Method for preparing 2,5-diparamethylaniline terephthalic acid (DTTA)

Abstract

The invention relates to a method for preparing 2,5-diparamethylaniline terephthalic acid (DTTA) which is prepared by using dimethyl succinate succinyl (DMSS) and 4-toluidine as raw materials. The method comprises the steps of: 1, mixing materials; 2, raising the temperature for dissolving; 3, carrying out condensation; 4, carrying out hydrolysis oxidizing reaction; 5, carrying out solid-liquid separation; 6, absorbing and removing impurities; 7, carrying out solid-liquid separation; 8, neutralizing and acidizing; 10, washing and dehydrating; 11, drying; and 12, crushing and packaging. The product of the DTTA is obtained by the steps. The invention has the advantages of reasonable process, high purity of products, stable quality, high yield and safe and reliable reaction process.

Description

technical field [0001] The invention relates to a compound for preparing organic pigments, which is an important intermediate for the manufacture of quinacridone series organic pigments. Dimethyl succinate DMSS and p-methylaniline TAN are used as raw materials to prepare 2,5-di-p-methylanilino terephthalic acid DTTA through condensation reaction, hydrolysis oxidation reaction and neutralization acidification reaction, which belongs to fine chemical industry technology field. Background technique [0002] Quinacridone pigments are a very important class of high-grade organic pigments, with excellent light fastness, heat fastness, and non-migration in various plastics, so they are widely used in high-grade coatings, engineering plastics, It is also used in the coloring of resin, pigment printing, ink and rubber, and also in the coloring of synthetic fibers, and has broad application prospects. [0003] 2,5-di-p-toluidino-3,6-dihydroterephthalic acid dimethyl ester, (2,5-di-p...

AI Technical Summary

Problems solved by technology

[0013] (1) In the condensation reaction process, DMSS and p-methylaniline TAN are carried out condensation reaction in organic solvents such as methanol, ethanol, because the solubility of DMSS in the solution such as methanol, ethanol is limited, and the boiling point of methanol, ethanol is low , in carrying out condensation reaction process, be difficult to make DMSS thoroughly dissolve, and the product of generation is also solid product, therefore, cause dimethyl succinyl succinate and p-methylaniline condensation reaction process efficiency to be low, and reaction is difficult to carry out thoroughly, Reactants are easily entrained in the solid product produced by the condensation reaction

Furthermore, water H is produced as a by-product during the condensation reaction. 2 O, resulting in difficulties in the recovery of organic solvents, low selectivity and conversion of products, usually in order to increase the operating temperature of the reaction system, usually need to adopt pressure operation, there are potential safety hazards in the operation process;

[0014] (2) in DMSS and TAN through the hydrolysis of condensation reaction product, oxidation reaction process, because the solubility of 2,5-di-p-methylanilino dimethyl terephthalate salt in water or methanol, ethanol aqueous solution Small, resulting in slow hydrolysis oxidation reaction, hydrolysis, oxidation reaction is difficult to complete, in order to obtain 2,5-di-p-methylanilino dimethyl terephthalate salt solution, need to add a large amount of water or alcohol aqueous solution, resulting in process The medium efficiency is low, the amount of wastewater is large, and the treatment is difficult;

[0015] (3) in the process of preparing 2,5-diaminoterephthalic acid in the neutralization acidification reaction of the purified 2,5-di-p-methylanilino terephthalate salt solution after hydrolysis oxidation, because The solution concentration of 2,5-di-p-methylanilino dimethyl terephthalate salt generated after hydrolysis and oxidation is low, resulting in the addition of acid to the refined mother liquor obtained after neutralization and acidification to obtain 2,5- The solid crystal of diaminoterephthalic acid is small, the production efficiency is small, and the product purity is low;

[0016] (4) In all chemical reaction processes, the reaction rate of the general liquid-liquid system is greater than the reaction rate of the liquid-solid system. Therefore, it is really difficult to avoid the solid-solid reaction system, so that the liquid-liquid → produces Liquid-solid, so solid-liquid produces a liquid-liquid reaction system. For the system of solid crystalline materials, in principle, the upper limit of the operating temperature is the boiling point of the lowest solvent, and the lowest operating temperature is the melting point of the highest substance, unless it is necessary to dissolve the crystalline product. In the solvent, because in the current preparation process, methanol and ethanol aqueous solution are mainly used as solvents, so the reaction is difficult to carry out thoroughly, or in order to obtain the same system of solution phase materials, a large amount of solvents need to be used, which makes the recovery of the solvent difficult, and There is a danger of flammability and explosion;

[0018] (6) The amount of waste water produced in the traditional production process is large, difficult to deal with, and serious environmental pollution

Images