Aurin

For the French commune, see Aurin, Haute-Garonne.

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

Aurin

Names
Preferred IUPAC name 4-[Bis(4-hydroxyphenyl)methylidene]cyclohexa-2,5-dien-1-one
Other names Aurin, corallin, p-rosolic acid, C.I. 43800
Identifiers
CAS Number	603-45-2 Y
3D model (JSmol)	Interactive image
Beilstein Reference	2055205
ChEMBL	ChEMBL210868 Y
ChemSpider	4921 Y
ECHA InfoCard	100.009.129
EC Number	210-041-8
PubChem CID	5100
UNII	85N4AK3JAU Y
CompTox Dashboard (EPA)	DTXSID2022387
InChI InChI=1S/C19H14O3/c20-16-7-1-13(2-8-16)19(14-3-9-17(21)10-4-14)15-5-11-18(22)12-6-15/h1-12,20-21H Y Key: FYEHYMARPSSOBO-UHFFFAOYSA-N Y InChI=1/C19H14O3/c20-16-7-1-13(2-8-16)19(14-3-9-17(21)10-4-14)15-5-11-18(22)12-6-15/h1-12,20-21H Key: FYEHYMARPSSOBO-UHFFFAOYAG
SMILES C1=CC(=O)C=CC1=C(C2=CC=C(C=C2)O)C3=CC=C(C=C3)O
Properties
Chemical formula	C19H14O3
Molar mass	290.318 g·mol−1
Appearance	see text
Density	1.283 g/cm3
Melting point	308 °C (586 °F; 581 K) (decomposes)
Solubility in water	Insoluble
UV-vis (λmax)	482 nm[1]
Magnetic susceptibility (χ)	-161.4·10−6 cm3/mol
Hazards
GHS labelling:
Pictograms	[1]
Signal word	Danger
Hazard statements	H315, H319, H335[1]
Precautionary statements	P261, P305+P351+P338[1]
NFPA 704 (fire diamond)	1 1 0
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

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

Synthesis

Aurin was first prepared in 1834 by the German chemist Friedlieb Ferdinand Runge, who obtained it by distilling coal tar. He named it Rosölsäure or Rosaölsäure (red oil acid).^[2][3] In 1861, the German chemists Hermann Kolbe and Rudolf Schmitt presented the synthesis of aurin by heating oxalic acid and creosote (which contains phenol) in the presence of concentrated sulfuric acid.^[4] (Gradually, chemists realized that commercial aurin was not a pure compound, but was actually a mixture of similar compounds.^[5][6])

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

Safety

Aurin may cause eye, skin, and respiratory tract irritation. Ingestion and inhalation should be avoided.

Aurin was reported to have endocrine disruptor chemical (EDC) properties.^[7]: 149

References

1. Sigma-Aldrich Co., p-Rosolic acid. Retrieved on 2014-05-06.
2. Runge, F. F. (1834). "Ueber einige Produkte der Steinkohlendestillation" [On some products of coal tar distillation]. Annalen der Physik und Chemie (in German). 31 (5): 65–78. Bibcode:1834AnP...107...65R. doi:10.1002/andp.18341070502. ; see p. 70.
3. In 1859, the German-English chemist Hugo Müller (de) (1833–1915) found that rosolic acid could be produced simply by mixing phenol and calcium carbonate and then exposing the mixture to air for a prolonged time. Müller, Hugo (1859). "Note on rosolic acid". Quarterly Journal of the Chemical Society. 11 (1): 1–5. doi:10.1039/QJ8591100001.
4. Kolbe, H.; Schmitt, R. (1861). "Rother Farbstoff aus dem Kreosot" [Red dye from creosote]. Annalen der Chemie (in German). 119: 169–172.
5. See the papers of the English chemist Richard S. Dale and the German-English chemist Carl Schorlemmer and of the German chemist Heinrich Fresenius (de) (1847–1920).

   • Dale, R.S.; Schorlemmer, C. (1871). "On aurin". Journal of the Chemical Society. 24: 466–467. doi:10.1039/JS8712400466.
   • Dale, R.S.; Schorlemmer, C. (1872). "On aurin". Journal of the Chemical Society. 25: 74–75.
   • Dale, R.S.; Schorlemmer, C. (1873). "On aurin". Journal of the Chemical Society. 26: 434–444. doi:10.1039/JS8732600434.
   • Dale, R.S.; Schorlemmer, C. (1879). "On aurin, part II". Journal of the Chemical Society. 35: 148–159. doi:10.1039/CT8793500148.
   • Fresenius, H. (1871). "Ueber Rosolsäure" [On rosolic acid]. Journal für praktische Chemie. 2nd series (in German). 3: 477–480. doi:10.1002/prac.18710030149.
   • A review of findings about aurin up to 1872 appeared in: Fresenius, H. (1872). "Ueber das Corallin" [On corallin]. Journal für praktische Chemie. 2nd series (in German). 5 (4): 184–191. doi:10.1002/prac.18720050117.
   • Fresenius, H. (1872). "Corallin". Journal of the Chemical Society. 25: 705–706.
6. Thorpe, Thomas Edward, ed., A Dictionary of Applied Chemistry, 2nd ed. (London, England: Longmans, Green, and Co., 1913), vol. 5, "Triphenylmethane colouring matters," p. 551. From p. 551: "The researches of Dale and Schorlemmer, Zulkowski, and others have shown that common aurin consists of a mixture of a number of substances, which, in a pure state, are well crystallised."
7. Blair, R. M. (1 March 2000). "The Estrogen Receptor Relative Binding Affinities of 188 Natural and Xenochemicals: Structural Diversity of Ligands". Toxicological Sciences. 54 (1): 138–153. doi:10.1093/toxsci/54.1.138. ISSN 1096-0929. PMID 10746941.

External links

• MSDS at Oxford University
• History of aurin in Heinrich Caro and the creation of modern chemical industry
• "Aurin" . New International Encyclopedia. 1905.