Skeleton nickel catalyzed 5-nitrobenzimidazole ketone reducing process for preparing 5-aminobenzimidazole ketone

Abstract

The present invention discloses skeleton nickel catalyzed 5-nitrobenzimidazole ketone reducing process for preparing 5-aminobenzimidazole ketone, and belongs to the field of 5-aminobenzimidazole ketone preparing technology. The process includes: adding Ni-Al alloy into NaOH solution at certain temperature and in certain concentration to react for certain time and washing with water and anhydrous alcohol for several times to obtain skeleton nickel maintained in anhydrous alcohol; setting skeleton nickel, 5-nitrobenzimidazole ketone and anhydrous alcohol in certain weight proportion into high pressure kettle to react at 80-120 deg.c and 1.0-6.0 MPa for 4-15 hr; filtering to eliminate catalyst, vacuum distilling, suction filtering, and vacuum drying the filter cake to obtain 5-aminobenzimidazole ketone. The present invention has the advantages of simple technological process, easy operation, low cost, product yield of 89.0-94.0 % and purity 97.0-99.8 %, and environment friendship.

Description

technical field [0001] The invention relates to a method for preparing 5-aminobenzimidazolone through catalytic reduction of 5-nitrobenzimidazolone by skeleton nickel, which belongs to the preparation technology of 5-aminobenzimidazolone. Background technique [0002] 5-Aminobenzimidazolone is an important pigment intermediate used in the preparation of high-grade organic pigments. 5-aminobenzimidazolone is usually prepared by reducing 5-nitrobenzimidazolone. The main reduction methods include iron powder reduction, hydrazine hydrate reduction and catalytic hydrogenation reduction. At present, the iron powder reduction method is mainly used in industry, the process is mature, the equipment investment is small, the price of iron powder is low, and the operation is simple, but a large amount of iron oxide sludge is produced in the process, and the post-treatment is complicated, causing serious pollution to the environment; hydrazine hydrate reduction ...

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Problems solved by technology

At present, the iron powder reduction method is mainly used in industry, the process is mature, the equipment investment is small, the price of iron powder is low, and the operation is simple, but a large amount of iron oxide sludge is produced in the process, and the post-treatment is complicated, causing serious pollution to the environment; hydrazine hydrate reduction method, low equipment investment, mild reaction conditions, good reduction effect, partial reduction can be carried out, and no waste gas and waste residue are produced, but it is only suitable for the synthesis of small batches and short-term aromatic amines, not suitable for large-scale industrial production; catalytic hydrogenation reduction method, complete reaction, few side reactions, high product quality and yield, less environmental pollution, Okujima et al. and imidazolone to prepare 5-aminobenzimidazolone, the yield is about 95%, but the catalyst is expensive, recycling is more difficult, and it is difficult to industrialized production