Methyl red is a high-grade reagent supplied by Micromaster. Few other chemical names used to denote this reagent include, O-Methyl red, Acid Red 2 and Cerven methylova. It is available in the form of a reddish-violet odourless solid. It can be prepared by diazotization of anthranilic acid, followed by reaction with dimethylaniline. Methyl red is insoluble in water but soluble in very hot acetone, benzene, chloroform, acetic acid, alcohol, lipids and slightly soluble in petroleum ether. It is stable if stored according to the recommended conditions. If exposed to excessive heat or in case of burning, it can generate hazardous decomposition products like nitrogen oxides. Methyl red is incompatible with strong oxidising agents. It is advisable to avoid dust formation and to store this reagent away from excessive heat. It is slightly harmful if inhaled, ingested or absorbed through skin as it may cause irritation.

• CAS No. 493-52-7
• Quantity provided: 100 g/pack
• Molecular formula: C₁₅H₁₅N₃O₂
• Molecular weight: 269.304 g/mol

Methyl red is an azo dye which is most commonly used as a pH indicator. It is red in colour for pH under 4.4, yellow in colour for pH over 6.2, and orange in between 4.4 and 6.2. Methyl red displays pH dependent photochromism, with protonation causing it to adopt a hydrazone/quinone structure and it has a special use in histopathology for showing acidic nature of tissue and presence of organisms with acidic natured cell walls. In microbiology, methyl red is the main component of the methyl red test (MR test) which is used to identify bacteria producing stable acids by mechanisms of mixed acid fermentation of glucose.