Monographs: Pharmaceutical substances: Butylhydroxytoluenum - Butylated hydroxytoluene

C₁₅H₂₄O

Relative molecular mass. 220.4

Chemical name. 2,6-Di-tert-butyl-p-cresol; 2,6-bis(1,1-dimethylethyl)-4-methyl-phenol; CAS Reg. No. 128-37-0.

Other name. BHT.

Description. Colourless crystals or a white or almost white, crystalline powder; odour, faint and characteristic.

Solubility. Practically insoluble in water; freely soluble in ethanol (~750 g/l) TS, acetone R, ether R, and arachis oil R.

Category. Antioxidant.

Storage. Butylated hydroxytoluene should be kept in a well-closed container, protected from light.

Requirements

Identity tests

A. Dissolve 0.1 g in 10 ml of ethanol (~750 g/l) TS and add 4 ml of sodium tetraborate (10 g/l) TS and a few crystals of 2,6-dichloroquinone chlorimide R; no more than a faint blue colour is produced (distinction from butylated hydroxyanisole).

B. Dissolve 10 mg in 2 ml of ethanol (~750 g/l) TS. Add 1 ml of testosterone propionate/ethanol TS and 2 ml of sodium hydroxide (~80 g/l) TS. Warm in a water-bath at 80 °C for 10 minutes, and allow to cool; a blue colour is produced.

Congealing temperature. Not lower than 69.2 °C.

Sulfated ash. Not more than 1.0 mg/g.

Acid value. Not more than 0.05.