Indole producing process

Abstract

The present invention relates to coal chemical technology, and is indole producing process. The residual oil from beta-methylnaphthalene and containing indole in about 30 % is used as material for producing indole through azeotropic rectification and washing crystallization. The production process includes azeotropic rectification to obtain indole fraction, water washing to eliminate azeotrope agent, re-crystallization in solvent and centrifuging to obtain indole product with content over 99 %.

Description

technical field [0001] The invention relates to the technical field of coal chemical industry, and relates to a method for producing indole. Background technique [0002] Indole is mainly used in agricultural chemistry, spices, medicine and dyes, such as the synthesis of plant growth hormones such as β-indole acetic acid; the synthesis of tryptophan is an amino acid necessary for animal growth, and can also be used as an anti-deficiency protein disease Gastric ulcer medicine, used as a fragrance retainer in the production of spices. [0003] The content of indole in coal tar is 0.1-0.2%, and it is mainly concentrated in the washing oil fraction. In our factory, it is mainly distributed in industrial methyl naphthalene, and the content is about 4%-6%. In the process of producing β-methylnaphthalene, we found that its residual oil contains about 30% indole, which is much higher than the indole content in industrial methylnaphthalene, creating condi...

AI Technical Summary

Problems solved by technology

Solvent extraction is a relatively mature method for recovering indole, but the selectivity of the currently used extractant is still not ideal, resulting in the loss of the target product. At the same time, a large amount of solvent must be recovered for recycling, resulting in high production costs, especially in raw materials. The disadvantages are particularly prominent when the content of indole is low

[0007] 3. Acid polymerization method: use strong acid to react with indole in the washing oil to form indole low polymer, then deacidify, decompose the polymer, and refine indole again. The most prominent feature of this method is the indole content in the raw material In the lower case, the yield is relatively high, but this method is complicated, and the acid tar produced by strong acid is difficult to handle

[0008] 4. Adsorption method: use zeolite to adsorb and then desorb the indole fraction. This method has only been used in the laboratory and does not have the conditions for industrialization

[0015] The conclusions are as follows: the new product indole developed by the entrusting unit with the above novelty check points has not been reported in the relevant domestic literature