Reactivity of butylated hydroxytoluene.

Butylated hydroxytoluene (BHT) is a synthetic antioxidant that is widely used as an additive in foodstuffs to prevent spoiling. The physical-chemical properties of BHT and many related phenols have been examined previously although the mechanisms by which it exerts its antioxidant properties are poorly understood. The reactivity of BHT with singlet oxygen [O2(1 delta g)] and a number of radical species has been examined using the techniques of time resolved luminescence and pulse radiolysis. In benzene solution BHT reacted with O2(1 delta g) at a bimolecular rate constant of 1.3 x 10(6)M-1s-1. The one-electron oxidized, phenoxyl type BHT radical was generated using pulse radiolysis and the absorption spectrum showed a maximum at 400 nm. BHT reacts slowly with many radical species and upper limits for the bimolecular rate constant for reaction with several electron transfer processes are presented. The antioxidant role of BHT is discussed in terms of its reactivity, localization, and stability.