Kinetics of the reaction of phenyl picrates with phenoxide ions in water. Concerted or stepwise?

A kinetic study is reported of the exchange reactions of substituted phenoxide ions with some ring‐substituted 2,4,6‐trinitrophenyl ethers in water. The βrønsted diagrams formed by plotting log k, where k is the second‐order rate constant for reaction, versus pKa show a distinct change in slope when ΔpKa = 0 (ΔpKa being the difference in pKa values of the leaving group and nucleophile). This is consistent with a two‐step process involving a discrete σ‐adduct intermediate rather than a concerted process. From the measured β values for forward and reverse processes, the overall effective charge map has been constructed. Copyright © 2013 John Wiley & Sons, Ltd. The exchange reaction of phenoxide ions with phenyl 2,4,6‐trinitrophenyl ethers is a stepwise rather than concerted process. Kinetics of the Reaction of Phenyl Picrates with Phenoxide Ions in Water. Concerted or Stepwise? Michael Crampton and Ian Robotham.