A method for preparing 4,4'-diaminodiphenyl ether

Abstract

The invention discloses a 4, 4'-diamino-diphenyl ether preparing method and relates to the technical field of preparation of fine chemical engineering organic materials. The method comprises the following steps of (1) adding 4, 4'-dinitro-diphenyl ether, Pd / C catalyst, mixed solvent of benzene-ring solvent and water, and antioxidant in a hydrogenation reactor, performing mixing, inletting hydrogen and increasing the temperature for catalyzed hydrogenation reaction; (2) after the catalyzed hydrogenation reaction is completed, transmitting the reacted materials into a glycol biological solvent, increasing the temperature to dissolve 4, 4'-diamino-diphenyl ether obtained through reaction, performing hot filtration, recovering the Pd / C catalyst, cooling and crystallizing filter liquor, separating solids and liquids, drying the solids to obtain the 4, 4'-diamino-diphenyl ether. The 4, 4'-diamino-diphenyl ether preparing method is short in process, low in energy consumption and simple in operation, can produce high-quality white 4, 4'-diamino-diphenyl ether crystals without sublimation and achieve a content higher than 99.8% and a recovery rate higher than 90%, thereby being applicable to industrial production.

Description

technical field [0001] The invention relates to the technical field of preparation of fine chemical organic materials. Background technique [0002] 4,4'-diaminodiphenyl ether is an important monomer for the synthesis of polyimide, which can be polymerized with various dianhydrides to form polyimide. Polyimide is the super heat-resistant resin with the highest heat-resistant temperature so far , and has excellent hydrolysis resistance, mechanical properties and flexibility, and can be widely used in the production of heat-resistant resin moldings, electrical insulation films, etc. [0003] At present, the main preparation methods of 4,4'-diaminodiphenyl ether include iron powder reduction method, hydrazine hydrate reduction method and catalytic hydrogenation reduction method. The iron powder reduction method has a simple process, but the content of the obtained product is relatively poor, and a large amount of wastewater is produced. The wastewater contains aromatic amines,...

AI Technical Summary

Problems solved by technology

The disadvantage of the current catalytic hydrogenation reduction method is that the 4,4’-diaminodiphenyl ether obtained by the reaction is very easy to change color. After being separated from the solvent, it has to be refined by energy-intensive and artificial sublimation methods or recrystallization, and the operating cost is high.

Common solvents for nitro hydrogenation such as alcohols, N,N-dimethylformamide, N,N-dimethylacetamide, when used for catalytic hydrogenation of 4,4'-dinitrodiphenyl ether, these solvents The solubility of 4,4'-diaminodiphenyl ether varies little with temperature, and the 4,4'-diaminodiphenyl ether formed after the reaction cannot be crystallized smoothly by taking advantage of the difference in solubility at different temperatures, so it must be concentrated If these methods are used in production, the process will be too long, and the 4,4'-diaminodiphenyl ether will be heated for a long time, which will cause 4,4'-diaminodiphenyl ether to change during the process. Yellow or even black, it must be sublimated to be purified; for example, CN103044276, CN102850229, CN101468952, and CN1827586 all used catalytic hydrogenation to prepare 4,4'-diaminodiphenyl ether, but the 4,4'-diphenyl ether obtained after the reaction was completed Diaminodiphenyl ether needs to be sublimated or recrystallized again to obtain higher quality products, which is difficult to operate and high in production cost.