Hazard
Moderately toxic. Low toxicity by ingestion.
Chemical Properties
Gray to black powder. Black when dissolved in water, reddish purple in concentrated sulfuric acid, and produces a black-purple precipitate after dilution. Black precipitate in concentrated hydrochloric acid and dark purple precipitate in concentrated caustic soda solution.
Uses
C.I. Direct black 32 is a good dyeing agent for cotton fabrics.
Preparation
5-Amino-2-(4-aminophenylamino)benzenesulfonic acid double nitriding, in alkaline conditions and 6-Amino-4-hydroxynaphthalene-2-sulfonic acid? (2 Moore) coupled, product to double nitriding, and 2-(3-Aminophenylamino)ethanol (2 Moore) coupled.
Properties and Applications
black. Grey to black powder. The strong sulfuric acid for red purple, after dilute black purple precipitation; In strong hydrochloric acid in black precipitation; In the thick of sodium hydroxide solution dark purple precipitation. Mainly used for cotton, such as glue cellulose fiber fabric and silk dyeing and printing. Used for sweet silk and viscose interwoven fabric dyeing.
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Standard
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Acid Resistance
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Alkali Resistance
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Light Fastness
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Soaping
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Water
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Fading
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Stain
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Fading
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Stain
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ISO
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4
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4
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4
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3-4
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4
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References
[1] Sawada K, Ueda M. Adsorption behavior of direct dye on cotton in non-aqueous media[J]. Dyes and pigments, 2003, 58(1): 37-40.