Artificial dyes Chemical properties Uses Production methods
ChemicalBook > CAS DataBase List > Congo Red

Congo Red

Artificial dyes Chemical properties Uses Production methods
Product Name
Congo Red
CAS No.
573-58-0
Chemical Name
Congo Red
Synonyms
DIRECT RED;DIRECT RED 28;kongorot;LITHIUM HYDROXIDE 1H2O;redk;CONGO;CongoRe;S NO 360;Congorot;CI 22120
CBNumber
CB1261000
Molecular Formula
C32H22N6Na2O6S2
Formula Weight
696.66
MOL File
573-58-0.mol
More
Less

Congo Red Property

Melting point:
>360 °C (lit.)
Density 
0.995 g/mL at 25 °C
vapor pressure 
<1 Pa
storage temp. 
Store at +5°C to +30°C.
solubility 
H2O: soluble10mg/mL
pka
4.1(at 25℃)
Colour Index 
22120
form 
Powder/Solid
color 
Red Brown
PH
6.7 (10g/l, H2O, 20℃)
PH Range
3(blue)-5.2(red)
Odor
Odorless
Water Solubility 
soluble
λmax
497nm, 488nm, 595nm
Merck 
14,2498
BRN 
3894858
Stability:
Stable. Incompatible with strong oxidizing agents.
Biological Applications
Detecting bacteria,protein folding disorders; treating dermatological disorders,neurodegenerative diseases,Alzheimer’s disease
Major Application
Waveguides, optical sensors, display devices, inks, fertilizer, pesticides, carbohydrates, treatment of pathogen infections, age-related macular degeneration
CAS DataBase Reference
573-58-0(CAS DataBase Reference)
EPA Substance Registry System
Congo Red (573-58-0)
More
Less

Safety

Hazard Codes 
T,Xi
Risk Statements 
45-63-36
Safety Statements 
53-45-37/39-26
WGK Germany 
3
RTECS 
QK1400000
TSCA 
Yes
HS Code 
29215900
Hazardous Substances Data
573-58-0(Hazardous Substances Data)
Toxicity
LD50 i.v. in rats: 190 mg/kg (Richardson, Dillon)
More
Less

Hazard and Precautionary Statements (GHS)

Symbol(GHS)
Signal word
Danger
Hazard statements

H350May cause cancer

Precautionary statements

P201Obtain special instructions before use.

P202Do not handle until all safety precautions have been read and understood.

P280Wear protective gloves/protective clothing/eye protection/face protection.

P308+P313IF exposed or concerned: Get medical advice/attention.

P405Store locked up.

P501Dispose of contents/container to..…

More
Less

N-Bromosuccinimide Price

Sigma-Aldrich
Product number
234610
Product name
Congo Red, High Purity
Packaging
500mg
Price
$105
Updated
2024/03/01
TCI Chemical
Product number
C0550
Product name
Congo Red
Purity
>98.0%(HPLC)
Packaging
25g
Price
$104
Updated
2024/03/01
Alfa Aesar
Product number
B24310
Product name
Congo Red, indicator grade
Packaging
25g
Price
$55.3
Updated
2023/06/20
Alfa Aesar
Product number
B24310
Product name
Congo Red, indicator grade
Packaging
100g
Price
$151
Updated
2023/06/20
Sigma-Aldrich
Product number
C6767
Product name
Congo Red
Purity
Dye content ≥35%
Packaging
25g
Price
$26.3
Updated
2024/03/01
More
Less

Congo Red Chemical Properties,Usage,Production

Artificial dyes

Congo red is aniline dye or coal tar dyes, and it has many types with very wide application. Its drawback is easy to fade by sunlight; aniline blue, bright green, methyl green are more easily fade. Be careful to handle the pH, and avoid direct sunlight when flaking, thus it will keep a few years without fading.
Congo red is an acid dye, a purplish red powder. It is soluble in water and alcohol, turning blue when in acid. It can be used as a dye as well as an indicator. In the production of plant slide, it is often used as a liner agent for hematoxylin or other cell dyes. When used in cytoplasm dyes, it can dye the cytosol or fibrin red. In the process of tissue slicing, it is used to dye nerve axis, elastic fibers, embryonic materials, etc. In addition, Congo red can be used for double staining with hematoxylin; it can also be used for amyloid staining. For it is soluble in water and alcohol, so washing and dehydration treatment should be quick.

