Chemical Properties
black fine crystalline powder
Uses
Eriochrome is to do titration indicator. Dubbed in aqueous solution or alcohol-soluble when used for the determination of calcium, magnesium, manganese, zinc and other metal ions, measured water hardness.
Preparation
4-Amino-3-hydroxynaphthalene-1-sulfonic acid diazotization, and Naphthalen-1-ol coupling.
Purification Methods
Free it from metallic impurities by three precipitations from aqueous solution by addition of HCl. The precipitated dye is dried at 60o under vacuum and converted into the Na salt with the calculated amount of alkali. It is an indicator in the complexometry of Al, Fe and Zr. [Beilstein 16 III 319.]
Properties and Applications
blue light grey to blue black. Soluble in water is purple, soluble in ethanol (in red), Acetone, insoluble in Toluene. In concentrated sulfuric acid for skipper, after dilution for shallow sauce red; In concentrated nitric acid for yellow solution. Dye aqueous solution to join concentrated hydrochloric acid for pale red light brown; Join concentrated sodium hydroxide solution for red wine.
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Standard
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Ironing Fastness
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Light Fastness
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Fulling
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Persperation Fastness
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Soaping
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Water
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Alkali
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Acid
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ISO
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4-5
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6
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4-5
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4
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5
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5
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5
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AATCC
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4
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6
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4-5
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5
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5
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5
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