Medium Effect on the Acid Dissociation Constants of Some Heterocyclic Azo Compounds

1999 ◽  
Vol 44 (3) ◽  
pp. 451-455 ◽  
Author(s):  
Said A. Ibrahim ◽  
Nasr M. Rageh ◽  
Ahmed A. Mohamad ◽  
Youssif H. Ebead
Keyword(s):  
Dissociation Constants ◽  
Acid Dissociation ◽  
Medium Effect ◽  
Azo Compounds ◽  
Acid Dissociation Constants

Medium Effect on the Acid Dissociation Constants of 2,2‘,6‘,2‘ ‘-Terpyridine

2003 ◽  
Vol 48 (1) ◽  
pp. 29-31 ◽  
Author(s):  
Mohamed A. El-Gahami ◽  
Said A. Ibrahim ◽  
Dina M. Fouad ◽  
Abbas M. Hammam
Keyword(s):  
Dissociation Constants ◽  
Acid Dissociation ◽  
Medium Effect ◽  
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.

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