Chemistry on the decay of the phenoxy radical from butylated hydroxytoluene

Decay of unstable 2,6‐di‐tert‐butyl‐4‐methylphenoxy radical (2) was investigated in various solvents. Radical 2 was conveniently generated by dissociation of bis(methylcyclohexadienone) (1a), unstable dimer of 2, in solution. The products were butylated hydroxytoluene (3), 1,2‐bis(4‐hydroxyphenyl)ethane (7), 4,4′‐stilbenequinone (8), and 4‐(4‐hydroxybenzyl)cyclohexadienone (5). Unidentified products also were formed. The formation of 5 was favored in polar solvents, but was not subject to catalysis with Et3N or HCl. In contrast, the rates of formation of 7 and 8 appeared to be independent of solvent polarity. The mechanism of formation of the dimeric productsvia reactive intermediate quinone methide 4, generated from 2 by disproportionation, is discussed. Gradual disintegration of 5 in solution into 3 and 4 was investigated.