Eosin Y

• Eosin Y
• Tetrabromfluorescein
• 2 ', 4 ', 5 ', 7' -tetrabromo -3 ', 6'- dihydroxyspiro [2 -benzofuran- 3, 9' -xanthene ] -1-one disodium salt
• C. I. 45380

Red solid

Fixed

1.02 g · cm -3

295-296 ° C

Good in water ( 300 g · l-1 at 20 ° C)

Attention

2344 mg · kg -1 ( LD50, mouse, oral)

Template: Infobox chemical / molecular formula search available

Eosin Y (from the Greek εως " Dawn " ) is a red, acid dye from the group of xanthene dyes and can be used for dyeing textiles and paper.

In addition to the commonly used eosin Y ( for eng. Yellowish, yellowish '), is also the eosin B ( for eng. Bluish, bluish ' ) is used, in contrast to the yellow tinge of eosin Y shows a blue cast. When eosin B are two of the bromine atoms are replaced by nitro groups. The Eosine derived from fluorescein.

Use

Medicine

Main applications are in medicine and biology, where (see also eosinophilic granulocytes and hematoxylin -eosin stain ) serves eosin Y for staining cells, including the blood. This cell components such as the cytoplasm stained reddish eg. Eosin Y in addition can be used for some applications, Eosin B.

Eosin Y and similar dyes were - before cortisone prevailed - for example for the treatment of atopic dermatitis open used: Fungi and bacteria are killed and supports the skin in the healing process.

As eosin Y contains bromine and bromine atoms among the halogens, it is also a meaning disinfecting occurs ( similar to the other halogens, chlorine and iodine), and is used by dermatologists - as a replacement for mercurochrome - in the form of, for example two percent aqueous solution for disinfecting wounds and healing used. However, there is only weak antibacterial.

Eosin is also used as a pH indicator. Eosin Y beats at about pH 2 of yellow ( to <2) to green - fluorescent ( > 2). Eosin B lashes out at about pH 1.7-1.8 from colorless (< ≈ 1.7 ) to pink - fluorescent ( > ≈ 1.7 ), but is not widely used for this purpose.

Quantitative Halogenidbestimmung by Fajans

Eosin Y is also suitable as a simple very precise indicator for precipitation titrations. An analyte containing an unknown concentration of iodide ions is determined with a AgNO3 solution until the floc formation ( by sparingly soluble AgI ). According to the equivalent point is reached the AgI colloids are positively charged by excess Ag ions at the surface and assets Eosinanionen under deformation of their electron shell ( color change ) to adsorb. One can see a sharp color change from yellow to pink.

Dye

Until the 1980s, it used eosin Y as a dye in lipsticks. Because of the toxic effect it has since been replaced by pigments.

Hydrology

In hydrology Eosin Y is used for dyeing tests. Since it is very sensitive to light, it is mainly used for groundwater issues.