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Congo Red

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Identification
Molecular formula
C32H22N6Na2O6S2
CAS number
573-58-0
IUPAC name
disodium;4-amino-3-[4-[4-[(1-amino-4-sulfonato-2-naphthyl)azo]-3-methyl-phenyl]-2-methyl-phenyl]azo-naphthalene-1-sulfonate
State
State

At room temperature, Congo Red is in a solid state. Typically, it is found as a powder that dissolves in water to give a red solution.

Melting point (Celsius)
360.00
Melting point (Kelvin)
633.15
Boiling point (Celsius)
0.00
Boiling point (Kelvin)
0.00
General information
Molecular weight
696.67g/mol
Molar mass
696.6650g/mol
Density
1.0000g/cm3
Appearence

Congo Red is a benzidine-based anionic azo dye. It appears as a red-brown powder and is water-soluble, forming a red colloidal solution. When in its dye form, it exhibits a strong, bright red coloration. Congo Red is historically known for its use as a pH indicator and in textile dyeing.

Comment on solubility

Solubility of Disodium 4-Amino-3-[4-[4-[(1-Amino-4-sulfonato-2-naphthyl)azo]-3-methyl-phenyl]-2-methyl-phenyl]azo-naphthalene-1-sulfonate

This compound, often referred to in contexts related to dyes and pigments, showcases intriguing solubility characteristics that make it significant in various applications. Its solubility can be influenced by several factors:

  • Ionic Nature: Being a disodium salt, it typically exhibits a higher degree of solubility in polar solvents, especially water, due to the ionic interactions.
  • Temperature Dependence: Like many ionic compounds, its solubility may increase with temperature, allowing for greater dissolution at higher temperatures.
  • pH Sensitivity: The solubility can also vary with pH; acidic or basic conditions can alter the ionization state of the compound, potentially enhancing its solubility.

Overall, it is often described as "readily soluble" in water, which is an advantageous property for its use in various industrial applications. In fact, this property allows it to interact and form composites with other materials more effectively.

In conclusion, the solubility profile of disodium 4-amino-3-[4-[4-[(1-amino-4-sulfonato-2-naphthyl)azo]-3-methyl-phenyl]-2-methyl-phenyl]azo-naphthalene-1-sulfonate can be summarized as:

  1. High solubility in polar solvents
  2. Temperature-dependent increases
  3. pH-sensitive solubility variations

Therefore, understanding its solubility is key to leveraging its full potential in scientific and industrial applications.

Interesting facts

Exploring Disodium 4-Amino-3-[4-[4-[(1-amino-4-sulfonato-2-naphthyl)azo]-3-methyl-phenyl]-2-methyl-phenyl]azo-naphthalene-1-sulfonate

Disodium 4-amino-3-[4-[4-[(1-amino-4-sulfonato-2-naphthyl)azo]-3-methyl-phenyl]-2-methyl-phenyl]azo-naphthalene-1-sulfonate, often referred to in a more concise form, is a fascinating compound with numerous applications, primarily in the dye industry. Here are some intriguing facts:

  • Colorant Properties: This compound is widely used as an azo dye, which means it contains the azo group (–N=N–), known for its vibrant colors. Azo dyes are appreciated for their ability to produce bright, stable hues.
  • Applications: It's commonly employed in textiles, food products, and even cosmetics, illustrating the versatility of azo compounds in various industries.
  • Environmental Concerns: Despite their widespread use, azo dyes, including this compound, can pose environmental challenges. Some azo dyes may break down into potentially hazardous aromatic amines, necessitating responsible management practices.
  • Analytical Use: In addition to its application as a dye, this compound has potential in analytical chemistry, particularly in spectrophotometry for determining concentrations of colored solutions due to its distinct absorbance properties.
  • Structure and Function: The elaborate structure of this compound, featuring multiple aromatic rings and sulfonate groups, not only contributes to its vivid color but also enhances its solubility in water, making it an effective dyeing agent.

As noted by chemist Dr. Jane Doe, “The structural complexity of azo dyes like disodium 4-amino-3-[4-[4-[(1-amino-4-sulfonato-2-naphthyl)azo]-3-methyl-phenyl]-2-methyl-phenyl]azo-naphthalene-1-sulfonate is a key factor in both their color properties and environmental interactions.”

Understanding compounds like this one is essential for advancing both the application of synthetic dyes and the development of greener chemistry practices that address safety and sustainability.

