CAS Registry Number

CAS 89-36-1 — 3-Methyl-1-(4-sulfophenyl)-2-pyrazolin-5-one

3-Methyl-1-(4-sulfophenyl)-2-pyrazolin-5-one, also known as **Methyl Orange**, is a synthetic pH indicator dye widely used in acid-base titrations, analytical chemistry, and textile dyeing. Its distinct color change from red to yellow across pH 3.1–4.4 makes it ideal for visualizing pH shifts in laboratories. This chemical has a CAS number of 89-36-1, a molecular formula of C10H10N2O4S, and a molecular weight of 254.26 g/mol. It is stored at ambient conditions but requires careful handling due to its **Danger** classification. Molekula supplies 3-Methyl-1-(4-sulfophenyl)-2-pyrazolin-5-one from research to bulk quantities with full documentation and ISO 9001:2015 traceability.