135303-18-3Relevant academic research and scientific papers
Thermodynamic and kinetic acidities of N-(substituted benzyl) 4-phenylacetylpyridinium cations in aqueous solution
Bunting, John W.,Aubin, P. Philippe
, p. 945 - 948 (2007/10/02)
The pKa values for the deprotonation of a series of eight 1-(X-benzyl)-4-phenylacetylpyridinium cations (6) have been measured in aqueous solutions of ionic strength 0.1 at 25 deg C: pKa = -0.18? + 8.91.The pseudo-first-order rate constants for deprotonation of these carbon acids have been measured over the range pH = 11-13, and have been found to display kinetic saturation effects that are consistent with the addition of hydroxide ion to the carbonyl group (pKz) as the product of kinetic control upon basification of neutral aqueous solutions of these pyridinium cations, with the subsequent transformation of this anionic hydrate to the thermodynamically more stable enolate conjugate base.Analysis of the pH-rate profiles gives substituent effects upon pKz (ρ = -0.19) and upon the second-order rate constant (kOH(ρ = 0.09)) for deprotonation of 6 by hydroxide ion. Key words: carbon acids, deprotonation, pKa, kinetics, substituent effects.
