Shukla, J. P. published the artcileProtolytic equilibria of several 4-acyl-substituted 1-phenyl-3-methylpyrazol-5-ones in dioxane-water mixtures, Category: pyrazoles-derivatives, the main research area is ionization constant pyrazolone acyl derivative; solvent effect ionization acylpyrazolone; thermodn ionization acylpyrazolone; substituent effect ionization acylpyrazole.
Thermodn. proton ionization constants, pKa, of several 4-acyl-substituted pyrazol-5-ones I [R = CF3, Me, (CH2)4Me] were determined in various dioxane-water mixtures at 25 and 35 ± 0.1°. The pKa values were determined by glass-electrode potentiometry and refined by computer. Both extrapolation and least-squares methods were used to obtain pKa values in pure water. All three acyl derivatives are weak monoprotic acids with pKa values between 2.5 and 3.9, increasing in the order stated. The pKa values do not vary linearly with the reciprocal of the dielec. constant of the medium; however, a plot of pKa vs. the mole fraction of dioxane is linear at a given temperature Values of standard free energy, enthalpy, and entropy changes associated with their protolytic equilibrium were also calculated Temperature, medium and substituent effects are briefly discussed.
Journal of Physical Organic Chemistry published new progress about Enolization. 1691-93-6 belongs to class pyrazoles-derivatives, name is 5-Methyl-2-phenyl-4-(2,2,2-trifluoroacetyl)-1H-pyrazol-3(2H)-one, and the molecular formula is C12H9F3N2O2, Category: pyrazoles-derivatives.
Referemce:
Pyrazole – Wikipedia,
Pyrazoles – an overview | ScienceDirect Topics