Molecule structure of Ponceau S (CAS NO.6226-79-5):

IUPAC Name: Tetrasodium (4Z)-3-oxo-4-[[2-sulfonato-5-[(4-sulfonatophenyl)diazenyl]phenyl]hydrazinylidene]naphthalene-2,7-disulfonate 
Molecular Weight: 760.56876 [g/mol]
Molecular Formula: C₂₂H₁₂N₄Na₄O₁₃S₄ 
Density 1.01 g/mL at 20 °C
Refractive Index: n20/D 1.338
Storage Temp.: store at RT.
Water Solubility: 10 g/L
Stability: stable. incompatible with strong oxidizing agents.
H-Bond Donor: 1
H-Bond Acceptor: 17
Rotatable Bond Count: 4
Tautomer Count: 3
Exact Mass: 759.887448
MonoIsotopic Mass: 759.887448
Topological Polar Surface Area: 295
Heavy Atom Count: 47
Canonical SMILES: C1=CC(=CC=C1N=NC2=CC(=C(C=C2)S(=O)(=O)[O-])NN=C3C4=C(C=C(C=C4)S(=O)(=O)[O-])C=C(C3=O)S(=O)(=O)[O-])S(=O)(=O)[O-].[Na+].[Na+].[Na+].[Na+]
Isomeric SMILES: C1=CC(=CC=C1N=NC2=CC(=C(C=C2)S(=O)(=O)[O-])N/N=C\3/C4=C(C=C(C=C4)S(=O)(=O)[O-])C=C(C3=O)S(=O)(=O)[O-])S(=O)(=O)[O-].[Na+].[Na+].[Na+].[Na+]
InChI: InChI=1S/C22H16N4O13S4.4Na/c27-22-20(43(37,38)39)10-12-9-16(41(31,32)33)6-7-17(12)21(22)26-25-18-11-14(3-8-19(18)42(34,35)36)24-23-13-1-4-15(5-2-13)40(28,29)30;;;;/h1-11,25H,(H,28,29,30)(H,31,32,33)(H,34,35,36)(H,37,38,39);;;;/q;4*+1/p-4/b24-23?,26-21-;;;;
InChIKey: LZYGEJPERQQCIY-STNZDNLRSA-J
EINECS: 228-319-2
Product Categories: Organics; P; Stains and Dyes; Stains&Dyes, A to

 Ponceau S (CAS NO.6226-79-5) may be used to prepare a stain for rapid reversible detection of protein bands on nitrocellulose or PVDF membranes (Western blotting), as well as on cellulose acetate membranes.

Hazard Codes: Xi
Risk Statements: 36/37/38 
R36/37/38:Irritating to eyes, respiratory system and skin.
Safety Statements: 26-36-37/39 
S26: In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. 
S36:Wear suitable protective clothing. 
S37/39:Wear suitable gloves and eye/face protection.
WGK Germany: 3
RTECS: QJ6600000
HS Code: 32041200

 Ponceau S (CAS NO.6226-79-5) is also named as 2-Hydroxy-1-((4((4-sulfophenyl)azo)-2-sulfophenyl)azo)naphthalene-3,6-disulfonic acid, tetrasodium salt ; C.I. 27195 ; C.I. Acid Red 112 ; NSC 16216 ; Ponceau Red S ; Ponceau S Extra ; 2,7-Naphthalenedisulfonic acid, 3-hydroxy-4-((2-sulfo-4-((4-sulfophenyl)azo)phenyl)azo)-, tetrasodium salt ; 2,7-Naphthalenedisulfonic acid, 3-hydroxy-4-(2-(2-sulfo-4-(2-(4-sulfophenyl)diazenyl)phenyl)diazenyl)-, sodium salt (1:4) ; C.I. Acid Red 112, tetrasodium salt (8CI) ; Tetrasodium 3-hydroxy-4-(2-sulphonato-4-(4-sulphonatophenylazo)phenylazo)naphthalene-2,7-disulphonate . Ponceau S (CAS NO.6226-79-5) is red powder.