Method for removing acetic acid from DMF solution of sucrose-6-ethyl ester

Abstract

The invention relates to a method for removing acetic acid from a DMF (Dimethyl Formamide) solution of sucrose-6-ethyl ester. The method comprises the following steps that: firstly, a solution containing DMF, acetic acid, water and sucrose-6-ethyl ester are fed into a dehydrating tower for dehydrating, materials is discharged from a tower kettle and fed into a stripping tower, DMF steam is introduced to enable gas and liquid to be in countercurrent contact in the tower, a DMF-containing sucrose-6-ethyl ester solution is obtained from the tower kettle of the stripping tower, a DMF and acetic acid mixture is obtained from the tower top of the stripping tower, and a pressure swing distillation system is used for separation. DMF with acetic acid removed is obtained at the top of the low-pressure tower, and a part of DMF is heated and vaporized to serve as a steam source of the stripping tower. Tower kettle materials of the low-pressure tower enter a high-pressure tower, a tower top gas phase of the high-pressure tower serves as a dehydrating tower reboiler heat source, heat integration is achieved, and acetic acid is obtained after condensation. The content of acetic acid in the DMF solution at the top of the low-pressure tower can be reduced below 200ppm. The process is simple, does not add a third medium, does not generate solid waste, is energy-saving and environment-friendly, and can realize continuous operation.

Description

technical field [0001] The invention relates to a method for removing acetic acid from sucrose-6-ethyl ester DMF solution, in particular to the removal of acetic acid from sucrose-6-ethyl ester DMF solution involved in the production process of sucralose. Background technique [0002] The industrial synthesis of sucralose is generally based on sucrose as raw material, through transesterification to obtain sucrose-6-ethyl ester, sucrose-6-ethyl ester is chlorinated by Vilsmeier reagent to generate intermediate sucralose-6-acetate, trichloro Sucralose is obtained by deacetylation of sucrose-6-acetate. Among them, sucrose-6-ethyl ester is an important intermediate product in the process of producing sucralose, and a solution of water, acetic acid, dimethylformamide (DMF) and sucrose-6-ethyl ester will be formed during its production. The mixed liquid needs to remove acetic acid and moisture, and then enter the subsequent section of processing with DMF and sucrose-6-ethyl ester...

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Problems solved by technology

[0006] Chinese patent CN107459540A discloses a method to remove acetic acid by adding alkali to neutralize the acid-base reaction until the pH is 6-8. This process will generate sodium acetate as a solid by-product, which increases the difficulty of treatment.

[0007] Therefore, comprehensive prior art method, there is the raw material consumption cost that adds the 3rd kind of medium to bring and the complication of corresponding separation process, and the problem such as difficult handling of the reaction solid product that produces, need to invent a kind of not adding the 3rd kind of medium, does not need to invent Generate solid waste, a new energy-saving and environmentally-friendly method to remove acetic acid from sucrose-6-ethyl ester DMF solution, so that the production process can achieve simple, efficient and environmentally friendly goals

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