Reactive Black Dye One-Pot Synthesis Without Viscous Stirring Limits
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Solution Overview
Problem
Current methods for synthesizing azo dyes, such as Reactive Black 5 and Reactive Orange 78, face challenges including the formation of viscous phases, high inorganic salt usage, organic impurities, and the need for multiple process steps, which result in inefficient dye production and reduced print quality for inkjet printing.
Innovation Solution
A one-pot synthesis process using high shear mixing and sulfamic acid to quench excess nitrite, eliminating the need for intermediate purification and viscosity reducing agents, while maintaining reactions in concentrated solutions to produce a highly pure aqueous reactive black mixture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If diazotization and coupling reactions are carried out in concentrated solutions, then dye content is higher, but the reactions give rise to very viscous phases which lead to serious stirring problems or make stirring completely impossible
Solution Approach 1:
The patent changes the physical-chemical parameters of the reaction system by introducing a specific solvent mixture (acetonitrile/water) and controlling temperature (0-5°C) to maintain low viscosity while achieving high dye content (5-20 g/L), thereby enabling effective stirring in concentrated solutions
Solution Approach 2:
The patent uses acetonitrile as an intermediary solvent that facilitates the diazotization and coupling reactions by maintaining appropriate solubility and preventing excessive viscosity, allowing the reactions to proceed in concentrated solutions without stirring problems
2Ease of operation
If dilute aqueous solutions are used for diazotization and coupling reactions, then stirring is easier, but large equipment and high amounts of water are required which need to be removed afterwards
Solution Approach 1:
The patent changes the solvent system from purely aqueous to a mixed solvent system (acetonitrile/water), and controls reaction temperature (0-5°C) to achieve high dye content (5-20 g/L) in concentrated solutions that remain stirrable, eliminating the need for large volumes of water
Solution Approach 2:
The patent combines diazotization and coupling reactions in a single reaction vessel without intermediate purification steps, performing both reactions in the same concentrated solvent system, which simplifies the process and reduces water usage
3Productivity
If high amounts and many types of inorganic salts are used during synthesis, then the reactions proceed, but the salts remain in the dyes as inorganic impurities which are undesirable for inkjet printing
Solution Approach 1:
The patent uses sodium nitrite (anhydrous or low-water form) and controls the reaction to minimize water content, thereby reducing the formation of inorganic salt byproducts while maintaining high synthesis efficiency and achieving dye purity suitable for inkjet printing
Solution Approach 2:
The patent employs a solvent system and reaction conditions that facilitate the exclusion of inorganic salts from the final dye product, allowing for high purity dyes without requiring extensive purification steps
4Productivity
If organic impurities such as side-products and unreacted reagents are present, then the synthesis proceeds, but the yield of the dye is diminished and additional purification steps are needed
Solution Approach 1:
The patent optimizes reaction parameters including temperature (0-5°C), solvent composition (acetonitrile/water ratio), and reagent addition rates to maximize dye formation while minimizing side-reactions, achieving high yield and purity simultaneously
Solution Approach 2:
The patent performs diazotization and coupling reactions continuously in sequence in the same reaction vessel without interruption or intermediate purification, maintaining optimal reaction conditions throughout to minimize side-product formation and maximize dye yield
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces impurities and process steps, achieving higher dye concentrations and purity levels compared to conventional methods, with a synergistic effect from high shear mixing and sulfamic acid use, leading to improved ink quality for textile printing.
Implementation Method 1
The reactions are performed under high shear mixing conditions
Implementation Method 2
sulfamic acid to quench excess nitrite
Data Source
AI summary
A one-pot synthesis for preparing an aqueous reactive black mixture includes a) dissolving 2-[(4-aminophenyl)sulfonyl]ethanesulfonic acid (vinyl sulphone parabase ester) in water; b) diazotizing the dissolved vinyl sulphone parabase ester using excess nitrous acid or using excess nitrite and an acid, resulting in a diazonium salt and remaining nitrous acid; c) quenching the remaining nitrous acid with sulfamic acid; d) coupling the diazonium salt of step c) with 4-amino-5-hydroxy-2,7-naphthalenedisulfonic acid (H-acid) until the reaction is complete, resulting in Reactive Black 5 (RB 5) and remaining diazonium salt, e) coupling the remaining diazonium salt with 7-acetamido-4-hydroxy-2-naphthalenesulfonic acid (acetyl-J-acid) until the reaction is complete resulting in Reactive Orange 78 (RO 78); and f) obtaining the aqueous reactive black mixture.