Chemical properties

Congo red is red-brown powder, soluble in hot water and the cold water 10 times of its weight; the color of the solution is yellow-red; soluble in ethanol and the solution is orange; slightly soluble in acetone, while almost insoluble in ether. The solution is dark blue when in sulfuric acid, turning to light blue accompanied with the appearance of blue precipitate when diluted.
Its aqueous solution will form a blue floc when in concentrated hydrochloric acid. When added with acetic acid, the precipitate turned blue with a little purple to a precipitate with some red color.  It is insoluble in the concentration of caustic soda solution; susceptible to acid and salt which means even if its absorption of carbon dioxide from the air will make the color blue and dark, while dilute soda solution can restore the original color.
Information on the chemical properties, uses and production methods of artificial dyes Congo Red is compiled and edited by Chemcialbook.

Uses

1. 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.

Production methods

It is obtained by the coupling with  sodium naphthionate after the diazotization with benzidine, and then by salting out, filtration and drying in the system. The details are as follows: add 48.4 benzidine into 300ml of hydrochloric acid take 48.4g benzidine dissolved in 300ml hydrochloric acid (including 20ml of concentrated hydrochloric acid 20ml), add ice into the solution until the temperature is below 5 ℃; add 10% aqueous solutions prepared by 14.4g sodium nitrite after adding 30ml of concentrated hydrochloric acid.Add the diazonium salt solution slowly into the solution prepared by 150g sodium naphthionate and a little water after diazotization. Add 35g sodium carbonate slowly under the sufficient mixing after 30 minutes' standing, thus appearing an alkaline solution. Heating to 80℃, cooling, filtering, washing with saturated brine and drying can obtain the product. The materials consumption (kg/t) in industrial production are as follows: benzidine (100%) 200, sodium naphthionate (100%) 520, sodium nitrite (industry) 160, hydrochloric acid (31%) 330, soda ash (industrial) 340, fine salt 2500, turkey red oil 9, ethanol 60, sodium acetate 35, sodium sulfate 50.

Description

C.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℃.

Chemical Properties

brown-red powder

Chemical Properties

C.I. Direct red 28(Congo Red) is an odorless, brownish-red powder.

Uses

Dye, medicine (diagnostic aid), indicator, biological stain.

Uses

Congo 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.

Uses

  • 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.

Definition

ChEBI: An indicator dye that is blue-violet at pH 3.0 and red at pH 5.0.

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.

Safety Profile

Human poison by ingestion with cardovascular effects. Experimental poison by intravenous route. An experimental teratogen. Experimental reproductive effects. An eye irritant. Mutation data reported. When heated to decomposition it emits very toxic fumes of NOx, SOx, and Na2O

Potential Exposure

It is used as an indicator dye, a biological stain; a diagnostic aid in medicine; and a dye for fabric and paper.

First aid

If this chemical gets into the eyes, remove anycontact lenses at once and irrigate immediately for at least15 min, occasionally lifting upper and lower lids. Seek medical attention immediately. If this chemical contacts theskin, remove contaminated clothing and wash immediatelywith soap and water. Seek medical attention immediately. Ifthis chemical has been inhaled, remove from exposure,begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR ifheart action has stopped. Transfer promptly to a medicalfacility. When this chemical has been swallowed, get medical attention. If victim is conscious, administer water ormilk. Do not induce vomiting.

storage

Room temperature

Shipping

UN3143 Dyes, solid, toxic, n.o.s. or Dye intermediates, solid, toxic, n.o.s., Hazard Class: 6.1; Labels: 6.1-Poisonous materials, Technical Name Required

Properties and Applications

Standard

Acid Resistance

Alkali Resistance

Light Fastness

Soaping

Water

Fading

Stain

Fading

Stain

ISO

1

3

1

2

2

AATCC

1

3

2

1

3

Purification Methods

Crystallise the dye from aqueous EtOH (1:3). Dry it in air. [Beilstein 6 I 342.]

