CN112079881A

CN112079881A - Method for continuous alcoholysis of sucralose

Info

Publication number: CN112079881A
Application number: CN202011027942.0A
Authority: CN
Inventors: 李恩平; 杨志健; 石剑; 侯方方
Original assignee: Anhui Jinhe Industrial Co Ltd
Current assignee: Anhui Jinhe Industrial Co Ltd
Priority date: 2020-09-26
Filing date: 2020-09-26
Publication date: 2020-12-15

Abstract

The invention relates to a method for continuous alcoholysis of sucralose, which is characterized by comprising the following steps: (1) according to the mass ratio of the sucralose-6-ethyl ester to the methanol of 2.2-3.2: 1, adding sucralose-6-ethyl ester and methanol into a batching tank; controlling the temperature in the material preparation tank to be 30-35 ℃, and stirring and dissolving; (2) adding sodium tert-butoxide and methanol into a catalyst tank to prepare a 2.5-4% sodium tert-butoxide methanol solution; (3) feeding a methanol solution of sucralose-6-ethyl ester and a methanol solution of sodium tert-butoxide into a continuous flow reactor according to a volume ratio of 2.5-3: 1, controlling the reaction temperature at 60-70 ℃, and controlling the pH value of the liquid at the outlet of the continuous flow reactor to be 8.5-9.0; (4) and (3) the liquid from the continuous flow reactor enters a reaction liquid receiving tank, and the content of the sucralose-6-ethyl ester in the liquid in the receiving tank is controlled to be less than 0.5 percent. The invention has the advantages that: by adopting a continuous flow reactor and a continuous feeding mode, the device can continuously and automatically operate, the amplification effect is reduced, and the yield is improved; the catalytic effect of the sodium tert-butoxide is better than that of the traditional sodium methoxide, the conversion rate is high, and the cost of the catalyst is saved.

Description

Method for continuous alcoholysis of sucralose

Technical Field

The invention belongs to the technical field of chemical production, and relates to a method for continuous alcoholysis of sucralose.

Background

Sucralose (TGS), a novel sweetener developed by the british tare company (Tate & ly) and filed in 1976 with the university of london; the sugar-free functional sweetener is a functional sweetener only taking cane sugar as a raw material, the original trade name is Splenda, and the sweetness can reach 600 times that of the cane sugar; the sweetener has the characteristics of no energy, high sweetness, pure sweetness, high safety and the like, and is one of the most excellent functional sweeteners at present.

At present, most of sucralose is industrially produced by a monoester method, namely, DMF is used as a solvent, acetic anhydride is used as an acylating agent to obtain sucrose-6-ethyl ester, thionyl chloride is usually used as a chlorinating agent to carry out chlorination reaction to produce sucralose-6-ethyl ester, and finally, alkaline hydrolysis is carried out in a sodium methoxide solution in a kettle type batch reactor to obtain a sucralose product. The kettle type intermittent reaction is adopted, the technology is seriously lagged behind, and the development of products and the improvement of productivity are restricted.

Disclosure of Invention

The invention aims to solve the problem that a kettle type batch reactor limits the yield of reaction, and provides a method for continuous alcoholysis of sucralose.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a method for continuous alcoholysis of sucralose is characterized by adopting the following devices: the dosing tank and the catalyst tank are respectively connected with the inlet of the continuous flow reactor through pipelines, and the outlet of the continuous flow reactor is connected with the inlet of the reaction liquid receiving tank;

the method comprises the following steps:

(1) according to the mass ratio of the sucralose-6-ethyl ester to the methanol solution of 2.2-3.2: 1, adding sucralose-6-ethyl ester (with the content of 90-95%) and methanol into a batching tank; controlling the temperature of the liquid in the batching tank to be 30-35 ℃, and stirring to completely dissolve the sucralose-6-ethyl ester in the methanol;

(2) adding sodium tert-butoxide and methanol into a catalyst tank to prepare a sodium tert-butoxide methanol solution with the weight concentration of 2.5-4%;

(3) feeding the prepared methanol solution of sucralose-6-ethyl ester and the methanol solution of sodium tert-butoxide with the weight concentration of 2.5-4% into a continuous flow reactor according to the volume ratio of 2.5-3: 1, controlling the reaction temperature of the continuous flow reactor to be 60-70 ℃, and controlling the pH value of the liquid at the outlet of the continuous flow reactor to be 8.5-9.0 (if the pH value is less than 8.5, properly improving the flow of the sodium tert-butoxide solution);

(4) and (3) enabling the liquid from the continuous flow reactor to enter a reaction liquid receiving tank, and controlling the content of the sucralose-6-ethyl ester in the liquid entering the reaction liquid receiving tank to be less than 0.5% so as to ensure the complete reaction.

Further, the content of the sucralose-6-ethyl ester in the step (1) is 93-95%.

Further, the reaction temperature in the continuous flow reactor in the step (3) is 63-68 ℃.

The invention has the following advantages:

1. the invention changes the traditional kettle type process by adopting a continuous flow reactor and a continuous feeding mode, improves the intermittent chemical reaction unit into a continuous operation unit, realizes the continuous automatic operation of the device, reduces the equipment investment and the occupied area, and reduces the construction cost of the device;

2. by using the continuous flow reactor, the reaction temperature and the mixing effect in the continuous reaction process can be finely controlled, the amplification effect is reduced, and the yield is improved;

3. by adopting the device, continuous and automatic operation can be realized, excessive personnel are prevented from participating in the production of the device, the labor is saved, the labor cost is reduced, and the safety of the device is improved;

4. the continuous and automatic operation process can reduce manual operation errors, improve the production stability, indirectly improve the average yield of the reaction, reduce the consumption and save the cost.

