The Use of Deuterium Magnetic Resonance in the Determination of the Structure and Location of the Anilinium Ion in an Aqueous Anisotropic Surfactant Solution

Abstract

Anisotropic soap solutions containing the anilinium ion have been studied by n.m.r. techniques. The partially averaged proton–proton dipole couplings were used to obtain the relative positions of the hydrogen nuclei of the phenyl ring. Deuterium quadrupole splittings from the deuterium enriched ion provided information concerning the quadrupole coupling constant, Q_D, the asymmetry parameter, η, and the angles that the C—D bonds make with the coordinate systems axes. Quadrupole splittings from the deuterium enriched decylsulfate simultaneously with those from the anilinium ion established that the C₂ axis of the ion on an average lies parallel to the decylsulfate chain axis and is ordered to a similar extent. It is concluded that the aromatic ring is incorporated into the superstructure of the soap solution and that the —NH₃⁺ group protrudes into the electrical double layer where it interacts with the oppositely charged decylsulfate and with water.