| Abstract
| - Previous work by Kirby and co-workers revealed a significant acceleration of the rate of hydrolysisof p-nitrophenyl phosphate by added dipolar solvents such as DMSO. Activation parameters andkinetic isotope effects have been measured to ascertain the origin of this effect. The generality ofthis phenomenon was examined with a series of esters with more basic leaving groups.Computational analyses of the effects of desolvation of dianionic phosphate monoesters were carriedout, and the possible effect of the transfer from water to the active site of alkaline phosphatasewas modeled. The results are consistent with a desolvation-induced weakening of the P−O esterbond in the ground state. Other aryl phosphate esters show similar rate accelerations at highfractions of DMSO, but phenyl and methyl phosphates do not, and their hydrolysis reactions areactually slowed by these conditions.
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