Incompatibilities

Contact with oxidizers may cause fire and explosion hazard. Incompatible with strong acids; reducing agents.

Congo Red Preparation Products And Raw materials

Raw materials

Sulfonated castor oil Sodium sulfate Benzidine Naphthionic acid

Preparation Products

TRIS(2-AMINOETHYL)AMINE Ammonium hydrogen difluoride 2-Aminoisobutyric Acid N-Carbobenzyloxyglycine Hyodeoxycholic acid 8-AZAGUANINE ETHYL LINOLEATE 2-Picolinic acid Diethyl nitromalonate
More
Less

Congo Red Suppliers

Americas 1 Austria 1 Belgium 1 Canada 1 China 286 Czech Republic 3 Europe 3 France 4 Germany 7 Hungary 1 India 55 Japan 8 Mexico 2 Poland 2 Switzerland 2 Turkey 1 United Kingdom 12 United States 58 USA 1 Global 449
MedChemexpress LLC
Tel
021-58955995
Fax
609-228-5909
Email
sales@medchemexpress.cn
Country
United States
ProdList
4861
Advantage
58
TargetMol Chemicals Inc.
Tel
+1-781-999-5354 +1-00000000000
Email
marketing@targetmol.com
Country
United States
ProdList
32165
Advantage
58
Aladdin Scientific
Tel
+1-+1(833)-552-7181
Email
sales@aladdinsci.com
Country
United States
ProdList
57505
Advantage
58
ApexBio Technology
Tel
--
Fax
--
Email
sales@apexbt.com
Country
United States
ProdList
6251
Advantage
58
Alfa Chemistry
Tel
--
Fax
--
Email
info@Alfa-Chemistry.com
Country
United States
ProdList
6814
Advantage
0
AccuStandard Inc
Tel
--
Fax
--
Email
info@bester.nl
Country
United States
ProdList
5300
Advantage
76
Redox Scientific
Tel
--
Fax
--
Email
info@redoxsci.com
Country
United States
ProdList
2380
Advantage
58
Abbey Color
Tel
--
Fax
--
Email
sales@abbeycolor.com
Country
United States
ProdList
28
Advantage
58
Organic Dyes & Pigments, LLC (ORCO)
Tel
--
Fax
--
Email
mdoyle@organicdye.com
Country
United States
ProdList
66
Advantage
58
Dudley Chemical Corp
Tel
--
Fax
--
Country
United States
ProdList
174
Advantage
58
MilliporeSigma (Sigma-Aldrich Corp.)
Tel
--
Fax
--
Email
@sial.com
Country
United States
ProdList
5414
Advantage
58
Alichem Inc.
Tel
--
Fax
--
Email
sales@alichem.com
Country
United States
ProdList
6167
Advantage
58
ACS Chemical
Tel
--
Fax
--
Country
United States
ProdList
36
Advantage
58
Selleck Chemicals LLC
Tel
--
Fax
--
Email
sales@selleckchem.com
Country
United States
ProdList
1848
Advantage
58
Hestia Laboratories, Inc.
Tel
--
Fax
--
Email
info@hestialabs.com
Country
United States
ProdList
167
Advantage
58
MedChemExpress
Tel
--
Fax
--
Email
sales@medchemexpress.com
Country
United States
ProdList
6398
Advantage
58
Riedel-de Haen AG
Tel
--
Fax
--
Country
United States
ProdList
6773
Advantage
87
TCI America
Tel
--
Fax
--
Email
sales@tciamerica.com
Country
United States
ProdList
6909
Advantage
75
Frontier Scientific, Inc.
Tel
--
Fax
--
Email
sales@frontiersci.com
Country
United States
ProdList
6222
Advantage
86
Matrix Scientific
Tel
--
Fax
--
Email
sales@matrixscientific.com
Country
United States
ProdList
6632
Advantage
80
AAT Bioquest, Inc.
Tel
--
Fax
--
Email
jack@aatbio.com
Country
United States
ProdList
169
Advantage
50
ChemService Inc.
Tel
--
Fax
--
Country
