An SN2 reaction mechanism for hydrolysis of siloxane linkages and the implications for dissolution of quartz

Density functional theory calculations were performed on an extended silicate molecular cluster to test the hypothesis that inclusion of Cl⁻ to charge-balance protonation of bridging O atoms in siloxane bridges, and H₂O attack via an SN2 mechanism, could explain the observed activation energy of quartz dissolution under acidic conditions. The results are consistent with this hypothesis and help explain the observed solution pH and salt-dependence of quartz dissolution rates.