Method for extracting nitration product from N-ethyl carbazole nitration solvent distillation residue

Abstract

The invention discloses a method for extracting a nitration product from N-ethyl carbazole nitration solvent distillation residue. The method is characterized by comprising the following steps of: putting the N-ethyl carbazole nitration solvent distillation residue and an organic solvent in a container, heating while stirring to a reflux state, stirring for 0.5-6 hours while preserving heat, adding a flocculant and continuing stirring for 0.5-6 hours while preserving heat, and then filtering while the solution is hot or taking out the supernatant liquid from the container after standing, thereby obtaining 3-nitro-N-ethyl carbazole solution; and in order to improve the quality of the 3-nitro-N-ethyl carbazole solution, further adding active carbon to the solution for absorption bleaching, and after stirring for 0.5-6 hours while preserving heat, filtering while the solution is hot, thereby obtaining the solution of 3-nitro-N-ethyl carbazole. The method for extracting the nitration product from N-ethyl carbazole nitration solvent distillation residue has the advantages that the extraction process is simple and high in efficiency, the yield of permanent violet nitration is greatly improved and further the total yield of permanent violet synthesis is improved, the production cost of permanent violet is reduced, the waste residue is reduced and the environmental protection effect is good.

Description

technical field [0001] The invention relates to a method for extracting nitration products from distillation residue of N-ethylcarbazole nitration solvent. Background technique [0002] Permanent Violet RL generally uses carbazole as the starting material, reacts with ethyl bromide in the presence of a phase transfer catalyst to generate N-ethyl carbazole (95%), and then nitrates with dilute nitric acid to obtain 3-nitro- N-Ethylcarbazole (75%), and then reduced by alkali sulfide or hydrogenation to obtain 3-amino-N-ethylcarbazole (95%), which is condensed and closed with tetrachlorobenzoquinone to obtain the crude product of permanent purple (90%), finally obtained by pigmentation (99%). [0003] From the yield of each step in the synthetic process of permanent violet RL, it is obvious that the key step that affects the total yield of the synthesis lies in the nitration reaction of N-ethylcarbazole, and improving the yield of this step can greatly improve Total yield of e...

AI Technical Summary

Problems solved by technology

[0004] For the analysis of the nitration reaction of N-ethylcarbazole, the reason for the low yield of this step reaction is: the reaction is not complete, and a very small amount of N-ethylcarbazole does not participate in the reaction; a small amount of isomer 1-nitro-N- The generation of ethyl carbazole, excessive nitration to generate 3,6-dinitro-N-ethyl carbazole, 1,6-dinitro-N-ethyl carbazole; after the reaction, some products stay in the reaction solvent middle