United States
ProdList
6379
Advantage
68
ProChem, Inc.
Tel
--
Fax
--
Email
prochem1@aol.com
Country
United States
ProdList
1691
Advantage
66
Lab Express
Tel
--
Fax
--
Email
sales@labexpress.com
Country
United States
ProdList
1577
Advantage
67
Dudley Chemical Corp.
Tel
--
Fax
--
Email
dudley@dudley-chem.com
Country
United States
ProdList
687
Advantage
64
Leonid Chemicals Private Limited
Tel
--
Fax
--
Email
careers@leonidchemicals.com
Country
United States
ProdList
1700
Advantage
43
Alfa Aesar
Tel
--
Fax
--
Email
tech@alfa.com
Country
United States
ProdList
6814
Advantage
81
Naugra Export
Tel
--
Fax
--
Country
United States
ProdList
1332
Advantage
47
HONEST JOY HOLDINGS LIMITED
Tel
--
Fax
--
Email
sales@honestjoy.cn
Country
United States
ProdList
6675
Advantage
54
Advance Scientific & Chemical
Tel
--
Fax
--
Email
sales@advance-scientific.com
Country
United States
ProdList
6419
Advantage
71
City Chemical LLC
Tel
--
Fax
--
Email
sales@citychemical.com
Country
United States
ProdList
6708
Advantage
72
TimTec Corporation
Tel
--
Fax
--
Country
United States
ProdList
1945
Advantage
58
SKC Inc.
Tel
--
Fax
--
Email
skcorder@skcinc.com
Country
United States
ProdList
1378
Advantage
76
Sciencelab.com, Inc.
Tel
--
Fax
--
Email
accounting@sciencelab.com
Country
United States
ProdList
4159
Advantage
82
Loba Chemie Pvt. Ltd.
Tel
--
Fax
--
Country
United States
ProdList
1945
Advantage
71
GFS Chemicals
Tel
--
Fax
--
Email
gfschem@gfschemicals.com
Country
United States
ProdList
3403
Advantage
75
AnaSpec, Inc.
Tel
--
Fax
--
Email
service@anaspec.com
Country
United States
ProdList
4871
Advantage
77
Electron Microscopy Sciences
Tel
--
Fax
--
Email
sgkcck@aol.com
Country
United States
ProdList
672
Advantage
81
AMRESCO Inc.
Tel
--
Fax
--
Email
info@amresco-inc.com
Country
United States
ProdList
760
Advantage
73
Polysciences, Inc.
Tel
--
Fax
--
Email
info@polysciences.com
Country
United States
ProdList
1118
Advantage
81
City Chemicals Corporation
Tel
--
Fax
--
Country
United States
ProdList
6460
Advantage
72
Eastern Chemical Corp.
Tel
--
Fax
--
Email
eastern@u-g.com
Country
United States
ProdList
2786
Advantage
34
Ricca Chemical Company
Tel
--
Fax
--
Country
United States
ProdList
363
Advantage
68
Pylam Products Company, Inc.
Tel
--
Fax
--
Email
sales@pylamdyes.com
Country
United States
ProdList
3257
Advantage
30
J.T. Baker-A Division of Mallinckrodt Baker, Inc.
Tel
--
Fax
--
Country
United States
ProdList
1066
Advantage
82
Anilax Enterprises Incorporated
Tel
--
Fax
--
Country
United States
ProdList
712
Advantage
68
Integra Chemical Company
Tel
--
Fax
--
Email
chemicals@integrachem.com
Country
United States
ProdList
716
Advantage
51
RAL Diagnostic Stains and Reagents Corporation
Tel
--
Fax
--
Email
biostains@yahoo.com
Country
United States
ProdList
79
Advantage
30
EMD Chemicals Inc.
Tel
--
Fax
--
Email
emdinfo@emdchemicals.com
Country
United States
ProdList
1525
Advantage
77
EMD Biosciences, Inc.
Tel
--
Fax
--
Email
technical@calbiochem.com
Country
United States
ProdList
6529
Advantage
66
More
Less

