Oxidation of Thiols. IV. The Effect of Substituents on Ionization and Hexacyanoferrate (III) Oxidation of Monothiodiacylmethane

Ionization constants, pKa, for a set of six monothiodiacylmethanes have been determined in 50 vol% ethanol-water mixture at 25°±0.1. Excellent linear correlations are obtained when pKa values are plotted against the substituent constant, σx, and the polar substituent constant, σ*xC6H4, for substitut...

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Bibliographic Details
Published inChemical & pharmaceutical bulletin Vol. 27; no. 3; pp. 620 - 624
Main Authors AL-HAJJAR, FAROUK H., KASSIM, AHMAD Y.
Format Journal Article
LanguageEnglish
Published Tokyo The Pharmaceutical Society of Japan 1979
Japan Science and Technology Agency
Subjects
linear free energy relationship
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Summary:Ionization constants, pKa, for a set of six monothiodiacylmethanes have been determined in 50 vol% ethanol-water mixture at 25°±0.1. Excellent linear correlations are obtained when pKa values are plotted against the substituent constant, σx, and the polar substituent constant, σ*xC6H4, for substituted phenyl groups. The regression lines are : pKa=8.00-1.47 σx and pKa=8.92-1.195 σ*xC6H4, respectively. The pKa values are also correlated with the extended Hammett equation. The correlation follows the equation : pKa=7.717-1.330σI, x-1.248σR, x The rate of the oxidation of (Ie) with hexacyanoferrate (III) was discussed at different pH values.
ISSN:0009-2363
1347-5223
DOI:10.1248/cpb.27.620