5. The sodium tert-butoxide is used as the catalyst, the catalytic effect of the catalyst is better than that of the traditional sodium methoxide (the alkaline effect of the sodium tert-butoxide is stronger than that of the sodium methoxide), and the catalyst can achieve better catalytic effect by adopting lower concentration, thereby being beneficial to the improvement of the conversion rate and saving the use cost of the catalyst.

Drawings

FIG. 1 is a schematic diagram of a process for continuous alcoholysis of sucralose.

Detailed Description

The invention is further illustrated with reference to fig. 1:

an apparatus for continuous alcoholysis of sucralose, comprising: the dosing tank and the catalyst tank are respectively connected with the inlet of the continuous flow reactor through pipelines, and the outlet of the continuous flow reactor is connected with the inlet of the reaction liquid receiving tank.

Example 1

(1) 1000kg of sucralose-6-ethyl ester (with the content of 93 percent) and 2700L of methanol are added into a batching tank; starting a circulating pump, heating the solution by a heater, controlling the temperature of the solution to be 31 ℃, and stirring the solution to completely dissolve the sucralose-6-ethyl ester in the methanol;

(2) adding 3kg of sodium tert-butoxide and 1000L of methanol into a catalyst tank, stirring, and preparing into a sodium tert-butoxide methanol solution with the weight concentration of 3%;

(3) pumping the prepared methanol solution of the sucralose-6-ethyl ester into a continuous flow reactor at the flow rate of 1000L/h;

pumping a sodium tert-butoxide methanol solution into the continuous flow reactor at a flow rate of 330L/h, controlling the reaction temperature of the continuous flow reactor at 65 ℃, and detecting the pH value of liquid at the outlet of the continuous flow reactor to be 8.8;

(4) in the reaction liquid receiving tank, the residual amount of sucralose-6-ethyl ester was sampled and detected to be 0.3 wt%.

Example 2

(1) 1000kg of sucralose-6-ethyl ester (with the content of 92%) and 2900L of methanol are added into a batching tank; starting a circulating pump, heating the solution by a heater, controlling the temperature of the solution to be 34 ℃, and stirring the solution to completely dissolve the sucralose-6-ethyl ester in the methanol;

(2) adding 3.1kg of sodium tert-butoxide and 1000L of methanol into a catalyst tank, stirring, and preparing into a sodium tert-butoxide methanol solution with the weight concentration of 2.8%;

(3) pumping the prepared methanol solution of the sucralose-6-ethyl ester into a continuous flow reactor at the flow rate of 1200L/h;

pumping a sodium tert-butoxide methanol solution into the continuous flow reactor at the flow rate of 300L/h, controlling the reaction temperature of the continuous flow reactor at 68 ℃, and detecting the pH value of liquid at the outlet of the continuous flow reactor to be 8.6;

(4) in the reaction liquid receiving tank, the residual amount of sucralose-6-ethyl ester was sampled and detected to be 0.2 wt%.

Comparative example 1:

(1) 1000kg of sucralose-6-ethyl ester (with the content of 93.1%) and 2700L of methanol are added into a reaction kettle;

(2) starting stirring, heating the reaction kettle to 65 ℃, and dropwise adding 30 wt% of sodium methoxide solution;

(3) keeping the temperature for 2.5h, controlling the pH value of the liquid in the reaction kettle to be 8.8, and finishing the reaction when the residual quantity of the sucralose-6-ethyl ester is detected to be less than 0.55 percent.

Claims

1. A method for continuous alcoholysis of sucralose is characterized by adopting the following devices: the dosing tank and the catalyst tank are respectively connected with the inlet of the continuous flow reactor through pipelines, and the outlet of the continuous flow reactor is connected with the inlet of the reaction liquid receiving tank;

the method comprises the following steps:

(1) according to the mass ratio of the sucralose-6-ethyl ester to the methanol solution of 2.2-3.2: 1, adding sucralose-6-ethyl ester and methanol into a batching tank; controlling the temperature of the liquid in the batching tank to be 30-35 ℃, and stirring to completely dissolve the sucralose-6-ethyl ester in the methanol;

(3) feeding the prepared methanol solution of the sucralose-6-ethyl ester and the methanol solution of the sodium tert-butoxide with the weight concentration of 2.5-4% into a continuous flow reactor according to the volume ratio of 2.5-3: 1, controlling the reaction temperature of the continuous flow reactor to be 60-70 ℃, and controlling the pH value of the liquid at the outlet of the continuous flow reactor to be 8.5-9.0;

(4) and (3) enabling the liquid from the continuous flow reactor to enter a reaction liquid receiving tank, and controlling the content of the sucralose-6-ethyl ester in the liquid entering the reaction liquid receiving tank to be less than 0.5%.

2. The method of claim 1, wherein the continuous alcoholysis of sucralose is performed by: the content of the sucralose-6-ethyl ester in the step (1) is 90 to 95 percent.

3. The method of claim 1, wherein the continuous alcoholysis of sucralose is performed by: the content of the sucralose-6-ethyl ester in the step (1) is 93 to 95 percent.

4. A method for the continuous alcoholysis of sucralose according to any one of claims 1-3, wherein: the reaction temperature in the continuous flow reactor in the step (3) is 63-68 ℃.