Method for increasing yield of 5-sulfoisophthalic acid for synthesis of ternary monomer

Abstract

The invention provides a method for increasing yield of 5-sulfoisophthalic acid for synthesis of a ternary monomer. The method comprises the following steps: feeding, filling nitrogen, performing a first-stage heating reaction, performing a second-stage heating reaction, adding remaining oleum, performing a third-stage heating reaction, and performing a negative pressure reaction. The method has the beneficial effects that the reaction time is shortened, and the reaction temperature is lowered; compared with the existing production process, the maximum reaction temperature is lowered by 30 DEGC, and the sulfonation reaction cycle is shortened by 2 hours; the loss of sulfur trioxide is reduced, the cost is reduced, and the economic benefits of the ternary monomer product can be increased;the amount of oleum is reduced, which is 5% less than that in the current process dosage, and the amount of alkali used in the subsequent neutralization process can be reduced by more than 5%, at thesame time, the reaction time of the neutralization process is shortened, the amount of cooling water is reduced, and the energy saving effect is remarkable; and the yield of 5-sulfoisophthalic acid isincreased.

Description

technical field [0001] The invention belongs to the technical field of organic synthesis, and in particular relates to the synthesis of isophthalic acid-5-sulfonic acid, an important intermediate when isophthalic acid is used as a starting material to synthesize a trimonomer. Background technique [0002] Using isophthalic acid as the starting material to synthesize the three monomers (chemical name: dimethyl isophthalate-5-sodium sulfonate, abbreviated as SIPM), the production methods are basically divided into There are the following types: (1) sulfonic acid crystallization method, sulfonate isophthalic acid with sulfur trioxide or oleum, and then dilute the sulfonated mother liquor with ice water to a sulfuric acid mass fraction of 50%-70%, The sulfonic acid is crystallized, and then the excess waste acid is removed, and excess methanol is used for esterification, and then neutralized and refined to obtain SIPM; (2) Esterification and sulfonation method, isophthalic acid ...

AI Technical Summary

Problems solved by technology

[0017] For the synthesis of isophthalic acid-5-sulfonic acid from isophthalic acid and oleum in China, the yield is low, the reaction temperature is high, the reaction time is long, and the ratio of raw materials is unreasonable, resulting in high cost of the final product three monomers , high impurity content, etc., the present invention conducts in-depth research on material ratio, reaction temperature and time, etc., optimizes the existing process, and forms a new process

Images