.4,5 - Dimethyl-1 ,3 - Dioxane Pentene -2 - Ketone Synthesis Process Research

In this paper, the synthesis ways and applications of 4,5-dimethyl-l,3-dioxolen -2-one(DMDO) were introduced. An appropriate way synthesizing DMDO from acetoin via acylation, cyclization and dehydrochlorination was selected. The influences of various process conditions on the reaction were studied in detail, and the optimum process conditions were obtained by single factor experiments.The optimum process conditions of synthesis of the acylating intermediate from acetoin and phosgene were as follows: depolymerization time of acetoin 2 hours, reaction temperature 5~15#, the mole ratio of acetoin to phosgene 1:1.5, the mole ratio of acetoin to antacid 1:1.5, the mass ratio of acetoin to solvent C2H4C12 1:10, reaction time 2~3 hours, and the washing conditions were as these: amount of water 2 mL - g-1, temperature between 0# and 5#. It was found that the yield of acylation was over 90%. In allusion to the special properties of the acylating intermediate, a chemical analysis method was set up to determine the product. The determined conditions were stable, reliable, and could direct effectively the study of process conditions.The optimum conditions of synthesis of DMDO was obtained as follows: water content of acylating product less than 0.05%. reflux cyclization time 3~4 hours, dehydrochlorination temperature 140-160# and time 3 hours. Under this conditions, the yield was over 90% and the purity of the product was above 98%. The analysis method to determin DMDO was GC, the method was easy to operate and it was accurate.The created dot of the paper was that the synthesis process for preparing DMDO from phosgene was improved. The optimum process conditions were obtained by single factor experiments and the product yield arrived to and above that of reports of reference. The technical data and reliable basis for producing DMDO were provided.