Method for preparing sucralose-6-ester by utilizing phase transfer catalyst to catalyze and chloridize

Abstract

The invention discloses a method for preparing sucralose-6-ester by utilizing a phase transfer catalyst to catalyze and chloridize. The method comprises the following steps: adding the phase transfer catalyst in a prepared Vilsmeier reagent, and dropwise adding a DMF (Dimethyl Formamide) solution of sucrose-6-ester at 5-10 DEG C; raising the temperature to 45-55 DEG C, and keeping the temperaturefor 1-1.5 hours; raising the temperature to 75-85 DEG C, and keeping the temperature for 1-1.5 hours; raising the temperature to 108-109 DEG C, keeping the temperature for 2.5-3 hours, reducing the pressure, concentrating and evaporating a chlorine-containing solvent; reducing the temperature of material liquid to room temperature; and introducing ammonia, thereby neutralizing. The method provided by the invention has the beneficial effects that the energy consumption can be reduced, the low-temperature reaction is stable and safe, the final temperature of the reaction is low and the generation of by-products is reduced. During a treating process after chloridizing the material liquid, the ammonia is introduced for neutralizing, thereby achieving zero carried water and reducing the decomposition and loss of the sucralose-6-ester. Meanwhile, the recycling cost of the solvent DMF is lowered, the energy consumption during production is reduced, and the phase transfer catalyst is used forboosting the efficient dissolving of the raw material and causing the chlorination reaction to be stably and efficiently carried out.

Description

technical field [0001] The invention relates to the technical field of preparation of sucralose, in particular to a method for preparing sucralose-6-ester by catalytic chlorination of a phase transfer catalyst, Background technique [0002] In the preparation of sucralose, the monoester method is widely used in industry. The process is as follows: first convert sucrose into sucrose-6-ester, then chlorinate sucrose-6-ester to obtain sucralose-6-ester, and then alcoholyze to obtain sucralose. Among them, the chlorination of sucrose-6-ester is a key step, and the chlorination method is extremely important. Vilsmeier reagent is usually used in the chlorination of sucrose-6-ester. Vilsmeier reagent is prepared by the reaction of thionyl chloride or solid phosgene with DMF. During the reaction of Vilsmeier reagent and sucrose-6-ester, Vilsmeier reagent The solution with sucrose-6-ester cannot be miscible well, and the reaction is difficult to form a homogeneous reaction, so that...

AI Technical Summary

Problems solved by technology

Vilsmeier reagent is usually used in the chlorination of sucrose-6-ester. Vilsmeier reagent is prepared by the reaction of thionyl chloride or solid phosgene with DMF. During the reaction of Vilsmeier reagent and sucrose-6-ester, Vilsmeier reagent The solution with sucrose-6-ester cannot be miscible well, and the reaction is difficult to form a homogeneous reaction, so that the reaction cannot be carried out smoothly. Therefore, when adding the DMF solution of sucrose-6-ester dropwise, the temperature is required to be lower than 5 ° C. At the same time After the DMF solution of sucrose-6-ester is added dropwise, it takes a long time (generally 10-13 hours) for the feed liquid to rise from 5°C to 110°C. Slowly increase the temperature in stages to prevent unsafe reactions caused by unstable reactions At the same time, the final temperature of the reaction can be effectively converted into sucralose-6-ester when the final temperature of the reaction is above 110°C, and the reaction must be kept at 110°C-113°C for 3 hours, so that the higher temperature and long-term reaction process will cause more By-products are formed, the carbonization of the material in the final feed liquid is serious, and there are many dark black gelatinous substances

Leading to a decrease in production yield and difficulty in post-treatment of feed liquid

[0003] In addition, when post-processing after chlorination is completed, generally 30% liquid caustic soda is used to neutralize the feed liquid, and this processing method has defects

Because of the use of liquid caustic soda, a large amount of water is brought into the feed liquid, which can cause hydrolysis side reactions. In addition, due to miscibility with water, dimethylformamide (DMF) is not only difficult to recover, but also part of the aqueous phase will be taken away during extraction. Chlorinated products