Abstract
The position of the -OH proton resonance of methanesulfonic acid has been measured at various dilution in several solvents containing -OH group, such as water, methanol and ethyleneglycol. In all solvents studied, a single resonance line was observed. The proton resonance of the -OH group moves first to low field and to high field with increasing dilution. From the dilution curves it was found that in water, methanol and ethyleneglycol this movement of the -OH signal to high field commences at the following concentrations (more ratio of the sulfonic acid to the solvents); 3:1, 2:1 and 4:1. This suggests that sulfonic acid forms 3:1, 2:1 and 4:1 complexes with water, methanol and ethyleneglycol where hydrogen bonds play major roles.
The chemical shifts for the ionizable proton in aqueous, methanol and ethyleneglycol solutions of methanesulfonic acid and benzenesulfonic acid have been measured at 34°C. In all cases studied, a single resonance line was observed and the proton chemical schifts dependedd upon the concentration of the acids. From the observed proton chemical shifts relative to the pure solvents, the degrees of ionization of the sulfonic acids have been calculated. The ionization constants estimated in the solvents were in the following order; water ≥ ethyleneglycol > methanol.