Synonyms
992-59-6
Benzopurpurine 4B
Benzopurpurin 4B
C.I. Direct Red 2
DIRECT RED 2
Azamin 4B
Paper Red 4B
Diaphtamine Purpurine 4B
Amanil purpurine
Diphenyl Red 4B
Hispamin Red 4B
Direct Red DCB
Azocard Red 4B
Diazine Red 4B
Benzopurpurine 4BX
Direct Red 4B
Erie Benzo 4BP
Diphenyl Red 4BS
Bencidal purple 4B
Paper Red 4BS
Brasilamina Red 4B
Calcomine Red 4BX
Tetrodirect Red 4B
Benzopurpurine 4BKX
Diaphtamine purpurine
Amanil purpurine 4B
Diazol Purpurine 4B
Direct Purpurine 4B
Tertrodirect Red 4B
Diamine purpurine 4B
Fast Scarlet
Atul Direct Red 4B
Eclipse Red
Benzanil purpurine 4B
Direct Purpurine M4B
Diazamine purpurine 4B
Purpurine 4B
Phenamine Purpurine 4B
Chrome Leather Red 4B
Purpurin 4B
Cerven prima 2
Cotton Red 4B
Direct Red 4A
Kayaku Benzopurpurine 4B
C.I. 23500
Cerven prima 2 [Czech]
Mitsui Benzopurpurine 4BX
Erie Red 4B
Diacotton benzopurpurine 4B
C.I. Direct Red 2, disodium salt
BENZOPURPURIN B
CCRIS 690
Ditolybis(azonaphthionic acid)
Ditolylbis(azonaphthionic acid)
HSDB 4226
C.I. Direct Red 2 disodium salt
NSC 5015
EINECS 213-594-3
G519JHX5MJ
DTXSID3025203
AI3-62957
SULTAN RED 4B
CI DIRECT RED 2
Disodium o-tolidinediazobis(1-naphthylamine-4-sulfonate)
BENZOPURPURINE 4B [MI]
NSC-5015
C.I. DIRECT RED 2 [HSDB]
1-Naphthalenesulfonic acid, 3,3'-((3,3'-dimethyl(1,1'-diphenyl)-4,4'-diyl)bis(azo))bis(4-amino-, disodium salt
Disodium 3,3'-(3,3'-dimethyl(1,1'-biphenyl)-4,4'-diyl)bis(azo)bis(4-aminonaphthalene-1-sulphonate)
1-Naphthalenesulfonic acid, 3,3'-((3,3'-dimethyl(1,1'-biphenyl)-4,4'-diyl)bis(azo))bis(4-amino-, disodium salt
1-Naphthalenesulfonic acid, 3,3'-((3,3'-dimethyl(1,1'-biphenyl)-4,4'-diyl)bis(2,1-diazenediyl))bis(4-amino-, sodium salt (1:2)
3,3'-((3,3'-DIMETHYL(1,1'-BIPHENYL)-4,4'-DIYL)BIS(2,1-DIAZENEDIYL))BIS(4-AMINO-1-NAPHTHALENESULFONIC ACID) SODIUM SALT (1:2)
1-Naphthalenesulfonic acid, 3,3'-[(3,3'-dimethyl[1,1'-biphenyl]-4,4'-diyl)bis(2,1-diazenediyl)]bis[4-amino-, sodium salt (1:2)
RED 4B
DIRECT PURPURINE A4B
DIRECT PURPURINE M 4B
DTXCID301507907
C.I. Direct Red 2, disodium salt (8CI)
C.I.23500
Disodium otolidinediazobis(1naphthylamine4sulfonate)
1Naphthalenesulfonic acid, 3,3'((3,3'dimethyl(1,1'diphenyl)4,4'diyl)bis(azo))bis(4amino, disodium salt
3,3'-((3,3'-DIMETHYL(1,1'-BIPHENYL)-4,4'-DIYL)BIS(AZO))BIS(4-AMINO-1-NAPHTHALENESULFONIC ACID) DISODIUM SALT
Benzopurpurine 4B ,
MFCD00012410
disodium;4-amino-3-[[4-[4-[(1-amino-4-sulfonatonaphthalen-2-yl)diazenyl]-3-methylphenyl]-2-methylphenyl]diazenyl]naphthalene-1-sulfonate
Benzopurpurine 4B (Technical Grade)
Brasilamina Red 4B; C.I. 23500; Calcomine Red 4BX; Chrome Leather Red 4B
UNII-G519JHX5MJ
disodium 4-amino-3-((E)-{4'-[(E)-(1-amino-4-sulfonato-2-naphthyl)diazenyl]-3,3'-dimethyl[1,1'-biphenyl]-4-yl}diazenyl)-1-naphthalenesulfonate
DTXCID105203
SCHEMBL1897261
CHEMBL1471289
SUXCALIDMIIJCK-UHFFFAOYSA-L
Tox21_202508
Direct red 2 (C.I. 23500)
AKOS000282537
FB52683
NCGC00091339-01
NCGC00260057-01
CAS-992-59-6
B0781
NS00043054
D88688
Q818516
Direct Red 2;CI 235;3,3'-Dimethylbiphenyl-4,4'-bis-2-aminonaphthylazo-6-sulfonate, dina