单基团保护法制备三氯蔗糖的研究

单基团保护法制备三氯蔗糖 ,主要包括活泼C 6位羟基的单基团保护、选择性氯化和去保护基等 3个步骤 ,其中C 6位羟基的单基团保护是核心步骤。研究发现 ,降低温度是对蔗糖C 6位最活泼羟基进行单一选择性保护的有效方法。在 - 2 5℃下 ,蔗糖与乙酸酐 (摩尔比值 0 .95 )反应 6h即可。选择性氯化的最佳反应条件为 :蔗糖 6 乙酸酯 (S 6 a)的质量浓度 15 0mg/L ,S 6 a :Vilsmeier的摩尔比为 1∶7,反应温度 12 5℃ ,反应时间 2 .5h。对氯化产物进行全乙酰化后以三氯 五乙酰基蔗糖酯 (TGSPA)的形式结晶出来 ,再去除保护基 ,可有效减轻分离纯化的压力 ,确保产品纯度和得率。单酯化反应和氯化反应还可合二为一 ,以有效缩短制备路线 ,提高反应的可操作性。本研究通过大量试验确定了具体制备路线 ,并优化了各反应参数 ,三氯蔗糖终产品得率为 8.3%。利用单基团保护法 ,可有效缩短三氯蔗糖的制备路线 ,简化操作过程 ,但对反应条件和分离设备的要求较高

Research on the Monogroup-protected Synthesis of Sucralose

The monogroup protected synthesis method of sucralose contains monogroup protection of C 6 hydroxy,selective chlorination of particular groups and deshielding of protected hydroxy,in which monogroup protection of C 6 hydroxy is the key step.The temperature reduction was shown to be an effective method for the most active C 6 hydroxy mono protection.Sucrose reacted with acetic anhydride for 6h at -25℃.The optimized parameters of selective chlorination were 150?mg/L sucrose 6 acetate(S 6 a),S 6 a∶Vilsmeier=1∶7,125℃ and 2.5h.The chlorinated S 6 a could be crystallized in the form of trichloro pentaacetate(TGSPA)after holo acetylation.The additional process would release the pressure of separation,which is required in the monogroup protected method,and finally increase the productivity.The mono esterification and chlorination can be combined,which can be advantaged to shorten the reaction routes and improve operation.After a lot of experiments,the definite route of preparation and the optimized reaction parameters were determined.And the productivity of sucralose reached 8.3%.With the monogroup protected method,the synthesis route could be shortened and the operation units simplified,although the reaction conditions and separation equipments are requested strictly.