Eosin Y

Eosin Y also called C.I. 45380[1][2] or C.I. Acid Red 87,[2][1] is the form of eosin most commonly used in histology, most notably in the H&E (Haematoxylin and Eosin) stain.[1] Eosin Y is also widely used in the Papanicolaou stain (or Pap stain used in the Pap test) and the Romanowsky type cytologic stains.[1][2] It is also used as a photosensitizer in organic synthesis.[3]

Eosin Y

Names
IUPAC name 2-(2,4,5,7-tetrabromo-6-oxido-3-oxo-3H-xanthen-9-yl)benzoate [in its deprotonated form]
Identifiers
CAS Number	17372-87-1
3D model (JSmol)	Interactive image
ChEBI	CHEBI:52053
ChEMBL	ChEMBL411675
ChemSpider	10580
ECHA InfoCard	100.037.629
MeSH	Eosine+Yellowish-(YS)
PubChem CID	11048
UNII	TDQ283MPCW
CompTox Dashboard (EPA)	DTXSID0025234
InChI InChI=1S/C20H8Br4O5.2Na/c21-11-5-9-13(7-3-1-2-4-8(7)20(27)28)10-6-12(22)17(26)15(24)19(10)29-18(9)14(23)16(11)25;;/h1-6,25H,(H,27,28);;/q;2*+1/p-2 Key: SEACYXSIPDVVMV-UHFFFAOYSA-L InChI=1/C20H8Br4O5.2Na/c21-11-5-9-13(7-3-1-2-4-8(7)20(27)28)10-6-12(22)17(26)15(24)19(10)29-18(9)14(23)16(11)25;;/h1-6,25H,(H,27,28);;/q;2*+1/p-2 Key: SEACYXSIPDVVMV-NUQVWONBAJ
SMILES c1ccc(c(c1)c2c3cc(c(c(c3oc-4c(c(=O)c(cc24)Br)Br)Br)[O-])Br)C(=O)[O-].[Na+].[Na+]
Properties
Chemical formula	C20H6Br4Na2O5
Molar mass	647.89052
Appearance	Red powder
Density	1.018 g·cm^−3
Melting point	295.5 °C (563.9 °F; 568.6 K)
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

References

1. Bancroft, John; Stevens, Alan, eds. (1982). The Theory and Practice of Histological Techniques (2nd ed.). Longman Group Limited.
2. Lillie, Ralph Dougall (1977). H. J. Conn's Biological stains (9th ed.). Baltimore: Williams & Wilkins. pp. 692p.
3. Diercxsens, Nicolas (2017-04-10), "Eosin Y", Encyclopedia of Reagents for Organic Synthesis, Chichester, UK: John Wiley & Sons, Ltd, pp. 1–3, doi:10.1002/047084289x.rn02033, ISBN 978-0-470-84289-8