Dye continuous diazotization process

Abstract

The invention discloses a dye continuous diazotization process. The process comprises the following steps: (1) adding a diazonium liquid as a bottom liquid to a mixing pot, then adding aromatic amine to conduct mixing dispersion to obtain a mixture; (2) respectively and continuously inputting the mixture and nitrosyl sulfuric acid into multiple stages of series loop reactors for a diazotization reaction to obtain a reaction liquid; inputting the mixture from the inlet of a first stage of loop reactor, inputting nitrosyl sulfuric acid from the inlet of each stage of loop reactor, and outputting the reaction liquid from the outlet of a final stage of a loop reactor; and (3) detecting the reaction liquid in a center control detection reaction pot; if the diazotization reaction is complete, sending the reaction liquid directly into a diazonium liquid product groove; and if the diazotization reaction is not complete, continuing the reaction in a center control reaction reactor. The diazotization process employs an outer circulation heat exchanger to achieve effective temperature control effect, improve the stability, uniformity and controllability of diazotization reaction, and improve the quality of dye products.

Description

technical field [0001] The invention belongs to the field of dye synthesis, and in particular relates to a continuous diazotization process of dyes. Background technique [0002] In the diazotization reaction of dye synthesis, under normal circumstances, aromatic amine raw materials are reacted with sodium nitrite in the presence of inorganic acids, and the product diazonium salt produced by the reaction is an important intermediate for azo compounds. This diazotization reaction is widely used in organic synthesis processes such as medicines, pesticides, and dyes, especially in the dye industry, where more than 60% of dyes are produced through diazotization reactions. [0003] At present, the diazonium salt synthesis methods adopted by dyestuff enterprises are basically batch processes, which are mainly cis-feeding method and reverse-feeding method, cis-feeding method such as sodium nitrite added dropwise to the inorganic acid Diazotization is carried out in solution or sus...

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Problems solved by technology

[0006] A common problem in these patents is that a large amount of sulfuric acid is used to dissolve aromatic amine raw materials, so that a large amount of low-concentration inorganic acids will be produced in subsequent production, and the cost of environmental protection is relatively high; The change is more sensitive, and often need to use a lot of cooling facilities, such as adding coils in the reaction pot and cooling the outer jacket of the pot at the same time to control the reaction efficiency. , so the effect is still not ideal

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