The chemistry of reactive lignin intermediates. Part II. Addition reactions of vinyl-substituted quinone methides in aqueous solution

The rate equation describing the pH dependence of addition reactions of the quinone methide 4-allylidene-2-methoxycyclohexa-2,5-dienone (IIb)(QM) in aqueous solution has the form v={k0+kOH–[OH–]+kH3O+[H3O+]}[QM]. The values of the individual rate constants are reported. Some data for the analogous 2,6-dimethoxy-compound (IIc) are also reported. Mechanisms of addition of hydroxy-compounds are discussed.