methyl red
Chemistry
noun
A dark red, weakly acidic, water-insoluble dye that is the azo compound of dimethylaniline and anthranilic acid and is used (in alcoholic solution) as an acid–base indicator, changing from red to yellow over a pH range of 4.2 to 6.3; (CH3)2NC6H4NNC6H4COOH.
Origin
Early 20th century; earliest use found in Journal of the Chemical Society. From methyl + red, after German Methylrot.