Method for synthesizing 3,5-diamido benzoic acid by industrial continuous hydrogenation

Abstract

The invention discloses an industrial continuous hydrogenation method for synthesizing 3,5-diaminobenzoic acid. Using m-dinitrobenzoic acid and hydrogen as raw materials and water as a reaction solvent, water and a catalyst are added to a reduction kettle. In addition, the raw materials m-dinitrobenzoic acid and hydrogen are respectively added to carry out the reduction reaction; the reaction solution continues to react in the second and third reduction kettles until the conversion rate reaches 100%, and then the reaction solution is crystallized to obtain the product. The present invention uses three successively connected reduction kettles to complete the reduction reaction. The contact time of the raw materials is long, and the conversion rate of the raw materials can reach 100%. More than 97%.

Description

Technical field [0001] The present invention involves a method of preparing a 3,5-dilatelybenzoic acid, which specifically involves a method of industrialized continuous hydrogen hydrogenation of 3,5-dilate phenyl acid, which is a technical field of organic synthetic chemistry. Background technique [0002] 3,5-dihydonzolic acid is an important type of dye. Medicine intermediates, with it as raw materials, can develop many high value-added downstream products.A series of yellow -active dyes derived from it can be used as a dark yellow dye, or it can also be used as a yellow component in black dyes. The current market demand is large.3,5-diodes are generally obtained by the reaction of 3,5-diitrocytybenzoic acid as the raw material.The literature involves 3,5-di-nitrate phenolic acid reduction and preparing 3,5-dilate phenyl acid:: Iron powder restoration, pupae restore and hydrogenation reduction three routes.The use of iron powder reduction method to produce 3,5-dilate phenyl ac...

AI Technical Summary

Problems solved by technology

Although it is recorded in the description that the product purity is as high as 95%, and the yield is as high as more than 96%, there is no sufficient record in the examples of this patent on the use of activated carbon catalysts to prepare the relevant data of m-diaminobenzoic acid, and the description does not disclose this technology. The detailed substantive content of the scheme, and the method recorded in this patent is only in the small test stage and is not suitable for industrialized large-scale production

In addition, this patent also has the following deficiencies: 1. The batch production process is adopted, and the operation procedure is cumbersome, and the operator must be on site at all times, so there are human safety hazards, and the batch production needs to be replaced every time, and the replacement needs to consume a certain amount of nitrogen and hydrogen. , and part of the solvent will be brought into the air, resulting in pollution; 2. The use of organic solvents such as methanol or ethanol, which are extremely volatile, flammable and explosive solvents, have certain pollution to the air or surface water, and the product purity and yield relatively low

The compatibility of this material with organic solvents (methanol or ethanol) is not good, and it cannot be completely dissolved, and this material is acidic, with a pH of about 1-3, which affects the activity of nickel-based catalysts. Realize industrial production

If the pH is adjusted to make the material into a salt, it will be almost insoluble with organic solvents, and the reaction situation cannot be verified.

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