CA Index Name: Benzenesulfonic acid, 4-[2-[4-(dimethylamino)phenyl]diazenyl]-, sodium salt (1:1)
Other Names: Benzenesulfonic acid, 4-[[4-(dimethyla-mino)phenyl]azo]-, sodium salt; Benzenesulfonic acid, p-[[p-(dimethylamino)phenyl]azo]-, sodium salt; Orange III; 4-Dimethylaminoazobenzene-4'-sulfonic acid sodium salt; Acid Orange 52; Albion Methyl Orange; C.I. 13025; C.I. Acid Orange 52; Diazoben; Eniamethyl Orange; Gold Orange; Helianthine; Helianthine B; KCA Methyl Orange; Methyl Orange B; Methyl Orange; Orange 3; Sodium 4'-(dimethylamino)azobenzene-4-sulfonate; Sodium 4-(dimethylamino)azobenzene-4'-sulfonate; Sodium 4-[4-(dimethylamino)phenylazo]benzenesulfo-nate; Sodium p-[[p-(dimethylamino)phenyl]azo]benzene-sulfonate; Sodium p-dimethylaminoazobenzenesulfo-nate; Tropaeolin D
Merck Index Number: 6105
Chemical / Dye Class: Azo
Molecular Formula: C14H14N3NaO3S
Molecular Weight: 327.33
Physical Form: Orange-yellow powder or crystals
Solubility: Slightly soluble in water, more soluble in hot water; practically insoluble in ethanol
Melting Point: > 300 °C
pH Range: 3.0-4.4
Color Change at pH: Red (3.0) to yellow (4.4)
pKa: 3.76, 3.40
Absorption (λmax): 507 nm
Synthesis: Synthetic methods
Staining Applications: Albumin; leukocytes; nucleic acids; protein; nails; skin; hairs
Biological Applications: Detecting microorganisms; treating dermatological diseases, vaginal affections; dental materials; wound dressing materials
Industrial Applications: Thin films; nanoparticles; liquid crystals; sol-gel matrix; waveguides; paints; glass
Safety / Toxicity: Carcinogenicity; genotoxicity; mutagenicity
Certification / Approval: Certified by Biological Stain Commission (BSC)