Production method for improving yield and purity of dimethyl isophthalate-5-sulfonic acid for synthesis of sodium dimethyl isophthalate-5-sulfonate

Abstract

The invention provides a production method for improving the yield and purity of dimethyl isophthalate-5-sulfonic acid for synthesis of sodium dimethyl isophthalate-5-sulfonate. The production methodcomprises the steps: performing purging with N2 gas, adding a sulfonation material, adding a part of methanol, raising the temperature and pressure for a reaction, adding the remaining methanol and acatalyst, performing step raising of temperature for a reaction. The unit consumption of methanol is reduced, the economic benefit of the product is improved, and the consumption of methanol per ton of sodium dimethyl isophthalate-5-sulfonate is 413-439 Kg; the amount of the fed methanol is reduced by 20% compared with that of an existing process, and the unit consumption of methanol per ton of the product sodium dimethyl isophthalate-5-sulfonate is reduced by 30% or above compared with that of the existing process; the purity of dimethyl isophthalate-5-sulfonic acid exceeds 96%, and reaches 96.85-97.05%, the yield exceeds 97%, and reaches 97.18-97.42%, the yield of the sodium dimethyl isophthalate-5-sulfonate product produced in subsequent continuous production exceeds 84%, and the reaction time is shortened; and the operation cycle of an esterification reaction is shortened by 2 hours compared with that of 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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