Congo red
Basic information
- CAS
573-58-0- Standard SMILES
Nc1c(N=Nc2ccc(-c3ccc(N=Nc4cc(S(=O)(=O)[O-])c5ccccc5c4N)cc3)cc2)cc(S(=O)(=O)[O-])c2ccccc12.[Na+].[Na+]- InChIKey
IQFVPQOLBLOTPF-UHFFFAOYSA-L- Molecular formula
- C32H22N6Na2O6S2
- Average molar mass
- 696.7 g/mol
- Monoisotopic mass
- 696.08376298
Overview
Congo Red is an indicator dye that is blue-violet at pH 3.0 and red at pH 5.0. It contains a 3,3'-(biphenyl-4,4'-diyldidiazene-2,1-diyl)bis(4-aminonaphthalene-1-sulfonate). It is functionally related to a 3,3'-(biphenyl-4,4'-diyldidiazene-2,1-diyl)bis(4-aminonaphthalene-1-sulfonic acid).
Names & identifiers
- Preferred name
- Congo red
- IUPAC
- disodium;4-amino-3-[[4-[4-[(1-amino-4-sulfonatonaphthalen-2-yl)diazenyl]phenyl]phenyl]diazenyl]naphthalene-1-sulfonate
- English name
- Congo Red
- Molecular formula
- C32H22N6Na2O6S2
- Molecular weight
- 696.66
Names & synonyms
Congo red573-58-0DIRECT RED 28C.I. Direct Red 28Congazone sodiumMitsui Congo RedBenzo Congo RedCotton Red LHaemomedicalHaemonormHemorrhagylHispamin Congo 4B
Show more names
DIRECT REDCONGOkongorotLITHIUM HYDROXIDE 1H2OredkCongoReS NO 360CongorotCI 22120
SolucongoBrasilamina congo 4BSugai Congo RedAtul Congo RedVondacel Red CLKayaku Congo RedDirect Red KAzocard Red Congo
Database identifiers
- CAS
573-58-0- PubChem CID
- 11313
- DTXSID
DTXSID4022816- ChEBI
CHEBI:34653- UNII
- 3U05FHG59S
- Nikkaji
- J6.549H
Properties
Computed structural properties
- Topological polar surface area
- 233 Ų
- Hydrogen bond donors
- 2
- Hydrogen bond acceptors
- 12
- Rotatable bonds
- 5
- Heavy atoms
- 48
- Formal charge
- 0
- Complexity
- 1,180
Experimental & physicochemical properties
Endocrine DisruptorsPotential endocrine disrupting compound
Physicochemical properties
- Melting point
- 360 °C · >360 °C (lit.)
- Density
- 0.995 g/mL · 0.995 g/mL at 25 °C
- bulk density
- 600 · 600-700kg/m3
- vapor pressure
- 1 Pa · <1 Pa
- storage temp.
- 5 °C · Store at +5°C to +30°C.
- solubility
- 2 O: · H2O: soluble10mg/mL
- form
- Powder/Solid
- pka
- 4.1 · 4.1(at 25℃)
- Colour Index
- 22120 · 22120
- color
- Red Brown
- PH Range
- 3 · 3(blue)-5.2(red)
- Odor
- Odorless
- PH
- 6.7 · 6.7 (10g/l, H2O, 20℃)
- Water Solubility
- soluble
Safety & regulation
Safety information is for reference only and does not replace the supplier’s Safety Data Sheet (SDS), applicable regulations, or professional assessment.
Safety data
- PPE
- Eyeshields, Gloves, type P3 (EN 143) respirator cartridges
- wgk
- 3
- tsca
- TSCA listed
- rtecs
- QK1400000
- hs_code
- 29215900
- Toxicity
- LD50 i.v. in rats: 190 mg/kg (Richardson, Dillon)
- risk_code
- 45-63-36
- Signal word
- Danger
- Symbol(GHS)
- GHS08
- hazard_code
- T,Xi
- safety_code
- 53-45-37/39-26
- Storage Class
- 6.1C - Combustible acute toxic Cat.3toxic compounds or compounds which causing chronic effects
- Hazard statements
- H350-H361d
- Hazard Classifications
- Carc. 1BRepr. 2
- Precautionary statements
- P201-P202-P280-P308+P313-P405-P501
- Hazardous Substances Data
- 573-58-0(Hazardous Substances Data)
Chemistry & industry
Applications
Uses1. It has been widely used in cotton, viscose dyeing. Because it can easily be transformed into blue when in acid, while there is no appropriate treatment to improve, the usage amount is gradually decreased since the advent of insoluble azo dyes and acid-resistant red 4BS, however, the amount used in the paper industry is quite large. It can also be used as indicators of acid-base, namely Congo red test paper. The measurable range pH is 3.0 (blue)-5.0 (red). It is also used for biological staining, analysis reagents. 2. An indicator frequently used in lab as well as a carcinogenic disperse dyes; used to standard test. 3. Used as an acid-base indicator, adsorption indicator and biological stain, etc. 4. Acid-base indicator, pH 3.0 (blue violet)~5.0 (red); detect the acidity of paper and hydrochloric acid in the gastric juice; test boric acid, cyanide; biological media additives; biological staining, such as embryo slices, plant mucin, cellulose, elastic tissue dyeing. 5. Mainly used for dyeing cotton, hemp, silk and other textile and paper products; it can also be used as an indicator.
DescriptionC.I. Direct red 28(Congo Red) is an odorless,brownish-red powder. Molecular weight =698.72. Meltingpoint =359℃. Soluble in water; solubility =25 g/L at25℃.
UsesDye, medicine (diagnostic aid), indicator, biological stain.
UsesCongo red is useful for staining and visual detection of amyloid deposits. It inhibits the accumulation of the scrapie-associated, protease-resistant isoform of protein PrP without affecting the metabolism of the normal isoform.
UsesCongo 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.
Upstream & downstream products
Upstream raw materials
Related reactions
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Compound notes
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