Safranin

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Safranin

Systematic name	Safranin
Chemical formula	C_xH_xN_xO_x
Molecular mass	xx.xx g/mol
Density	x.xxx g/cm³
Melting point	xx.x °C
Boiling point	xx.x °C
CAS number	[xx-xx-xx]
SMILES	xxxx
Disclaimer and references

Safranin (also Safranin O or basic red 2) is a biological stain used in histology and cytology. Safranin is used as a counterstain in some staining protocols, colouring all cell nuclei red. This is the classic counterstain in a Gram stain. It can also be used for the detection of cartilage, mucin and mast cell granules.

Safranin typically has the chemical structure shown at right (sometimes described as dimethyl safranin). There is also trimethyl safranin, which has an added methyl group in the ortho- position of the lower ring. Both compounds behave essentially identically in biological staining applications, and most manufacturers of safranin don't distinguish between the two. Commercial safranin preparations often contain a blend of both types.

Sarfanin also used as redox indicator in analytical chemistry.

[edit] Safranines

Image:Safranine.gif

Molecular structure of the Safranine cation

Safranines are the azonium compounds of symmetrical 2,8-dimethyl-3,7-diamino-phenazine. They are obtained by the joint oxidation of one molecule of a para-diamine with two molecules of a primary amine; by the condensation of para-aminoazo compounds with primary amines, and by the action of para-nitrosodialkylanilines with secondary bases such as diphenylmetaphenylenediamine. They are crystalline solids showing a characteristic green metallic luster; they are readily soluble in water and dye red or violet. They are strong bases and form stable monacid salts. Their alcoholic solution shows a yellow-red fluorescence. Phenosafranine is not very stable in the free state; its chloride forms green plates. It can be readily diazotized, and the diazonium salt when boiled with alcohol yields aposafranine or benzene induline, C₁₈H₁₂N₃. F. Kehrmann showed that aposafranine could be diazotized in the presence of cold concentrated sulfuric acid, and the diazonium salt on boiling with alcohol yielded phenylphenazonium salts. Aposafranone, C₁₈H₁₂N₂O, is formed by heating aposafranine with concentrated hydrochloric acid. These three compounds are perhaps to be represented as ortho- or as para-quinones. The "safranine" of commerce is a ortho-tolusafranine. The first aniline dye-stuff to be prepared on a manufacturing scale was mauveine, which was obtained by Sir W.H. Perkin by heating crude aniline with potassium bichromate and sulfuric acid. Mauveine was converted to parasafranine (1,8-dimethyl Safranine) by Perkin in 1879 by oxidative/reductive loss of the 7-N-para-tolyl group.

[edit] External links

Safranin O Staining Protocol
Safranine has recently been employed as the cationic component of a tecton used to build a porous anionic Hydrogen Bonded Network. (10.1021/ja042233m)
The InChI identifier is 1/C20H18N4/c1-12-8-17-19(10-15(12)21)24(14-6-4-3-5-7-14)20-11-16(22)13(2)9-18(20)23-17/h3-11H,1-2H3,(H3,21,22)/p+1]]
Link page to external chemical sources.

This article incorporates text from the Encyclopædia Britannica Eleventh Edition, a publication now in the public domain.

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