Synthetic method of 1,2,4,5-cyclohexanetetracarboxylic dianhydride

Abstract

The invention provides a preparation method of 1,2,4,5-cyclohexanetetracarboxylic dianhydride. The method comprises the following steps: pyromellitic acid is reacted with an esterification reagent to prepare pyromellitic acid ester; pyromellitic acid ester is hydrogenated in a fixed-bed reactor to synthesize hydrogenated pyromellitic acid ester; the obtained hydrogenated pyromellitic acid ester is Efficient synthesis of 1,2,4,5-cyclohexanetetracarboxylic dianhydride from tetracarboxylates in strong acids and organic solvents. Compared with the traditional production process, the invention has high esterification reaction efficiency, prolongs the service life of the catalyst, realizes continuous production of hydrogenation reaction, and shortens the process route. The method has the advantages of simple operation, high production efficiency and low cost. The metal ion (sodium, potassium, iron, calcium, aluminum, zinc) content in the obtained 1,2,4,5-cyclohexanetetracarboxylic dianhydride is ≤1ppm, which meets the requirements of electronic grade products.

Description

technical field [0001] The invention belongs to the field of synthesis, and mainly relates to a preparation method of 1,2,4,5-cyclohexanetetracarboxylic dianhydride, specifically a method that can improve production efficiency, prolong catalyst life and improve its activity, and reduce operation process method. Background technique [0002] 1,2,4,5-Cyclohexanetetracarboxylic dianhydride is the key raw material for the synthesis of colorless and transparent polyimide, and the polyimide prepared with diamine monomer not only has excellent transparency, but also has relatively High heat resistance, high glass transition temperature, low dielectric constant, low moisture absorption and good adhesion to metals, etc., can be widely used in high-tech fields such as microelectronics, optoelectronics and aerospace. For example: in the electronic field, it is used as the substrate of liquid crystal display, the substrate of organic electroluminescent display, liquid crystal alignment...

AI Technical Summary

Problems solved by technology

Chinese patent 1428324 adopts rhodium charcoal catalytic hydrogenation pyromellitic acid to obtain better effect, but catalyst consumption is bigger (rhodium metal consumption: 1% of raw material compound weight), and rhodium charcoal is expensive, and the initial stage of catalyzer during industrialization The burden of investment has increased

This method has avoided the use of acid catalyst in the esterification reaction, has improved the preparation efficiency of hydrogenation pyromellitic acid ester simultaneously, but its hydrogenation reaction required pressure is higher (more than 10Mpa), and reaction condition is harsh, is unfavorable for large-scale Production

Chinese patent 104926649 uses solid acid H-type mordenite to replace the concentrated sulfuric acid in the esterification reaction and hydrolysis reaction. Although it avoids the influence of sulfur on the catalyst and improves the life of the fixed bed catalyst, the process route is long and the operation process is cumbersome. Low production efficiency

Chinese patent 2011103324954 uses fixed bed hydrogenation to prepare hydrogenated pyromellitic acid esters and obtains excellent results. The catalyst can run continuously for more than 1000 hours, but the carrier of the catalyst used is relatively special and needs to be self-made, which increases the manufacturing cost of the catalyst, and The reaction pressure is about 6Mpa, which is relatively high

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