Kinetic characteristics of the ring-chain tautomeric equilibria of 2,3,3-trimethyl-1-aryl-2-hydroxy-5-pyrrolidones
The kinetics of the ring—chain tautomeric equilibria of a number of p-substituted 2,3,3-trimethyl-1-aryl-2-hydroxy-5-pyrrolidones in 50% aqueous pyridine were studied by dynamic PMR spectroscopy, and the effect of substituents on the kinetic parameters of this process was determined. The free energies of activation (ΔG≠) decrease regularly on passing from electron-donor to electron-acceptor substituents. A good correlation between ΔG≠ and the σ+ and σ substituent constants is observed. On the basis of the data obtained, it was concluded that the ratedetermining step in the process is detachment of a proton under the influence of the base to give the corresponding anion.
KeywordsSpectroscopy Free Energy Organic Chemistry Pyridine Kinetic Parameter
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