Acid Red 66

Structural formula
	Structural formula CI Acid Red 66 as a free acid
General
Surname	Acid Red 66
other names	Disodium 2 - [(2-hydroxy-1-naphthyl) diazenyl] -5 - [(4-sulfonatophenyl) diazenyl] benzenesulfonate ( IUPAC ); CI 26905; Biebrich scarlet fever; Imperial Scarlet; Crocein scarlet; Real ponceau B, 3RB or RS; Neurot L;
Molecular formula	C 22 H 14 N 4 NA 2 O 7 S 2
Brief description	dark red solid
External identifiers / databases
EC number	224-084-5
ECHA InfoCard	100,021,895
PubChem	20170
ChemSpider	17967084
Wikidata	Q833649
properties
Molar mass	556.5 g · mol -1
Physical state	firmly
solubility	soluble in water and ethanol
safety instructions
GHS labeling of hazardous substances	no GHS pictograms
	no GHS pictograms
H and P phrases	H: no H-phrases
	P: no P-phrases
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

CI Acid Red 66 is the name for a bisazo dye from the group of acid dyes . The red-brown disodium salt dissolves well in water with a yellow-red color. It dyes wool and silk cochineal-like red. It was developed in 1878 by Rudolf Nietzki and manufactured from 1879 by Kalle in Wiesbaden-Biebrich under the name Biebricher Scharlach .

Acid Red 66 was the first industrially produced disazo dye.

Manufacturing

Acid Red 66 ( 5 ), by diazotization of sulfanilic acid ( 1 ) and subsequent coupling to orthanilic . In order to avoid the formation of triazenes , the amino group of the orthanilic acid can be protected by reacting it with the adduct of formaldehyde / bisulfite ( 2 ). The monoazo dye ( 3 ) obtained is diazotized again after the protective group has been split off and coupled to β-naphthol ( 4 ).

Synthesis of CI Acid Red 66 (Biebrich scarlet fever)

swell

Otto Lueger : Lexicon of the entire technology . 2nd edition, Deutsche Verlags-Anstalt, Stuttgart a. Leipzig, 1904–1920.
@1@ 2( Page no longer available , search in web archives: Wiesbadener Tagblatt from August 15, 2008 )

Individual evidence

↑ ^a ^b ^c ^d data sheet Acid Red 66 from Sigma-Aldrich , accessed on December 27, 2019 ( PDF ).

[sigma-1] ta sheet Acid Red 66 from Sigma-Aldrich , accessed on December 27, 2019 ( PDF ).