1.01340

Congo red (C.I. 22120)

pH indicator, Reag. Ph Eur

• Synonym(s): Congo red (C.I. 22120)
• Empirical Formula (Hill Notation): C₃₂H₂₂N₆Na₂O₆S₂
• CAS Number: 573-58-0
• Molecular Weight: 696.66
• UNSPSC Code: 12352107
• EC Index Number: 209-358-4
• NACRES: NA.21
• MDL number: MFCD00004028

Properties

• Product Name: Congo red (C.I. 22120), indicator Reag. Ph Eur
• agency: reag. Ph. Eur.
• Quality Segment: 200
• vapor pressure: <1 Pa
• form: powder
• potency: 143 mg/kg LD₅₀, oral (Rat)
• loss: ≤5% loss on drying, 110°C
• color: almost clear to slightly turbid red, 1.0g/L;water, red-brown
• pH: 6.7 (20 °C, 10 g/L in H₂O)
• mp: >360 °C
• bulk density: 600‑700 kg/m³
• storage temp.: 2-30°C
• SMILES string: [Na+].[Na+].[S](=O)(=O)([O-])c1c2c(c(c(c1)N=Nc3ccc(cc3)c4ccc(cc4)N=Nc5c(c6c(c(c5)[S](=O)(=O)[O-])cccc6)N)N)cccc2
• InChI: 1S/C32H24N6O6S2.2Na/c33-31-25-7-3-1-5-23(25)29(45(39,40)41)17-27(31)37-35-21-13-9-19(10-14-21)20-11-15-22(16-12-20)36-38-28-18-30(46(42,43)44)24-6-2-4-8-26(24)32(28)34;;/h1-18H,33-34H2,(H,39,40,41)(H,42,43,44);;/q;2*+1/p-2
• InChI key: IQFVPQOLBLOTPF-UHFFFAOYSA-L

Description

Analysis Note

Appearance: Red-brown to brownishred powder, eventually with granular parts.
Appearance of solution (1.0 gr/l; water): Almost clear to slightly turbid, red
Transition range: pH 3.0 - pH 5.2violet - orange-red
Loss on drying (110 °C): ≤ 5 %
Sensitivity test: passes test

Safety Information

• pictograms: GHS08
• signalword: Danger
• hcodes: H350 - H361d
• pcodes: P201 - P202 - P280 - P308 + P313 - P405 - P501
• Hazard Classifications: Carc. 1B - Repr. 2
• Storage Class: 6.1C - Combustible, acute toxic Cat.3 / toxic compounds or compounds which causing chronic effects
• wgk: WGK 3