Preparation method and application of 4,4'-diphenylamine

Background and overview

As a special engineering material, polyimide has the advantages of high temperature resistance, radiation resistance and high mechanical strength. It is used in films, coatings, fibers, aerospace, electronic and electrical industries, foamed plastics and photoresists. 4,4'-Diaminodiphenyl ether is one of the main raw materials. At the same time, 4,4'-diaminodiphenyl ether can also be used to produce cross-linking agent, and is widely used to replace carcinogenic benzidine to produce azo dyes and reactive dyes. Therefore, 4,4'-diaminodiphenyl ether is an intermediate with high added value.

Preparation

800 g of dimethylformamide, 165g (0.63 mol) of 4,4'-dinitrodiphenyl ether, and 16.5 g of activated carbon were sequentially placed in a reaction vessel, adsorbed by activated carbon, and heated to 140 °C for 2 hours. After that, filter it hot. The mother liquor was filtered into a hydrogenation vessel, and 1g of a palladium carbon catalyst having a palladium content of 5% by weight was placed in a hydrogenation reactor, and then the temperature was raised to 140 °C, and hydrogen was continuously supplied. The gas is maintained at a pressure of 1MPa, hydrogenated for 5 hours, until the content of 4,4'-diaminodiphenyl ether is above 99.9% by weight, cooled to 70 ° C, and hydrogenation is carried out into the crystallizer with nitrogen gas, and 200 g of the first in the crystallizer is added. Toluene and 800g water, Stirring at 30-50 rpm for 8 hours, recrystallization, centrifugation, and the resulting precipitate was washed with 400 ml of methanol, dried, and dried to obtain a product.4,4'-diaminodiphenyl ether, weight 125 g, yield 99.5%

Use

Can be used to prepare 4,4'-dihydroxydiphenyl ether

With a volume of 200ml, a thermometer,100 ml of sulfuric acid having a concentration of 20% by mass was placed in an eggplant type flask equipped with a magnetic stirrer, 10g(0.05mol) of 4,4'-diaminodiphenyl ether was added while stirring, The liquid temperature was cooled to 0°C.7.2g(0.105mol) of sodium nitrite was added little by little while maintaining the same temperature to obtain a reaction solution of diazonium salt. Meanwhile, with a volume of 500 ml, a thermometer, a magnetic stirrer, And a flask equipped with a dropping funnel, 200 ml of 20 mass% sulfuric acid,100 ml of nitrobenzene was charged, and the temperature was maintained at 130 ° C. Here, the previously prepared diazonium salt reaction solution was added over 30 minutes, Thereafter, it was aged at the same temperature for 10 minutes, A hydrolysis reaction of the diazonium salt was carried out. After completion of the reaction, the organic phase of the lower phase was recovered by liquid separation, It was extracted with 170 g of a 5% potassium hydroxide aqueous solution, The aqueous phase was washed twice with 50 ml of toluene. Finally, the aqueous phase was acidified with hydrochloric acid and the precipitated solid was collected by filtration, washed with water, And dried to obtain 8.2 g (yield 81.2%) of 4,4'-dihydroxydiphenyl ether.

It is used to make heat-resistant plastics such as polyimide resin, polymaleimide resin, polyamideimide resin, polyesterimide resin, epoxy resin, polyurethane, etc. It is also used as a crosslinking agent. Also used as a curing agent for epoxy resins, the cured product has high thermal deformation temperature, good thermal stability, excellent chemical resistance and water resistance. At the same time, it can be used as a curing agent for epoxy resin. The cured product has high thermal deformation temperature, good thermal stability, excellent chemical resistance and water resistance. It is also the raw material of heat-resistant plastic polyamide-imide resin, polyester-imide resin, polyimide resin, polymaleimide resin, etc.

References

【1】CN108276297,2018, A

【2】JP2015/51964,2015, A