Die Hammett'schen σ-Werte der Gruppen NH2 und NH3+. Zwitterionen-Bildungsgleichgewichte in Lösungen aromatischer Aminosäuren
✍ Scribed by A. V. Willi; Walter Meier
- Book ID
- 102249923
- Publisher
- John Wiley and Sons
- Year
- 1956
- Tongue
- German
- Weight
- 326 KB
- Volume
- 39
- Category
- Article
- ISSN
- 0018-019X
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✦ Synopsis
Abstract
Ionisation constants at 20° and the ionic strength μ = 0,1 were determined for some substituted benzoic acids, some substituted anilines, and for m‐ and p‐phenylendiamines. ϱ values for the benzoic acids and anilines series are calculated. σ values for NH~2~ and NH~3~^+^ are derived from the data for the phenylendiamines, and they are discussed in comparison with values obtained from other reactions.
By application of Hammett's rule, partial ionisation constants for zwitterion and uncharged amino acid forms of aromatic amino acids are calculated. These data combined with experimental pK values (reported in earlier papers) lead to information on the constants for the tautomeric equilibria : zwitterions ⇌ uncharged amino acid. This method is applied for m‐ and p‐aminobenzoic acids and for p‐amino‐salicylic acid.