Study On Synthesis Process Of Sucralose

Sucralose is derived from sucrose by replacing the hydroxyls in the 4,1′,6′positions with chlorine(in the process of making sucralose, the stereo configuration at the 4 pposition is reversed). It is a kind of high intensity sweetener with significant characteristics and it has many characteristics: high sweetness, excellent sweet characteristics, nonabsorption to body, stability in physics-chemical properties and extensive application etc.There is disclosed a process for preparing sucralose by using monogroup protection. These researches included the following:1. The method of using triethyl orthoacetate is an effective method of preparing sucrose 6-acylates for protection 6-position hydroxyl group. Sucrose 6-acylates, key intermediates in the preparation of sucralose, can be prepared by subjecting a sucrose alkyl 4,6-orthoacylate to mild aqueous acidic hydrolysis to provide a mixture of sucrose 4- and 6- acylates and then treating the mixture with a base to convert the 4-acylate to the 6-acylate. The novel sucrose alkyl 4,6-orthoacylate are prepared by reacting sucrose in solution or suspension in DMF solvent with a trialkyl orthoacrylate in the presence of p-toluene sulphonic acid catalyst at room temperature. The optimum reaction condition was : the mole ratio of triethyl orthoacetate and sucrose(1.4:1), toluene p-sulphonic(6mg/g sucrose), water(10 ml/100mlDMF), t-butylamine(2.5ml/100mlDMF).2. Selecting chlorination of hydroxyl group in sucrose 6-acylates is a key in the process of making sucralose. Sucrose-6-acetate, prepared by using triethyl orthoacetate without crystallization, could be chlorinated by Vilsmeier reagent which was subjected thionyl chloride to DMF. This method had many advantages: high yield, easy operation and easy process. Optimum condition was: reaction temperature (115℃), the mole ratio of SOCl2 and sucrose 6-acylates (10: 1), the ratio of DMF(ml ) and sucrose 6-acylates (g) (12: 1), reaction time(3h ). The structure of the last compound was confirmed by using melting point mensuration, IR and 1H-NMR.3. Sucralose-6-acetate deacetylation preparing sucralose. Purified sucralose-6-acetate which had been recrystallized was hydrolyzed in th system of sodium methoxide/methanol solution, and the mixture was quenched with H+ ion exchange resin, and cake was washed with methanol. The eluate was concentrated to remove methanol and methyl acetate. The aqueous solution was decoloured with active carbon. The filtrate solution was concentrated and crystallized above 38℃for sever hours, the product sucralose was collected. The recrystallization of sucralose-6-acetate using ethyl acetate and water could achieve the sucralose purity above 98%. The structure of the last compound was confirmed by using melting point mensuration, elementary analysis, IR and 1H-NMR.