Computational studies of site-specific hydroxyl radical attack on substituted phenols mediated by chloride.

D.W. King, J.M. St.Clair

Lab experiments have clearly demonstrated that the site-specific attack of hydroxyl radicals on substituted phenols is mediated by the presence of chloride or sulfate anions. In the presence of anions the ·OH will be rapidly scavenged to form several Cl-containing radical intermediates. We have explored this system using ab initio molecular orbital calculations at the 6-31G** level. The ·OH forms a ·OHCl- intermediate, as opposed to ·OHCl- as previously expected. ·OHCl- and ·Cl appear to provide site-specific attack on phenolic protons, yielding a phenolic radical. The phenolic radical reacts at the ortho carbon to form a dimer, terminating the radical.