Optimization Of Synthesis Technology Of DL-?-hydroxy-?,?-dimethyl-?-butyrolactone

DL-a-hydroxy-?,?-dimethyl-y-butyrolactone is the key intermediate in the synthesis of calcium pantothenate, panthenol and other products. In the synthesis of DL-a-hydroxy-?,?-dimethyl-y-butyrolactonel, the condensation reaction of isobutylaldehyde and formaldehyde preparing hydroxypentylaldehyde in the presence of triethylamine is the key process. The traditional single pot process has high energy consumption, the output is limited by the equipment, and the proportion of single batch reaction is unstable. It was reported that the tubular reactor possessed many advantages such as small volume, big specific surface area, large unit volume heat transfer area and large production capacity, and so on. Also, the residence time of the reactants in the tubular is equal, and the obtained product quality is stable. In this work, the tubular reactor was chosen to carry out the condensation reaction of isobutylaldehyde and formaldehyde preparing hydroxypentylaldehyde was effective process.It was helpful to the energy conservation and emissions reduction, improving product quality and stability.The yield of the obtained hydroxypentylaldehyde was investigated starting from isobutylaldehyde and formaldehyde using triethylamine as a catalyst by designing orthogonal experiment and the law experiment. The optimal synthesis process was determined. The synthesized desired product was characterized by IR and MS.Besides, the obtained optimal synthesis process was applied to the actual production of the tubular reactor. The preheating mixing section, reaction section, cooling section of the whole reaction process in the tubular reactor were accurate controlled. And each segment of the reaction temperature, reaction time and group allocation ratio of the cross experiment was examined by the orthogonal experimental design method and single factor method. The best technological conditions were obtained by mixing the temperature of the mixing section:70?, the reaction temperature 115? and the reaction temperature:40-50?, the reaction time: 4h, the distribution ratio of the group n(Isobutylaldehyde):n(formaldehyde):n (triethylamine)=1:1:0.04. Compared to the traditional single pot process, the yield was enhanced from 92% to 98%. The volume of the equipment and the production capacity is greatly improved, the fluctuation of the reaction is stable. Inadditionally, the producing efficiency was improved, and the consumption was significantly reduced.