Application
4,5-Dimethyl-1,3-dioxol-2-one is a kind of important medicine intermediate, is mainly used in the modification of many medicines, to synthesize, has optically active chiral drug, thereby improves largely drug effect, reduces drug side effect.
Synthesis
1. distillation column is being housed, air set pipe, mechanical stirrer, add 3-hydroxy-2-butanone 88g, methylcarbonate 90g, tirethylene glycol dme 264g and sodium propylate 0.88g in the three-necked flask of thermometer, at 60-65 ℃ of reacting by heating mixture, carry out transesterification reaction 6h, the methyl alcohol of generation is removed in synchronous distillation, obtains carbonic acid monomethyl 3-hydroxy-2-butanone base ester.
2. improve reaction mixture temperature to 110-115 ℃, keep this thermotonus 5h, continue to steam the by products such as methyl alcohol.
3., after reaction finishes, reaction mixture is to room temperature, add concentrated hydrochloric acid with the neutralization reaction catalyzer to reaction mixture pH value in 7 left and right. After methylcarbonate is reclaimed in fractionation, the underpressure distillation aliphatic ether is appropriate.The distillation residuum is cooled to 0-5 ℃, and crystallization, filtration, obtain product 4,5-dimethyl-1,3-dioxole-2-ketone crude product 62.34g.
4. add recrystallization solvent and 0.62g gac in crude product, be heated to 80 ℃ of return stirring 0.5-1h, filtered while hot, filtrate 60 ℃ of lower evaporation concentration to after having mass crystallization to separate out, adopt cooling bath cooling concentration liquid to 0-5 ℃, the gained solids is dried 2h at 50 ℃ of lower normal pressures.
Can obtain highly purified 4,5-Dimethyl-1,3-dioxol-2-one white crystal, these are highly purified 4 years old, 5-dimethyl-1, the quality of 3-dioxole-2-ketone is 53.88g, yield is 47.26% (calculating with the 3-hydroxy-2-butanone), purity (high performance liquid chromatography) is 99.0%, and fusing point is 77-78 ℃.
