Method for preparing 4,4-methylenedianiline

Abstract

The invention discloses a method for preparing 4,4'-methylenedianiline, which comprises the following steps of: 1) adding phenylamine and formaldehyde in a molar ratio of 10:1-2:1 into a reactor with a reflux device, adding an organic solvent and a solid acid catalyst, ensuring that a weight ratio of the solid acid catalyst to the formaldehyde is 1:50:1-2:1, reacting at the temperature of between 70 and 110DEG C for 20 to 70 minutes with stirring under the protection of inert gas, and performing microwave treatment with the power of 100-600 watts during the reaction; 2) performing centrifugal separation on the catalyst and reaction liquid, and performing vacuum rectification on the reaction liquid to obtain a solid product; and 3) dissolving the rectified solid product by using ethanol, and recrystallizing to obtain 4,4'-methylenedianiline. In the method for preparing the 4,4'-methylenedianiline, the 4,4'-methylenedianiline is directly synthesized by the phenylamine and the formaldehyde in the presence of the catalyst under the microwave condition, reaction activity is high, the target product has selectivity and recycling activity, and by the microwave reaction condition, energy consumption is reduced, reaction time is shortened, reaction yield is improved and the reaction economy is improved.

Description

technical field [0001] The present invention relates to a kind of preparation method of 4,4'-diaminodiphenylmethane. Background technique [0002] 4,4'-Diaminodiphenylmethane is an important chemical intermediate, mainly used in the production of diisocyanate compounds, and also used in the preparation of high-grade insulating materials such as bisma resin, polyimide, polyesterimide, etc. And polyurethane elastomer chain extender, epoxy resin curing agent, polymer crosslinking agent, etc. The above-mentioned various products synthesized with 4,4'-diaminodiphenylmethane have excellent heat resistance, insulation, mechanical properties and wear resistance, etc., and are a kind of fine chemical products with wide application and excellent performance. [0003] At present, the main synthesis process of 4,4'-diaminodiphenylmethane is to condense aniline and formaldehyde at high temperature under acid catalysis to prepare a mixture of diaminodiphenylmethane compounds. Under diff...

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Problems solved by technology

Using ordinary liquid acid as a catalyst, high-temperature condensation of aniline and formaldehyde can only obtain part of 4,4'-diaminodiphenylmethane, and there are problems such as strong acid corrosion to equipment, relatively difficult post-processing, and high energy consumption.

There are foreign patents that use clay, zeolite, diatomaceous earth, etc. as solid acid catalysts, which eliminates the relatively complicated post-treatment problems such as corrosion of liquid acid and neutralization, but there are problems such as complicated pre-treatment and complex products.

Chinese patents CN1676498 and CN 101007767 use molecular sieves, phosphotungstic acid, and loaded phosphotungstic acid as solid acid catalysts, which simplifies the post-treatment process and improves the selectivity and yield of the target product. High temperature, high energy consumption, and low catalyst recycling rate

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