Name = Safranin
ImageFile = Safranin Cl.svg
ImageName = Safranin
ImageFile1 = Safranin-3D-balls.png
ImageSize1 = 200px
ImageName1 = Safranin
IUPACName = Safranin
Section1 = Chembox Identifiers
Section2 = Chembox Properties
Safranin (also Safranin O or basic red 2) is a biological stain used in
histologyand 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[cite journal | author = Rosenberg L | title = Chemical Basis for the Histological Use of Safranin O in the Study of Articular Cartilage | journal = J Bone Joint Surg Am. | volume = 53 | issue = 1 | pages = 69–82 | year = 1971 | pmid = 4250366 | doi = | url = http://www.ejbjs.org/cgi/content/abstract/53/1/69 | issn = | format = abstract ] , mucinand mast cellgranules.
Safranin typically has the chemical structure shown at right (sometimes described as dimethyl safranin). There is also trimethyl safranin, which has an added
methyl groupin 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.
Safranin also used as
redox indicatorin analytical chemistry.
Safranines are the azonium compounds of
symmetrical2,8-dimethyl-3,7-diamino-phenazine. They are obtained by the joint oxidationof one moleculeof 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 crystallinesolids showing a characteristic green metallic luster; they are readily soluble in water and dyeblue 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 chlorideforms 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 anilinedye-stuff to be prepared on a manufacturing scale was mauveine, which was obtained by Sir William Henry Perkinby heating crude aniline with potassiumbichromate and sulfuric acid. Mauveine was converted to "parasafranine" (1,8-dimethyl Safranine) by Perkin in 1878 by oxidative/reductive loss of the 7-N-"para"-tolyl group. [cite journal | journal = J. Chem. Soc., Trans.| year = 1879 | volume = 35 | pages = 717–732 | doi = 10.1039/CT8793500717 | title = LXXIV.—On mauveine and allied colouring matters | author = W. H. Perkin F.R.S.]
* [http://www.ihcworld.com/_protocols/special_stains/safranin_o.htm Safranin O Staining Protocol]
*Safranine has recently been employed as the cationic component of a tecton used to build a porous
Wikimedia Foundation. 2010.