Acid orange 5
Appearance
Names | |
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Preferred IUPAC name
Sodium 4-[(E)-(4-anilinophenyl)diazenyl]benzene-1-sulfonate | |
Other names
Fast yellow; Tropaeolin OO
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Identifiers | |
3D model (JSmol)
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ChemSpider | |
ECHA InfoCard | 100.008.248 |
PubChem CID
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UNII | |
CompTox Dashboard (EPA)
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Properties | |
C18H14N3NaO3S | |
Molar mass | 375.38 g/mol |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Tropaeolin OO (pH indicator) | ||
below pH 1.4 | above pH 3.2 | |
1.4 | ⇌ | 3.2 |
Acid orange 5 is a compound with formula Na(C6H5NHC6H4N=NC6H4SO3). It is an azo dye. It is also used as a pH indicator; it is red in pH under 1.4, orange-yellow in pH over 3.2.[1]
Preparation
[edit]Acid orange 5 may be prepared by diazotization of sulfanilic acid, followed by reaction with diphenylamine:
- HO3SC6H4N+2 + (C6H5)2NH → HO3SC6H4N=NC6H4N(H)C6H5 + H+
References
[edit]- ^ Beilstein 16 II 171.