Method for synthesizing o-phenylenediamine from ortho-nitroaniline by virtue of catalytic hydrogenation

Abstract

The invention provides a method for synthesizing o-phenylenediamine from ortho-nitroaniline by virtue of catalytic hydrogenation. The method comprises the following steps: firstly, adding ortho-nitroaniline and a palladium-carbon catalyst into a high-pressure reaction kettle, introducing nitrogen to exhaust air in the kettle, and then introducing hydrogen to exhaust nitrogen in the kettle; secondly, heating and introducing hydrogen, performing catalytic hydrogenation reduction reaction under the conditions that the temperature is 110 DEG C and the pressure is 1.0MPa, reacting for 7-8 hours, then stopping introducing hydrogen, water-cooling, then filtering to recycle the catalyst, and collecting a filtrate after filtration to obtain o-phenylenediamine. According to the method provided by the invention, a raw material namely ortho-nitroaniline is subjected to direct hydrogenation without using a solvent, so that the consumption of the solvent can be greatly reduced, the after-treatment energy consumption can be saved, and large-sized solvent steaming equipment can be saved; and by adopting the method, a separation process can be simplified, the equipment investment, separation energy consumption, material consumption and environmental pollution can be reduced, and the system productivity and production safety can be improved.

Description

technical field [0001] The invention belongs to the technical field of catalytic hydrogenation, and in particular relates to a method for synthesizing o-phenylenediamine by catalytic hydrogenation of o-nitroaniline. Background technique [0002] O-phenylenediamine is an important chemical intermediate, mainly used in the synthesis of pesticides, dyes, auxiliaries, photosensitive materials, etc., and has a wide range of uses and broad market prospects. Its synthesis process includes vulcanization method, ammoniation method and catalytic hydrogenation method, etc. Catalytic hydrogenation method generally produces products and water, and does not generate other by-products (except for side reactions), so it has a good development prospect. [0003] The method of producing o-phenylenediamine mainly contains following several at present: (1) chemical reduction method; (2) electrolytic reduction method; (3) palladium charcoal catalytic hydrogenation reduction method. Among them, ...

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Problems solved by technology

The palladium-carbon hydrogenation reduction method has the characteristics of good product quality and less waste generation. However, the traditional process generally uses methanol as a solvent. Not only does the large amount of solvent use increase the production cost, but also the solvent needs to be evaporated with the help of large-scale equipment during post-treatment. Therefore, The energy consumption of post-treatment process increases, equipment investment, separation energy consumption, material consumption and environmental pollution increase, which will affect the system capacity and production safety

[0004] Up to now, no solvent-free preparation of o-phenylenediamine has been reported.

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