Definition of methyl orange in English:

methyl orange


  • An orange crystalline dye that is the sodium salt of the azo compound of dimethylaniline and sulphanilic acid and is chiefly used as an acid–base indicator, changing from red to yellow-orange over a pH range of 3.1 to 4.4; (CH ₃) ₂ NC ₆ H ₄ N=NC ₆ H ₄ SO ₃ Na.


Late 19th century.