Chemical Properties
orange-brown powder
Uses
Eosin Acid C.I. No. 45380 (CAS# 15086-94-9) is a photo-senseitive organic catalyst and has been used in the photocatalytic, diastereoselective additions of 1-sulfoximidoyl-1,2-benziodoxoles to styrenes, and in the stereoselective synthesis of 2-deoxyglycosides from glycals. Dyes and metabolites.
Preparation
Fluorescein (C.I. Acid Yellow 73, C.I. 45350) in water or ethanol solution bromide into four bromine derivatives, And made into a free acid form..
Definition
ChEBI: Bromoeosin is an organobromine compound. It is functionally related to a fluorescein (lactone form).
Biological Activity
Eosin Y is a xanthene dye and is used for the differential staining of connective tissue and cytoplasm. In histopathology, it is applied as a counterstain after hematoxylin and before methylene blue. It is also used as a background stain, thereby giving contrast to the nuclear stains.
Synthesis
The general procedure for the synthesis of 2',4',5',7'-tetrabromo-3',6'-dihydroxy-3H-spiro[isobenzofuran-1,9'-xanthene]-3-one from 3',6'-dihydroxy-3H-spiro[isobenzofuran-1,9'-xanthene] is as follows: fluorescein in the form of the lactone (1 eq.), NaBr (16 eq.), and Oxone? ( 6 equiv, 2KHSO5-KHSO4-K2SO4) were mixed and ground in an agate mortar until uniformly fine. The resulting solid mixture was reacted in an oven at 200 °C for 12 h. Upon completion of the reaction, the target product tetrabromofluorescein (4Br-F) was obtained in near 100% yield in the commercial disodium salt form known as eosin Y. The reaction mixture was diluted with water and the product was extracted with ethyl acetate. The product was characterized by mass spectrometry (ESI-MS) and spectroscopic techniques (1H-NMR and 13C-NMR). The specific data were as follows: ESI-MS (+) of 4Br-F: m/z 670.4 [M + H]+; 1H NMR (CH3OD): δ 7.04 ppm (s, 1H and 8H), 7.23 (d, J = 8.0 Hz, 3H), 7.72 (ddd, J = 8.0, 8.0, 1.2 Hz, 5H), 7.79 (ddd, J = 8.0, 8.0, 1.2 Hz, 4H), 8.09 ppm (d, J = 8.0 Hz, 6H).
Properties and Applications
brilliant yellow red. Soluble in water and ethanol for blue light red, with yellow green fluorescence. In concentrated sulfuric acid to yellow, dilution after yellow red precipitation.
References
[1] Patent: US2008/61289, 2008, A1. Location in patent: Page/Page column 6-7
[2] Fortschr. Teerfarbenfabr. Verw. Industriezweige, vol. 5, p. 216
[3] Journal of the American Chemical Society, 1927, vol. 49, p. 1278
[4] Justus Liebigs Annalen der Chemie, 1876, vol. 183, p. 31
[5] Justus Liebigs Annalen der Chemie, 1910, vol. 372, p. 109
