Study On The New Synthesis Technology Of δ-valerolactone Using Hydrogen Peroxide By Indirect Catalytic Oxidation

As an important fine chemical intermediate, δ-valerolactone has a wide range ofuses in the preparation of fibre (polyester), pharmaceutical material and cropprotection reagent. At present, the demand of δ-valerolactone in our country is mainlyrely on imports, and there was only a very few companies producing δ-valerolactonein the international arena. In recent years, with the broadening use of δ-valerolactone,the market demand has been increasing accordingly, especially in the aspect ofmedical use and environmental protection. Therefore, the existing productiontechnology must be reformed. And it is of great significance to develop a newsynthesis route which has the mild reaction and good economic benefit. Thoughδ-valerolactone could be synthesized in many ways and from many materials, theBaeyer-Villiger oxidation of cyclopentanone into δ-valerolactone attracts moreinterest.Traditional liquid acid catalyst presents the disvantage of having severecorrosion of equipment, though it has good catalytic effect. What’s more, it is difficultto be recovered. With the increasing awareness of environmental protection in recentyears, such catalysts have been abandoned by scientific research workers. Instead, thesolid acid catalyst, has the advantages of being recovered easily, simplepost-processing and less pollution to the environment. Therefore, more and moreattention have been paid on the study of solid acid catalyst.In this experiment, we explored a new synthesis technology of δ-valerolactonestarting from the aqueous hydrogen peroxide containing30%H2O2, propionic acidand cyclopentanone under the solid acid catalysis. Besides, the cyclohexane was usedas water carrying agent.The supported SnO2or WO3catalysts with γ-Al2O3as supports for catalyticoxidation of cyclopentanone to δ-valerolactone were prepared. The catalysts werecharacterized by means of XRD. And through their catalytic performances in thesynthesis of δ-valerolactone, SnO2/γ-Al2O3catalyst prepared by co-calcination wasproved to be the most suitable catalyst for this experiment. Through the single-factorand orthogonal designs and using the titration method for quantitative analysis of thereaction products, the optimal technology conditions in the first step were determinedas follows: the reaction vacuum degree was0.066MPa, the reaction time was4.5h,n(propionic acid): n(hydrogen peroxide)=4.5:1, the amount of catalyst was0.8g. Then under the optimized conditions, the experiment were repeated two times, and theaverage yield and selectivity were31.27%and53.87%respectively.Then on the basisof the first step of synthesizing perpropionic, cyclopentanone was added in tosynthese δ-valerolactone, and the products were quantitative analysed by gaschromatographic. Through the single-factor and orthogonal designs, the optimaltechnology conditions in the second step were determined as follows: the amount ofcyclopentanone was2.1g, the reaction time was3.5h, the reaction temperature was55℃. Then under the optimized conditions, the experiment was repeated three times,and the average yield was49.30%. To our satisfication, the catalyst could berecovered by simplefiltration and repeated three times.The product with high purity was obtained through vacuum distillation. Throughcharacterized and analysed by infrared spectrum and nuclear magnetic resonancespectrum, the synthesized product was proved to be the target productδ-valerolactone.