Synthesis Of 1,1-Dimethoxy-2-propanone

1,1-Dimethoxy-2-propanone is an important intermediate for the synthesis of vitaminA, β-carotene, canthanthin, astaxanthin and 4-methylimidazole. It is widely used in the synthesis of vitamins and many kinds of drugs. In this paper, we choose 1,2-propylene glycol as the raw material and get the aimed product 1,1-dimethoxy-2-propanone via catalyst oxidation and acetalation. The route has such advantages as easy material, short steps, less pollution and high yield.In this paper, the structures of methylglyoxal and 1,1-dimethoxy-2-propanone are identified by GC-MS, NMR and the standard samples. The reaction conditions of catalyst oxidation and acetalation according to reaction mechanisms are discussed. Four types of catalysts are prepared. At the same time, all kinds of catalysts are evaluated and get the conclusion that ZN-1-F is the best catalyst. On the base of ZN-1-F catalyst, the effects of temperature, oxygen to 1,2-propylene glycol ratio, 1,2-propylene glycol space velocity (SV) and 1,2-propylene glycol to water ratio on catalyst oxidation are discussed. The optimized conditions of the first reaction are: temperature is 410°C,the optimized oxygen to 1,2-propylene glycol ratio is 1.6, the optimized SV is 12h-1 and the optimized 1,2-propylene glycol to water ratio is 1:1(w/w). During the catalyst oxidation, 98.4% 1,2-propylene glycol can be converted and the selectivity is 82.2%. The catalyst life-span is 90 days. At the same time, Catalyst reaction net is analysed in this paper and we deduce some possible reactions. As for acetalation, we research the effects of acid kinds, acid quantity, temperature solvents on it and get the conclusions that the optimized acid is sulfuric acid, the optimized temperature is 65 °C, the reaction time is five hours, and the material ratio of sulfuric acid to methylglyoxal to methanol is 0.028:1:6.837(mole ratio). The acetalation yield is 81%. At the same time, we identified the main byproducts in this step.