Journals / Turkish Journal of Chemistry / 2014 / Cilt: 38 - Sayı: 1
NH-acidities and Hammett correlation of 3-para substituted phenyl-1,2,4-oxadiazol-5(4H)-ones and 1,2 λ 43,5-oxathiadiazole 2-oxides in nonaqueous media
- Journal
- Turkish Journal of Chemistry
- Pages
- 56–62
- DOI
- —
Abstract
NH acidities of some 3-(p-substitutedphenyl)-1,2,4-oxadiazol-5(4H)-ones and 4-(p-substitutedphenyl)-1,2 l43,5-oxathiadiazole 2-oxides were determined in methanol by means of potentiometric titration with sodium methoxide. pKa values of the title compounds calculated from the potentiometric data were interpreted on the basis of structural effects caused by para-substituted groups on the phenyl ring by plotting pKa values versus Hammett sp+ constants, which gave excellent linear correlations.
Özet
NH acidities of some 3-(p-substitutedphenyl)-1,2,4-oxadiazol-5(4H)-ones and 4-(p-substitutedphenyl)-1,2 l43,5-oxathiadiazole 2-oxides were determined in methanol by means of potentiometric titration with sodium methoxide. pKa values of the title compounds calculated from the potentiometric data were interpreted on the basis of structural effects caused by para-substituted groups on the phenyl ring by plotting pKa values versus Hammett sp+ constants, which gave excellent linear correlations.