Substituent effects on acid dissociation constants of N,N-substituted dithiocarbamic acids

1973 ◽  
Vol 45 (2) ◽  
pp. 363-367 ◽  
Author(s):  
Vernon L. Frampton ◽  
William J. Evans ◽  
James C. Kuck
Keyword(s):  
Dissociation Constants ◽  
Substituent Effects ◽  
Acid Dissociation ◽  
Acid Dissociation Constants

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.

Preparation and nuclear magnetic resonance studies of diaryloxytriphenylphosphoranes. Correlation of substituent effects with 31P N.M.R. chemical shifts

1984 ◽  
Vol 37 (12) ◽  
pp. 2447 ◽  
Author(s):  
Mv Itzstein ◽  
ID Jenkins
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Dissociation Constants ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Acid Dissociation ◽  
Linear Free Energy Relationship ◽  
Acid Dissociation Constants ◽  
Magnetic Resonance Studies ◽  
Linear Free Energy ◽  
Electron Donating Groups

Triphenylphosphine and diisopropyl azodicarboxylate react with phenols in tetrahydrofuran or chloroform at 0° to give diaryloxytriphenylphosphoranes. A linear free-energy relationship has been found between the 31P n.m.r. chemical shifts of many of these phosphoranes and the acid dissociation constants of the corresponding phenols. In general, electron-withdrawing groups on the phenol result in downfield 31P n.m.r. chemical shifts, while electron donating groups result in up-field shifts.

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