Abstract:
Addition of dimethyl sulphoxide (DMSO), imidazole, methanol, pyrazole, 2-pyridone, and tetra-butylammonium perchlorate, in the concentration range of 0.02 to 0.10 mol dm–3, to 0.50 mol dm–3 dodecylammonium propionate (DAP) in benzene, deuterochloroform or dichloromethane results in large shifts of the NH+3 proton resonances of DAP. Less pronounced shifts occur also for the protons immediately adjacent to the functional head groups of DAP (i.e. CH2NH+3 and CH2CO–2) while protons further removed are unaffected. Plots of the observed shift of the NH+3 of DAP against solubilizate concentration are linear and the shifts decrease in the order pyrazole ≳2-pyridone ≳imidazole > tetrabutylammonium perchlorate > DMSO > methanol in benzene, pyrazole∼2-pyridone∼imidazol > methanol in CDCl3, and pyrazole∼imidazole > methanol in CH2Cl2. The data are interpreted in terms of the interactions among the solubilizate, the solvent, and the surfactant. Solubilization sites as well as specific interactions in the reversed micellar pseudo-phase are discussed.
