Study On The Synthetic Process Of The Sweetner-sucralose

The thesis taking sucrose and other organic reagent as raw materials adopts mono-group protection method to synthesize sucralose, researches systematically the synthesis process and analytical method, reviews the major reactive factors of every steps and gains optimized process conditions. The study on qualitative analysis of Thin Layer Chromatogram and quantitative analysis of Column Chromatography to sucrose-6-acetate, sucralose-6-acetate and sucralose is made.The thesis employs separately two esterification reagents- trimethyl ortho-acetate and dibutyltin oxide/acetic anhydride to synthesize sucrose-6-acetate. Comparing the two results, the latter with less reactive by-products, simple separation method and high yield of sucrose-6-acetate can recover and reuse the catalyst and solvents though the reactive device requirements and energy consumption are high. It is more perfect method to synthesize sucrose-6-acetate.By the means of mono-factor experiment, the proper conditions employing dibutyltin oxide/acetic anhydride are defined as follows: the mole ratio of dibutyltin oxide and sucrose is 1.1:1.0; the reflexive temperature is 90℃; the reflexive time is 6h; the mole ratio of acetic anhydride and sucrose is 1.0:1.0 and on this condition the yield of sucrose-6-acetate can reach 80.0%.The chlorination of sucrose-6-acetate adopts separately two chlorination reagents- thionyl chloride and Vilsimier Reagent. The two results indicate that the method with Vilsimier Reagent is more effective, well-selective and productivity-higher than that of thionyl chloride..By the means of mono-factor experiment, the proper conditions taking solid phosgene as chlorination reagent are defined as follows: the mole ratio of solid phosgene and sucrose-6-acetate is1.5:1.0; the reaction temperature is 110℃; the reaction time is 2h; the volume ratio of toluene and DMF is 2.0:1.0. On this condition the yield of sucralose-6-acetate can reach 45.9%.The study on the process for sucralose-6-acetate to eliminate acetyl indicates that the direct elimination process in the chlorination reactive solution is more perfect than the elimination process after the separation of crystal sucralose-6-acetate. The direct elimination process conditions in the chlorination reactive solution are gained by experimental investigation: the pH of the solution is 13; the reactive temperature is 5℃; the reactive time is 2h. On this condition the whole yield can reach 45.6%. The purity is above 98% measured by high pressure liquid chromatogram.The study on qualitative analysis of Thin Layer Chromatogram and quantitative analysis of Column Chromatography shows that the developing solvent analyzing sucrose-6-acetate is acetone- tetrahydro-furan-water solution(the volume ratio is 4:10:1); the developing solvent analyzing sucralose-6-acetate is chloroform-methanol solution (the volume ratio is 2:1); the developing solvent analyzing sucralose is acetic ether-ethanol solution(the volume ratio is 10:1). These all reach the separation requirement.