Abstract
The hydroxylation of fluorobenzene and toluene and the attempted hydroxylation of anisole, nitrobenzene, and benzonitrile by SO/sub 4/./sup -/ has been investigated. Fluorobenzene forms almost exclusively phenol and p-fluorophenol and toluene forms o- and p-cresol, bibenzyl, benzyl alcohol, and benzaldehyde. The proportions of these products depend on oxidizing metal salts and pH. The phenol isomer distribution is consistent with a nucleophilic attack by H/sub 2/O at the ..cap alpha.. and para positions of the radical cation. SCF-MO calculations (INDO) of the radical cations show the highest positive charge at the ..cap alpha.. and para positions. The results show that in the homolytic hydroxylation of fluorobenzene and toulene a reversible acid-catalyzed dehydration will lead to an isomerization of the initially formed hydroxycyclohexadienyl radicals. The absence of hydroxylation of nitrobenzene, benzonitrile, and anisole is probably due to the smaller positive charges at the ring carbons of the radical cations of these aromatics as compared to toluene and fluorobenzene radical cation.
Published Version
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