Bismarck brown Y

Bismarck brown Y also called C.I. 21000^[1] and C.I. Basic Brown 1,^[1] is a diazo dye with the idealized formula [(H₂N)₂C₆H₃N₂]₂C₆H₄. The dye is a mixture of closely related compounds. It was one of the earliest azo dyes, being described in 1863 by German chemist Carl Alexander von Martius. It is used in histology for staining tissues.^[2]

Bismarck brown Y

Names
Other names Bismarck brown Manchester brown Phenylene brown Basic Brown 1 C.I. 21000 Vesuvine BA
Identifiers
CAS Number	8005-77-4 N
3D model (JSmol)	Interactive image Interactive image
ChemSpider	13374 N
ECHA InfoCard	100.030.273
PubChem CID	13981
CompTox Dashboard (EPA)	DTXSID5024558
InChI InChI=1S/C18H18N8/c19-11-4-6-17(15(21)8-11)25-23-13-2-1-3-14(10-13)24-26-18-7-5-12(20)9-16(18)22/h1-10H,19-22H2/b25-23+,26-24+ N Key: BDFZFGDTHFGWRQ-OGGGYYITSA-N N InChI=1/C18H18N8/c19-11-4-6-17(15(21)8-11)25-23-13-2-1-3-14(10-13)24-26-18-7-5-12(20)9-16(18)22/h1-10H,19-22H2/b25-23+,26-24+ Key: BDFZFGDTHFGWRQ-OGGGYYITBR
SMILES CC1=C(C=C(C=C1)N=NC2=C(C=C(C(=C2)C)N)N)N=NC3=C(C=C(C(=C3)C)N)N N(=N/c1ccc(cc1N)N)\c3cccc(/N=N/c2ccc(N)cc2N)c3
Properties
Chemical formula	C18H18N8·2HCl
Molar mass	419.31 g/mol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Synthesis

The dye is simple to prepare because the diamine serves both as a source of the diazonium cation and as the coupling partner in the azo coupling reaction. The synthesis is thought to start with double diazotization of 1,3-phenylenediamine:

(H₂N)₂C₆H₄ + 2 H⁺ + 2 HNO₂ → [C₆H₄(N₂)₂]²⁺ + 2 H₂O

It is assumed that this bis(diazonium) ion subsequently attacks two equivalents of 1,3-phenylenediamine:

2 (H₂N)₂C₆H₄ + [C₆H₄(N₂)₂]²⁺ → 2 H⁺ + [(H₂N)₂C₆H₃N₂]₂C₆H₄

In some cases, toluenediamines are used in addition to the phenylenediamine. Furthermore, the resulting dye is thought to consist of oligomers with three or more diazo groups.^[2]

Uses

Bismarck brown Y stains acid mucins to yellow color. It also stains mast cell granules brown.^[3] It can be used with live cells. It is also used to stain cartilage in bone specimens, as one of Kasten's Schiff-type reagents in the periodic acid-Schiff stain to stain cellulose, and in Feulgen stain to stain DNA. It was more common in the past; today it is partially replaced by other stains. It has also been used to give soap an amber color in the past.^[4]

Bismarck brown Y is a constituent of Papanicolaou stain.^[1]

It can also be used as a counterstain for Victoria blue R for staining of acid-fast microorganisms.