Methyl Red, chemically known as 2-(N,N-dimethyl-4-aminophenyl) azobenzenecarboxylic acid, is a dark red crystalline azo dye widely used as a pH indicator.
Chemical Properties and Color Change
Methyl Red changes color depending on the acidity of the solution: it appears red in acidic conditions below pH 4.4, yellow in alkaline conditions above pH 6.2, and orange in the intermediate pH range. Its pKa value is 5.1.
🧪 Applications
Methyl Red is commonly used as a pH indicator in glucose biosensors for salivary analysis. It is also employed in the detection of carbohydrates and lactic acid. In microbiology, Methyl Red is used for intrageneric differentiation within the Enterobacteriaceae family.
Environmental Use
Methyl Red, along with Murexide, has been investigated as a promising enhancer for the sonochemical destruction of chlorinated hydrocarbon pollutants.
⚠️ Safety
According to the International Agency for Research on Cancer (IARC), Methyl Red is classified as Group 3 – not classifiable as to its carcinogenicity in humans.
