Methyl Red sodium salt is used as a pH indicator. In microbiology, it is used to make agar plates in bacteriology. Further, it is used as a coloring agent and also finds use in mouthwash, toothpaste and in cosmetics. It is also employed as a rocket propellant. In addition to this, it is used in the preparation of reversible stain for rapid detection of stained cells in each specimen.
Methyl red sodium salt is the sodium salt of methyl red synthetic dye, which belongs to the azo group of dyes.
Methyl Red is a pH indicator and it changes color at a pH of 5.5.
It can be precipitated from aqueous solution as the free acid which is recrystallised from 95% EtOH, then reconverted to the sodium salt. In H2O it is pink at pH 4.2 and yellow at pH 6.2 and has at 437nm.
