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Merck

C6767

Congo Red

Dye content ≥35 %, Powder

Synonym(s):

Congo Red 4B, Cosmos Red, Cotton Red B, Cotton Red C, Direct Red 28, Direct Red R, Direct Red Y

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About This Item

Empirical Formula (Hill Notation):
C32H22N6Na2O6S2
CAS Number:
Molecular Weight:
696.66
UNSPSC Code:
12171500
NACRES:
NA.47
PubChem Substance ID:
EC Number:
209-358-4
MDL number:
Colour Index Number:
22120
Beilstein/REAXYS Number:
3894858
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Product Name

Congo Red, Dye content ≥35 %

form

powder

Quality Level

composition

Dye content, ≥35%

technique(s)

titration: suitable

color

red-brown

pH

6.7 (10 g/L)

mp

>360 °C (lit.)

solubility

H2O: 1 mg/mL

application(s)

diagnostic assay manufacturing
hematology
histology

storage temp.

room temp

SMILES string

[Na+].[Na+].Nc1c(cc(c2ccccc12)S([O-])(=O)=O)\N=N\c3ccc(cc3)-c4ccc(cc4)\N=N\c5cc(c6ccccc6c5N)S([O-])(=O)=O

InChI

1S/C32H24N6O6S2.2Na/c33-31-25-7-3-1-5-23(25)29(45(39,40)41)17-27(31)37-35-21-13-9-19(10-14-21)20-11-15-22(16-12-20)36-38-28-18-30(46(42,43)44)24-6-2-4-8-26(24)32(28)34;;/h1-18H,33-34H2,(H,39,40,41)(H,42,43,44);;/q;2*+1/p-2/b37-35+,38-36+;;

InChI key

IQFVPQOLBLOTPF-HKXUKFGYSA-L

Application

  • Congo red has been used as a histochemical stain for the quantification of amyloid deposits in brain tissues.
  • It has been used as a cell wall inhibiting agent in fungus Cryptococcus neoformans.
  • It has also been used to study microstructural details in the cell walls of raw potato and fried potato using confocal microscopy.

Biochem/physiol Actions

Congo red is a benzidine-based anionic diazo dye. It is a histological dye which binds to many amyloid proteins and is used for the quantification of amyloid β-peptide aggregation. Congo red also interacts with β-D-glucans, polysaccharides containing continuous β-(1→4)-linked D-glucopyranosyl units and some hemicellulosic galactoglucomannans.


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pictograms

Health hazard

signalword

Danger

Hazard Classifications

Carc. 1B - Repr. 2

Storage Class

6.1C - Combustible acute toxic Cat.3 / toxic compounds or compounds which causing chronic effects

wgk

WGK 3

ppe

Eyeshields, Gloves, type P3 (EN 143) respirator cartridges


Regulatory Listings

Regulatory Listings are mainly provided for chemical products. Only limited information can be provided here for non-chemical products. No entry means none of the components are listed. It is the user’s obligation to ensure the safe and legal use of the product.

573-58-0

CAS No.

573-58-0

CAS No.


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Kinetic study and equilibrium isotherm analysis of Congo Red adsorption by clay materials.
Chemical Engineering Journal, 148, 354-364 (2009)
Quantification of cerebral amyloid angiopathy and parenchymal amyloid plaques with Congo red histochemical stain.
Wilcock DM, et al.
Nature Protocols, 1, 1591-1591 (2006)
PKC1 is essential for protection against both oxidative and nitrosative stresses, cell integrity, and normal manifestation of virulence factors in the pathogenic fungus Cryptococcus neoformans.
Gerik KJ, et al.
Eukaryotic Cell, 7, 1685-1685 (2008)