97794-07-5Relevant articles and documents
A quantitative one-pot synthesis method for industrial azo pigments with recyclable wastewater
Feng, Guangyuan,Zhu, Meiling,Liu, Lei,Li, Chunbao
supporting information, p. 1769 - 1776 (2019/04/08)
Most industrial azo pigments are synthesized by diazotization in one pot and then coupling in another. This two-pot process has been transformed into a one-pot method by adding granular PTFE (polytetrafluoroethylene) to a mechanically agitated aqueous mixture of NaNO2, HCl, a diazo component and a coupling component. This method avoids the step of using a base or a surfactant to dissolve the coupling component. The reactions were fast and quantitative. The granular PTFE, wastewater and excess HCl were then reused 11 times without deteriorating the reaction rate and product purity. Altogether, 22 industrial pigments and 3 azo compounds were synthesized and the reaction can produce up to 22.7 g of product in the laboratory. Some reactions require less than 2 equiv. of HCl and a mechanism explaining this is proposed. In addition, an o-nitro group effect is advanced to explain the differences in coupling reaction rates for o-, m- and p-nitroaniline.
Production process and system for insoluble azo pigments
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Page/Page column 11-12, (2008/06/13)
An insoluble azo pigment is produced by ejecting a diazo solution and a grounding solution continuously into an ejector such that within the ejector, the diazo solution and grounding solution are mixed with each other and are subjected to a coupling reaction. A production system for the insoluble azo pigment includes the following units (1) to (4): (1) a first feed tank (2) for a first fluid selected from the diazo solution or grounding solution, a first flow path (a) for feeding the first fluid to nozzles of an ejector (1), and a pump (d) for feeding the first fluid through the first flow path; (2) the ejector (1) provided with the nozzles, a suction chamber, a diffuser, and a temperature control device (g); (3) a second feed tank (3) for a second fluid, a second flow path (b) for guiding the second fluid into the suction chamber, and a flow control device (e) for controlling a flow rate of the second fluid through the second flowpath (b); and (4) a heat treatment tank (5) for subjecting to heat treatment a suspension of the insoluble azo pigment formed by a reaction between the first fluid and the second fluid, and a third flow path (a′) for guiding the suspension from the diffuser to the heat treatment tank.