Scarlet Crocein

Mixtures of minium with other colours or with white substances, heightened in colour by artificial organic dyes (usually eosin, cochineal scarlet, crocein, ponceau and the like), or, in some cases, white substances (barium sulphate) coloured with lakes of artificial organic dyes, are often sold as imitations or substitutes of cinnabar and vermilion. 

Cristsll, c., = Kristall, fete. CzocflDS[Pg.94]

Both these sulphonic acids of amidoazobenzene, and especially the disulphonic acid, are valuable yellow dyestuffs, and the sodium salt of the latter comes into commerce as Acid Yellow or Fast Yellow. A further application of these acids is in the preparation of tetrazo-dyestuflFs, for example Biebrich- and Crocein-scarlets. 

The sulphonic acids of this compound come into commerce as Biebrich and Crocein scarlets, according to the position of the sulpho-group. 

This body [61] is known as CroceTn Scarlet 3B, and although not producing fast shades is used, in cotton-dyeing. Crocein Scarlet 7 B is a dyestuff of somewhat bluer shade, and is obtained from orthoamidoazotoluenesulphonic acid in the same manner. The tetrazo-dyes prepared from y3-naphthol- -sulphonic acid give soluble crystalline calcium salts, while those from the other acid give amorphous and insoluble calcium salts. 

Lissamine Flavine FF Lissamine Fast Yellow 20 Naphthalene Orange G Croceine Scarlet 3B Lissamine Fast Red BG Ultralan Yellow R Coomassie Yellow 7G Ultralan Red B Coomassie Milling Scarlet 5B... 

Biebrich scarlet was discovered in 1878/9, a very pure red disazo dye said originally to rival cochineal in brightness . It is described by Zerr and Riibencamp (1906). Synonyms include Ponceau Biebrich Scarlet, Cl 26905/Acid Red 66, Croceine Scarlet and Double Scarlet BSF. Now principally used as a histological stain. 

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