Temperature-Dependent Acid Dissociation Constants (Ka , ΔHa , ΔSa ) for a Series of Nitrogen-Substituted Hydroxamic Acids in Aqueous Solution
The acid dissociation constants (Ka) of a series of eight substituted N-phenylacetohydroxamic acids, CH3C—(O)N(OH)C6H4X (X = H, 4-CH3, 4-Cl, 4-I, 3-I, 3-CN, 4-CN, 4-C(O)CH3), have been determined in aqueous solution (I = 2.0) for a range of temperatures. The pKa data at 25 °C exhibit a small variation with the substituent X in the direction expected according to their Hammett substituent constants (ρ ≈ 0.1). These small variations in pKa values are due to compensating trends in ΔHa and ΔSa, which show significant variation with substituent. These results are discussed in terms of the substituent's influence on hydroxamate anion-solvent interactions and the relative influence on pKa of a substituted phenyl group attached to the C or N end of the hydroxamate moiety. © 1982, American Chemical Society. All rights reserved.
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- Organic Chemistry
- 3405 Organic chemistry
- 3404 Medicinal and biomolecular chemistry
- 0305 Organic Chemistry
- 0304 Medicinal and Biomolecular Chemistry
Citation
Published In
DOI
EISSN
ISSN
Publication Date
Volume
Issue
Start / End Page
Related Subject Headings
- Organic Chemistry
- 3405 Organic chemistry
- 3404 Medicinal and biomolecular chemistry
- 0305 Organic Chemistry
- 0304 Medicinal and Biomolecular Chemistry