Equilibrium constants and protonation site for N-methylbenzenesulfonamides

• José A. Moreira,
• Ana M. Rosa da Costa,
• Luis García-Río and
• Márcia Pessêgo

Beilstein J. Org. Chem. 2011, 7, 1732–1738, doi:10.3762/bjoc.7.203

• Biológica y Materiales Moleculares, Departamento de Química Física, Facultad de Química, Universidad de Santiago, 15782, Santiago de Compostela, Spain 10.3762/bjoc.7.203 Abstract The protonation equilibria of four substituted N-methylbenzenesulfonamides, X-MBS: X = 4-MeO (3a), 4-Me (3b), 4-Cl (3c) and 4

• parameter than with σ, which indicates that the initial protonation site is the oxygen atom of the sulfonyl group. Keywords: linear free-energy relationships; N-methylbenzenesulfonamides; protonation equilibrium; Introduction Having a knowledge of the protonation equilibrium constants for N

• structures, the latter having a greater relevance for the sulfonamides with electron-donor groups (Scheme 3). Conclusion The protonation equilibrium constants (pKBH+) for the para-substituted N-methylbenzenesulfonamides 3a–d in aqueous sulfuric acid were obtained from spectrophotometric measurements