Method for producing 5-amino-6-methyl benzimidazolone

Abstract

The invention discloses a method for producing 5-amino-6-methyl benzimidazolone. The method is characterized by sequentially comprising the following steps that 1, 3,4- diaminotoluene and urea are circulated in a solvent, then a condensation reaction is carried out, and 5-methyl benzimidazolone is obtained; 2, 5-methyl benzimidazolone is nitrated, and 5-nitryl-6-methyl benzimidazolone is obtained;3, 5-nitryl-6-methyl benzimidazolone is reduced, and the target compound 5-amino-6-methyl benzimidazolone is obtained. According to the method, the condensation temperature in the first step ranges from 120 DEG C to 140 DEG C. Tail gas generated in the reaction process of the first step is introduced into a boiler furnace to be incinerated. According to the method, a 1,2-xylene, ethylbenzene, 1,3-xylene, 1,4-xylene and mixed xylene system is adopted for condensation, the yield reaches up to 99%, and higher environmental friendliness is achieved. Ammonia nitrogen in waste water can be greatlyreduced. The yield of condensation, nitration and reduction is much higher than those of other methods, and the comprehensive yield ranges from reaches 90% to 92%.

Description

technical field [0001] The invention belongs to the technical field of compound preparation methods, and in particular relates to a preparation method of a fine chemical intermediate. Background technique [0002] 5-Amino-6-methylbenzimidazolone is an important pigment intermediate used in the synthesis of Pigment Orange 64. It is currently produced by BASF (formerly Ciba Specialty Chemicals) in Germany, but the technology has not been disclosed. The current location can be found There are relatively few documents, and even if there are some documents, they are all documents of some laboratory experiments, and there is no specific technical introduction of industrial production. The relevant documents that can be found are: CN1675185, this patent introduces the synthesis method of 5-amino-6-methylbenzimidazolone, which first carries out cyclization in amyl alcohol, and then nitration reduction, the product yield is very low; US The 6087480 patent uses 5-nitro-6-methylbenzim...

AI Technical Summary

Problems solved by technology

[0002] 5-Amino-6-methylbenzimidazolone is an important pigment intermediate used in the synthesis of Pigment Orange 64. It is currently produced by BASF (formerly Ciba Specialty Chemicals) in Germany, but the technology has not been disclosed. The current location can be found There are relatively few documents, even if there are some documents, they are all documents of laboratory experiments, and there is no specific technical introduction of industrial production

The relevant documents that can be found are: CN1675185, this patent introduces the synthesis method of 5-amino-6-methylbenzimidazolone, which first carries out cyclization in amyl alcohol, and then nitration reduction, the product yield is very low; US The 6087480 patent uses 5-nitro-6-methylbenzimidazolone as a raw material for reduction, but this raw material is not available in the market, so it can only be synthesized by itself, and no specific synthesis method is introduced; CN101863840A introduces more specifically The synthesis method of 5-amino-6-methylbenzimidazolone, but it adopts the laboratory method, and the cyclization yield is 98.5%; dilute nitric acid is used for nitration during nitration in the process, and a large amount of nitric acid waste water is produced, which is difficult to handle; reduction The method can only obtain a higher yield of 91.8% by palladium-carbon hydrogenation reduction, and use DMF as a solvent, which must be recovered by vacuum distillation