Proton magnetic resonance investigations of alkylammonium carboxylate micelles in non-aqueous solvents. Part 4.—Effects of dimethyl sulphoxide, imidazole, methanol, pyrazole, 2-pyridone, and tetrabutylammonium perchlorate on dodecylammonium propionate in benzene, deuterochloroform and dichloromethane

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.