IUPAC Name: (4E)-4-[(2-Hydroxy-5-methylphenyl)hydrazinylidene]-3-oxonaphthalene-1-sulfonic acid
Molecular Formula: C₁₇H₁₄N₂O₅S
Molecular Weight: 358.37 g/mol
Canonical SMILES: O=S(=O)(O)c1c2c(c(\N=N\c3c(O)ccc(C)c3)c(O)c1)cccc2
InChI: InChI=1/C17H14N2O5S/c1-10-6-7-14(20)13(8-10)18-19-17-12-5-3-2-4-11(12)16(9-15(17)21)25(22,23)24/h2-9,20-21H,1H3,(H,22,23,24)/b19-18+
Mol File: 3147-14-6.mol
EINECS: 221-563-0
Product Categories: Organics;Analytical Chemistry; Azo Compounds; Chelating Reagents; Naphthylazo Compounds
Storage temperature: Store at RT.
XLogP3-AA: 2.1
H-Bond Donor: 3
H-Bond Acceptor: 7
Rotatable Bond Count: 3
Tautomer Count: 23
Exact Mass: 358.062342
Topological Polar Surface Area: 116
Heavy Atom Count: 25
Complexity: 694
Melting Point: 330 °C(lit.)
Atmospheric OH Rate Constant: 2.05E-11 cm³/molecule-sec at 25 °C
Index of Refraction: 1.682
Molar Refractivity: 91.477 cm³
Molar Volume: 241.377 cm³
Polarizability: 36.265×10^-24 cm³
Surface Tension: 61.691 dyne/cm
Density of Calmagite (CAS NO.3147-14-6): 1.485 g/cm³

 Calmagite (CAS NO.3147-14-6) is a complexometric indicator used in analytical chemistry to identify the presence of metal ions in solution. It is often used in conjunction with EDTA, a stronger metal binding agent.

Hazard Codes: Xi
Risk Statements: 36/37/38
 R36/37/38: Irritating to eyes, respiratory system and skin.
Safety Statements: 26-36 
S26: In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. 
S36: Wear suitable protective clothing.
WGK Germany of Calmagite (CAS NO.3147-14-6): 3

  Calmagite (CAS NO.3147-14-6), its Synonyms are 1-Naphthalenesulfonic acid, 3-hydroxy-4-((2-hydroxy-5-methylphenyl)azo)- ; 1-Naphthalenesulfonic acid, 3-hydroxy-4-((6-hydroxy-m-tolyl)azo)- (8CI) ; 1-Naphthalenesulfonic acid, 3-hydroxy-4-(2-(2-hydroxy-5-methylphenyl)diazenyl)- ; 3-Hydroxy-4-((6-hydroxy-m-tolyl)azo)-1-naphthalenesulfonic acid ; 3-Hydroxy-4-(6-hydroxy-m-tolylazo)naphthalene-1-sulphonic acid . It is dark brown crystalline powder.