A production method for improving the yield and purity of dimethyl isophthalate-5-sulfonic acid for synthesizing three monomers

Abstract

The invention provides a kind of production method that improves three monomer synthesis dimethyl isophthalate-5-sulfonic acid yield and purity, described production method, comprises N 2 Gas purging, adding sulfonated material, adding part of methanol, temperature rise and pressure reaction, adding remaining methanol and catalyst, step temperature rise reaction. The invention reduces the unit consumption of methanol and improves the economic benefits of the product; equivalent to 413-439Kg of methanol consumed per ton of three monomers; the feed amount of methanol is 20% less than that of the existing process; the unit consumption of methanol per ton of three monomers is lower than that of the existing process more than 30%; the purity of dimethyl isophthalate-5-sulfonic acid exceeds 96%, reaching 96.85-97.05%, and the yield exceeds 97%, reaching 97.18-97.42%; the subsequent production of the three-monomer product The rate exceeds 84%; the reaction time is shortened; the esterification reaction operation cycle is shortened by 2 hours compared with the existing production process.

Description

technical field [0001] The invention belongs to the technical field of organic synthesis, and is especially suitable as an important intermediate for synthesizing dimethyl isophthalate-5-sodium sulfonate (commonly known as: three monomers, English abbreviated as SIPM) with isophthalic acid as the starting material Synthesis of dimethyl isophthalate-5-sulfonic acid. Background technique [0002] The synthesis of three monomers with isophthalic acid as the starting material has been produced for decades at home and abroad. The production process is basically divided into the following types: (1) Isophthalic acid is first sulfonated, and then esterified and neutralized , refined, and dried to obtain SIPM, in which the sulfonating agent used is SO 3 , different concentrations of oleum, etc.; the neutralizer used is Na 2 CO 3 , NaOH, sodium sulfite, etc.; (2) esterification sulfonation method, isophthalic acid is first esterified with methanol to produce dimethyl isophthalate,...

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Problems solved by technology

[0018] In view of the low yield, low purity, high reaction temperature, long reaction time and large amount of methanol used in the existing production of dimethyl isophthalate-5-sulfonic acid in China, resulting in the cost of the three monomers of the final product High, many types of impurities and high content, the present invention has carried out in-depth research and optimization on the existing process, forming a new synthetic process

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