Aurin

Aurin
Names
IUPAC name
4-[Bis(p-hydroxyphenyl)methylene]-2,5-cyclohexadien-1-one
Other names
Aurin, corallin, p-rosolic acid, C.I. 43800
Identifiers
3D model (JSmol)
2055205
ChemSpider
ECHA InfoCard 100.009.129
EC Number 210-041-8
Properties
C19H14O3
Molar mass 290.32 g·mol−1
Appearance see text
Density 1.283 g/cm3
Melting point 308 °C (586 °F; 581 K) (decomposes)
Insoluble
UV-vis (λmax) 482 nm[1]
-161.4·10−6 cm3/mol
Hazards
GHS pictograms [1]
GHS signal word Danger
H315, H319, H335[1]
P261, P305+351+338[1]
NFPA 704
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g., canola oil Health code 1: Exposure would cause irritation but only minor residual injury. E.g., turpentine Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
1
1
0
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Aurin (C.I. 43800), sometimes named rosolic acid or corallin is an organic compound, forming yellowish or deep-red crystals with greenish metallic luster. It is practically insoluble in water, freely soluble in alcohol. It is soluble in strong acids to form yellow solution, or in aqueous alkalis to form carmine red solutions.

Aurin (pH indicator)
below pH 5.0 above pH 6.8
5.0 ⇌ 6.8

Due to this behaviour it can be used as pH indicator with pH transition range 5.0 - 6.8. It used as intermediate in manufacturing of dyes.

Synthesis

Aurin is formed by heating of phenol and oxalic acid in concentrated sulfuric acid.

Safety

Causes eye, skin, and respiratory tract irritation. Avoid ingestion and/ or inhalation.

References

  1. 1 2 3 4 Sigma-Aldrich Co., p-Rosolic acid. Retrieved on 2014-05-06.
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