Methyl Red 25g


Methyl red (2-(N,N-dimethyl-4-aminophenyl) azobenzenecarboxylic acid), also called C.I. Acid Red 2, is an indicator dye that turns red in acidic solutions. It is an azo dye, and is a dark red crystalline powder. Methyl red is a pH indicator;

9 in stock (can be backordered)

SKU: ZA.002.746 Category:


Catalogue Number ZA.002.746
Synonyms 4-Dimethylaminoazobenzene-2′-carboxylic acid


Product Information
CAS number 493-52-7
EC number 207-776-1
Grade ACS,Reag. Ph Eur
Hill Formula C₁₅H₁₅N₃O₂
Molar Mass 269.31 g/mol
HS Code 2927 00 00
Structure formula Image Structure formula Image
Quality Level MQ200


Physicochemical Information
Melting Point 178 – 182 °C
Bulk density 300 – 500 kg/m3


Safety Information according to GHS
Storage class 10 – 13 Other liquids and solids
WGK WGK 2 obviously hazardous to water
Disposal 3
Relatively unreactive organic reagents should be collected in container A. If halogenated, they should be collected in container B. For solid residues use container C.


Safety Information
Hazard Symbols Hazard SymbolsDangerous for the environment
Categories of danger dangerous for the environment
R Phrase R 51/53
Toxic to aquatic organisms, may cause long-term adverse effects in the aquatic environment.
S Phrase S 61
Avoid release to the environment. Refer to special instructions/ Safety data sheets.


Storage and Shipping Information
Storage Store at +5°C to +30°C.


Transport Information
Declaration (railroad and road) ADR, RID Kein Gefahrgut
Declaration (transport by air) IATA-DGR No Dangerous Good
Declaration (transport by sea) IMDG-Code No Dangerous Good


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 (λmax; 0.005 g/l; buffer pH 4.5; calculated on anhydrous substance) 1350 – 1500
Spec. Absorptivity A 1%/1cm (λmax; 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 %


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