Optimization Study On Synthesis Conditions And Isolation Method Of Dehydroacetic Acid

Dehydroacetic acid is a new type of food antiseptic, which has broad- spectrum,strong antibiotic action, high stability and security. It was used in food industry extensively.The DHA was synthesized with the catalyst by two methods in this paper. The influences of reaction time, reaction temperature and the amount of catalyst have been studied. The optimized reaction conditions were obtained. When the raw material is acetoacetic ester, the optimized reaction temperature is 200℃,the optimized reaction time is 6hr, the optimized catalyst is NaHCO3+Na2CO3, and the yield is 43.1%. When the raw material is diketene, the optimized catalyst is triethlenediamine, the optimized reaction temperature is 40℃, the optimized reaction time is 80 min, and the yield is 83.6%. The traditional purification in industry is reduced pressure distillation. Because of its low melting point, the product often jam the line of pipes, so some people purify the product by recrystallization. The recrystallization also has defaults; the product has lower purity, so it is difficult in food. In this paper, we purify the product by using hot water extration and water vapor distilation.The product gained is high purity, its purity is above 99%, and the method is simple.The product has been analyzed by IR, 1HNMR, etc, and the result reviews the product is dehydroacetic acid.Ultraviolet spectrophotometric method and chromatography are often used in the analysis of dehydroacetic sodium. But those methods need exorbitant equipment, operation is difficult, and it only has been used in microanalysis. The method of commercial product's analysis is not reported. In this paper, we found a method of commercial product's analysis by using nonaqueous titration. In this method, the p- naphtholbenzene is used as indicator. This method can be used as quality control in industry.In the test of dehydroacetic acid's performance, it reveals excellent antiseptic capability.