Eosin Y

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Structural formula
Eosin Y
General
Surname Eosin Y
other names
  • Eosin G.
  • Tetrabromofluorescein
  • 2 ', 4', 5 ', 7'-tetrabromo-3', 6'-dihydroxyspiro [2-benzofuran-3,9'-xanthene] -1-one disodium salt
  • CI 45380
Molecular formula C 20 H 6 Br 4 Na 2 O 5
Brief description

red solid

External identifiers / databases
CAS number 17372-87-1
EC number 241-409-6
ECHA InfoCard 100.037.629
PubChem 11048
Wikidata Q1089206
properties
Molar mass 691.86 g mol −1
Physical state

firmly

density

1.02 g cm −3

Melting point

295-296 ° C

solubility

good in water (300 g l −1 at 20 ° C)

safety instructions
GHS labeling of hazardous substances
07 - Warning

Caution

H and P phrases H: 319
P: 260-305 + 351 + 338
Toxicological data

2344 mg kg −1 ( LD 50 ,  mouse ,  oral )

As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Eosin Y (from Greek ἠώς EOS , German , Dawn ' ) is a red, acid dye from the group of xanthene dyes, as well as triphenylmethane , and can be used for dyeing textiles and paper.

In addition to the commonly employed Eosin Y (for English yellowish , yellowish ' ), which is also Eosin B (for engl. Bluish , bluish' ) is used, which in contrast to the yellow tinge of Eosin Y shows a blue cast. In eosin B , two of the bromine atoms have been replaced by nitro groups . The eosins are derived from fluorescein .

use

Eosin Y
Fluorescein and Eosin ( historical dye collection of the TU Dresden )

medicine

The main areas of application are medicine and biology, where eosin Y is used to stain cells , etc. a. in the blood (see also eosinophils and hematoxylin-eosin staining ). Cell components such as B. stained the cytoplasm reddish. In addition to eosin Y, eosin B can also be used for some applications.

Eosin Y and similar dyes were - before cortisone became established - e.g. B. used to treat open neurodermatitis : fungi and bacteria are killed and the skin is supported in healing.

Since eosin Y also contains bromine atoms and bromine is one of the halogens , it also has a disinfectant meaning (similar to the other halogens chlorine and iodine ) and is used by dermatologists - as a replacement for mercurochrome - in the form of a z. B. two percent aqueous solution used for wound disinfection or healing. However, it has only a weak antibacterial effect.

pH indicator

Eosin is also used as a pH indicator . Eosin Y changes from yellow (<2) to green-fluorescent (> 2) at approx. PH 2. Eosin B changes from colorless (<≈ 1.7) to pink-fluorescent (> ≈ 1.7) at approx. PH 1.7–1.8, but is not very widespread for this purpose.

Quantitative halide determination according to Fajans

Eosin Y is also suitable as a simple, very precise indicator for precipitation titrations. An analyte which contains an unknown concentration of iodide ions is determined with a standard AgNO 3 solution until flake formation (due to poorly soluble AgI). After the equivalent point is exceeded, the AgI colloids are positively charged by excess Ag + ions on the surface and are able to adsorb eosin anions, which leads to a color change through interaction with the delocalized π-electron system of the dye. You can see a sharp color change from yellow to pink.

dye

Eosin Y was used as a coloring agent in lipsticks until the 1980s . Because of its toxic effect, it has since been replaced by pigments .

Hydrology

In hydrology , Eosin Y is used for color experiments . Because it is very sensitive to light, it is mainly used for groundwater issues.

See also

Individual evidence

  1. ↑ Entry on Eosin Y in the ChemIDplus database of the United States National Library of Medicine (NLM), accessed on November 7, 2016.
  2. ↑ Eosin Y data sheet (PDF) from Carl Roth , accessed on February 26, 2010.
  3. ↑ Data sheet Eosin Y disodium salt from Sigma-Aldrich , accessed on May 12, 2017 ( PDF ).
  4. ↑ a b Eosin Y data sheet (PDF) from Merck , accessed on February 26, 2010.
  5. ↑ a b Entry on disodium 2- (2,4,5,7-tetrabromo-6-oxido-3-oxoxanthen-9-yl) benzoate in the GESTIS substance database of the IFA , accessed on January 10, 2017(JavaScript required) .
  6. ↑ Eosin Y data sheet from Acros, accessed on February 26, 2010.
  7. ^ Henry George Liddell, Robert Scott: A Greek-English Lexicon, ἠώς. Retrieved March 20, 2018 .
  8. ↑ PSCHYREMBEL, p. 355, sv "Disinfectants".
  9. ↑ Heike Fischer, Holger Reimann: Eosin perhaps superfluous, but not questionable. In: Pharmaceutical newspaper. Edition 7/2000.

Web links

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