Continuous-Flow Synthesis of the Azo Pigment Yellow 14 Using a Three-Stream Micromixing Process

Abstract

In this study, a continuous-flow synthesis of the azo pigment Yellow 14 protocol has been developed using a three-stream micromixing process. This method controlled the pH of the azo coupling reaction process accurately and conveniently. After the optimization of the reaction conditions, the pigment products had a high purity and a good chromatic light. Compared with the two-stream micromixing process, the purity of the pigment products synthesized by the three-stream micromixing process increased by 9.41%, and the color differences between pigment products and Yellow 14 standard decreased obviously. Furthermore, the transparency numbers of pigment products synthesized by the microreactor system increased by 93−99% compared with that of the Yellow 14 standard. For the chromatic light, the red and blue hues of the pigment products were more intense than those of the Yellow 14 standard. Overall, the three-stream micromixing process led to an improvement of the pigment products, and this method also has good potential in industrial applications.

Revisiting aromatic diazotization and aryl diazonium salts in continuous flow: highlighted research during 2001–2021

“…7). 83,84 Their work shows that reducing the mass transfer distance, increasing the flow rate and improving the concentration distribution are important means of enhancing the mass transfer, and port improvement in the micromixer can prevent clogging.…”

“…67 In this system, the CFU unit is once again used to achieve precise control of the stoichiometry of aryl azide. Malononitrile (82), 1,3-cyclohexanedione (83) and alkyne (84) were used to react with aryl azide to form 1-aryl-[1,2,3]-triazole derivatives in continuous flow, in which good yields were obtained regardless of whether the substrate was an electron-donating aniline or an electron-deficient aniline. This system can realize the rapid assembly of various triazole derivatives because of the automatic operation and precise parameter control of the CFU.…”

Microwave-assisted rapid and sustainable synthesis of unsymmetrical azo dyes by coupling of nitroarenes with aniline derivatives

“…In recent times, the stringent environmental concerns have instigated the development of various alternative and greener strategies for the synthesis of azo dyes that include diazo coupling on clay, polymer, or resin-supported diazonium salts ( Caldarelli et al., 2000 ; Merrington et al., 2002 ; Dabbagh et al., 2008 ; Kollarigowda and Braun, 2021 ), and use of grindstone chemistry ( Eissa and Mohamed, 2018 ). Besides, a few continuous flow methods are also developed for diazo coupling ( Wang et al., 2019 ; Shukla et al., 2021 ). Although these methods click several greener aspects, the concerns on stability of diazonium salts or substrate limitation are always associated with diazo coupling.…”

Modification of C.I. Pigment Red 146 with surfactants and graphene oxide

“…146, the mean particle size can be significantly reduced. 13 In addition, the lightness and green and blue hues can be enhanced compared to those of standard P.R. 146.…”