1.06076

Methyl red (C.I. 13020)

pH indicator, ACS, Reag. Ph Eur

• Synonym(s): Methyl red (C.I. 13020), 4-Dimethylaminoazobenzene-2′-carboxylic acid
• Empirical Formula (Hill Notation): C₁₅H₁₅N₃O₂
• CAS Number: 493-52-7
• Molecular Weight: 269.30
• UNSPSC Code: 12352107
• EC Index Number: 207-776-1
• NACRES: NA.05
• MDL number: MFCD00002425

Properties

• Product Name: Methyl red (C.I. 13020), indicator ACS,Reag. Ph Eur
• grade: ACS reagent
• Quality Level: 200
• agency: reag. Ph. Eur., suitable for SM 4500 - NH3
• form: powder, solid
• loss: ≤5% loss on drying, 110°C
• color: red to red-violet
• visual transition interval: 4.4-6.0, red to yellow
• mp: 178-182 °C
• bulk density: 300‑500 kg/m³
• Amax: 427-437 nm (buffer pH 6.2), 523-526 nm (buffer pH 4.5)
• storage temp.: 2-30°C
• SMILES string: N(C)(C)c1ccc(cc1)N=Nc2c(cccc2)C(=O)O
• InChI: 1S/C15H15N3O2/c1-18(2)12-9-7-11(8-10-12)16-17-14-6-4-3-5-13(14)15(19)20/h3-10H,1-2H3,(H,19,20)
• InChI key: CEQFOVLGLXCDCX-UHFFFAOYSA-N

Description

Analysis Note

Identity (UV/VIS-Spectrum): passes test
Appearance: Red to red-violet powder, eventually with granular parts.
Clarity of solution (1 g/l; ethanol): passes test
Melting point (capillary method, temperatur measerment in the heating block): 179 - 182 °C
Transition range: pH 4.4 - pH 6.0 Red - yellow
Absorption maximum (buffer pH 4.5): 523 - 526 nm
Absorption maximum (buffer pH 6.2): 427 - 437 nm
Spec. Absorptivity A 1%/1cm (λ_max; 0.005 g/l; buffer pH 4.5; calculated on anhydrous substance): 1350 - 1500
Spec. Absorptivity A 1%/1cm (λ_max; 0.005 g/l; buffer pH 6.2; calculated on anhydrous substance): 700 - 800
Transition range (according to ACS): passes test
Loss on drying (110 °C): ≤ 5 %

Safety Information

• Storage Class: 11 - Combustible Solids
• wgk: WGK 2
• flash_point_f: Not applicable
• flash_point_c: Not applicable