Hydrolytic Dephosphorylation of an Aryl Phosphoramidate

Abstract

Mono-2-NO₂-4-CI phenyl phosphoramidate has been kinetically
pursued for its hydrolysis at 50 ± 5°C and Allen's modified method
has been employed for quantitative results. First order rate coefficients
have been calculated in the entire acid range, 0.01-7.0 M
HCI ionic strength studies lead to the fixed contribution of the
undissociated form between 0.5-3.0 M, while the monoprotonated
form solely contributed in the higher acid media, 4.0-7.0 M HCI.
Beyond 4.0 M, water activity governs the rate of hydrolysis and a
maximum number of three water molecules, derived from both
Yates and McCleland correlation as well as Bronsted-Bjerrum equation,
have been arrived at to transform the ester into its transition
state. Solvent effect, concentration and Arrhenius parameters have
been used to confirm the above results.