ChemInform Abstract: ACID DISSOCIATION CONSTANTS AND RATES AS STUDIED BY ULTRASONIC ABSORPTION

1977 ◽  
Vol 8 (8) ◽  
pp. no-no
Author(s):  
L. W. GREEN ◽  
P. KRUUS ◽  
M. J. MCGUIRE
Keyword(s):  
Dissociation Constants ◽  
Acid Dissociation ◽  
Ultrasonic Absorption ◽  
Acid Dissociation Constants

Acid dissociation constants and rates as studied by ultrasonic absorption

1976 ◽  
Vol 54 (20) ◽  
pp. 3152-3162 ◽  
Author(s):  
Larry W. Green ◽  
Peeter Kruus ◽  
M. Jacqueline McGuire
Keyword(s):  
Rate Constant ◽  
Dissociation Constants ◽  
Acid Dissociation ◽  
Acid Solutions ◽  
Ultrasonic Absorption ◽  
Absorption Data ◽  
Acid Dissociation Constants ◽  
Density Data ◽  
Sulfuric Acid Solutions ◽  
Experimental Density

Experimental ultrasonic absorption data on solutions of H2SO4 and H3PO4 are interpreted in terms of proton transfer equilibria. The acid dissociation constants obtained are compared with those obtained using other methods and are shown to be consistently lower. A model is proposed to explain this in terms of ΔVθ and ΔHθ involved in the steps leading to recombination of the proton with the anion. This model is supported by the values of the reaction distance parameters calculated from the value of the rate constant obtained for the recombination rate. The accuracy of this rate constant is dependent on the accuracy of the ΔVθ value used for the equilibrium. Experimental density data are presented here as an aid in determining ΔVθ. Problems involving activity coefficients in such solutions are discussed in the course of checking the values used for species present in sulfuric acid solutions.

Substituent effects on polarographic reduction of some photographic color intermediates

1976 ◽  
Vol 54 (8) ◽  
pp. 1205-1210 ◽  
Author(s):  
Ahmad S. Shawali ◽  
Bahgat E. El-Anadouli
Keyword(s):  
Dissociation Constants ◽  
Substituent Effects ◽  
Protonated Form ◽  
Acid Dissociation ◽  
Polarographic Reduction ◽  
Substituent Constant ◽  
Acid Dissociation Constants ◽  
Controlled Potential Electrolysis ◽  
Half Wave ◽  
Controlled Potential

Polarographic reduction of two series of benzoylacetanilides has been investigated in 40% (by volume) ethanolic Britton–Robinson buffers. One series (A) contains substituents on the anilide moiety, and the second (B) has substituents on both the anilide and benzoyl moieties. Polarographic controlled-potential electrolysis data indicate that the electroactive species in both series is the protonated form (ArCOCH2CONHAr′)H+. The reduction half-wave potentials of anilides of series A were found to be independent of the nature of the substituent, whereas those of series B show a good linear relationship when plotted vs. the σ substituent constant of the substituent on the benzoyl moiety (ρ = 0.284, r = 0.995). Values of the acid dissociation constants of the keto (K1) and enol (K2) tautomers of the anilides of series A were calculated; unlike their E1/2 values, the pK1 data show a linear correlation with the Hammett substituent constant, σ. The pK2 values show, however, little variation with σ.

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