives get applications in a wide range in many chemical fields.Now the main method for the preparation of acetylacetone is ketene condensation which has the features of large investments,high energy consumption and low yield.The preparation of 3,4-dihydropyrimidinones and 1,4-dihydropyridine also has the disadvantages of unsatisfactory yields,toxic reagents,and long reaction times.Therefore,the synthesis of acetylacetone and its derivatives utilizing solid acid-base is of great significance.This article is about the condensation reaction catalyzed by solid base to get acetylacetone with the resources of acetyl ethyl acetate and acetic anhydride.The synthesis of acetylacetone was catalyzed by solid base and the synthesis of 3,4-dihydropyrimidinones and 1,4-dihydropyridine which were catalyzed by solid acids.The main contents and results are as followings:1.Catalyzed by solid base,acetylacetone was prepared by acetyl ethyl acetate and acetic anhydride.The best solid base MgO/?-Al2O3 catalyst was got.During the reaction,the best method to get solid base was obtained:13.4%selected loading of MgO/?-Al2O3,roasting for 4 hours and the temperature is 500 °C.The acetylacetone was got by acetyl ethyl acetate and acetic anhydride on the surface of high active solid base.This method can avoid effectively the traditional method MgO was so easy to form metal complexes with acetylacetone and got lost serious that it could not be recycled during the reaction.The optimum conditions:1:1(mole ratio)of acetyl ethyl acetate and acetic anhydride,catalyst 1.0%(wt%),reaction time is 7 hours,and the reaction temperature is 125 ?.The yield of acetylacetone was up to 91.6%at the first time and the yield was still up to 90%after reactions of 6 times.This method has the advantages of mild reaction conditions,half of the traditional time;the reaction temperature can be 10 ? lower,simple operation,wide use and recyclables of catalyst.2.A simple and efficient synthesis of 3,4-dihydropyrimidinones or thiones from an aldehyde,1,3-dicarbonyl compound,and urea or thiourea using silica-supported ceric sulfate(Ce(SO4)2-SiO2)as a heterogeneous catalyst at 110 ? under solvent-free conditions is described.The possible mechanism is the form of acyliminum cation which was coordinated with the bond orbital space of cerium ions by urea and aldehyde first,then the open chain ureides was got by condensation reaction with 1,3-dicarbonyl compounds,and the final products were formed by dehydration.Compared with traditional methods,this new method has advantages of good yield,short reaction time and recyclables of catalyst.Nafion-H was used to catalyze one-pot three component condensation reactions of aldehydes,1,3-dicarbonyl compound,and urea or thiourea under ultrasound irradiation to give 3,4-dihydropyrimidinones or thiones in high yields.Compared with traditional methods,mild reaction conditions,ease of work-up,high yields are features of this new procedure.Ce(SO4)2-SiO2 efficiently catalyzed the three-component reaction from 1,3-dicarbonyl compounds,aldehydes,ammonium acetate to afford the corresponding 1,4-dihydropyridine compounds at 80 ? under solvent-free conditions.This method has advantages of excellent yields,ease of work-up,short reaction time,recyclables of catalyst.1,4-dihydropyridine compounds were prepared by 1,3-dicarbonyl compounds,aldehydes,ammonium bicarbonate in the absence of catalyst and solvent under ultrasound irradiation.With the effect of ultrasonic sound,ammonium bicarbonate was stably decomposed into ammonia which produced amino ketene with carbonyl compounds.Then the Michael with another intermediate product and got the final product by dehydration reaction.This method has a simple post-processing with high yields and no environmental pollution.3.Different metal complexes of acetylacetone were prepared by acetyl acetone and various metal salts under ultrasound irradiation.The effects of different bases and radiation time were studied.Compared with traditional liquid-phase methods,this method is easy to work up with high yields and short reaction time.The innovative researches were done on the preparation of acetyl acetone and its derivatives by solid acid-base and the positive results were obtained.Some experimental and theoretical bases were provided in this area.The replacement of traditional liquid acid-base catalysts by solid acid-base which is an important technology will become the pursuit of green chemistry.