View Lastest Price from Congo Red manufacturers

TIANJIN XIANGRUI DYESTUFF CO.,LTD
Product
DIrect Congo Red, DIrect Red 28 573-58-0
Price
US $3.50/kg
Min. Order
25kg
Purity
99%
Supply Ability
20 tons
Release date
2022-10-25
Zhuozhou Wenxi import and Export Co., Ltd
Product
Direct Red 28 573-58-0
Price
US $15.00-10.00/KG
Min. Order
1KG
Purity
99%+ HPLC
Supply Ability
Monthly supply of 1 ton
Release date
2021-08-11
Career Henan Chemical Co
Product
Congo Red 573-58-0
Price
US $2.00/KG
Min. Order
1KG
Purity
Dye content 70%
Supply Ability
customise
Release date
2018-08-08

573-58-0, Congo RedRelated Search:

Molasses DIRECT FAST RED 3B Ammonium sulfamate Sulfamic acid monosodium salt Ethylenediaminetetraacetic acid disodium salt Nickel bis(sulphamidate) Sulfanilic acid Sulfamic acid Biphenyl Sodium N-cyclohexylsulfamate Sodium Monofluorophosphate Direct Black 38 Direct Orange 46 Direct Yellow 12 DIRECT BLUE 15 BRILLIANT YELLOW Congo red paper Benzidine

  • 3,3'-[(1,1'-BIPHENYL)-4,4'-DIYLBIS(AZO)]BIS(4-AMINO-1-NAPHTHALENESULFONIC ACID) 2NA
  • S NO 360
  • CONGO RED (CERT)
  • Congo Red (0.1% in Water) [for pH Determination]
  • 3,3'-[(Biphenyl-4,4'-diyl)bisazo]bis(4-amino-1-naphthalenesulfonic acid sodium) salt
  • 3,3'-[[1,1'-Biphenyl]-4,4'-diylbis(azo)]bis[4-amino-1-naphthalenesulfonic acid sodium] salt
  • Congo Ared 4b
  • Congo Red K
  • Congo Redsodium Salt
  • Bdirect Congo Red
  • 3,30-[[1,10-biphenyl]-4,40-diylbis-(azo)] Bis[4-amino-1-naphthalenesulfonic Acid] Disodium Salt
  • 1-naphthalenesulfonic Acid, 3,30-[[1,10-biphenyl]-4,40diylbis(azo)]bis[4-amino-, Disodium Salt
  • Congorot
  • Direct Congo Red
  • Sodium Diphenyldiazo-bis-a-naphthylaminesulfonate
  • Congo Red *UltraPure grade* *CAS 573-58-0*
  • CONGO RED FIBRIN
  • CONGO RED INDICATOR
  • CONGO RED TS
  • CONGO
  • CONGO RED
  • CONGO RED 4B
  • DIRECT RED
  • DIRECT RED C, R, OR Y
  • DIRECT RED 28
  • Disodium 3,3'-[[1,1'-biphenyl]-4,4'-diylbis(azo)]bis(4-aminonaphthalene-1-sulphonate)
  • ERIE CONGO 4B
  • 1-naphthalenesulfonicacid,3,3’-((1,1’-biphenyl)-4,4’-diylbis(azo))bis(4-amino
  • 1-naphthalenesulfonicacid,3,3’-[[1,1’-biphenyl]-4,4’-diylbis(azo)]bis[4-amino
  • 3,3’-(4,4’-biphenylenebis(azo))bis(4-amino-1-naphthalenesulfonicacidisodi
  • atlanticcongored
  • atulcongored
  • azocardredcongo
  • benzocongored
  • brasilaminacongo4b
  • C.I.Directred28
  • c.i.directred28,disodiumsalt
  • C.T.NO,22120
  • cervenkongo
  • cervenprima28
  • congored4bx
  • congoredcr
  • congoredh
  • congoredici
  • congoredl
  • congoredm
  • congoredn
  • congoredr
  • congoredrs
  • congoredw
  • congoredws
  • cottonred4bc
  • cottonred5b
  • cottonredl
  • diacottoncongored
  • directredc
  • DirectredC.R.Y.
  • directreddc-cf