Conductance and Association of Secondary and Tertiary Alkylammonium Salts in Organic Solvents

Abstract

The conductance and ion-association of short-chain (up to five carbon atoms per chain) tetraalkylammonium salts both in polar and nonpolar organic solvents and their mixtures has been extensively studied [1] and, in many respects the understanding of such systems is satisfactory [2 and references cited therein]. A search of the literature for similar systems but with solutes other than the quaternary salts revealed only fragmentary data [3,4] on short-alkylchain compounds, and it seems that no studies were reported on long-chain (at least eight carbon atoms per chain)alkylammonium salts which are widely used as liquid anion-exchange type extractants [5].Within the framework of a project aimed at investigating the solutionchemistry of high-molecular weight alkylammonium salts of the micellar electrolytes type in organic solvents of low and moderately low dielectric constants, we report here on conductance measurements in some binary systems containing secondary and tertiary alkylammonium halides in nitrobenzene, o-nitrotoluene and o-dichlorobenzene. ExperimentalThe alkylammonium salts, white, crystalline and anhydrous, were prepared, purified and analyzed following the method described previously [6]. Analar BDH grade solvents were purified by treatment with activated alumina until no decrease in conductivity resulted upon further purification (nitrobenzene 2X10-8 , nitrotoluene 6X10-'1 and dichlorobenzene <lXIO-u ohm-1 em-I). Table I lists the physical constants used in calculation of the results. All solutions were made up by weight.The conductances of the solutions were measured in a cell having a constant of 0.01 cm-1 using a Beckman Instruments conductivity bridge Model RC-16 B 2 of a maximum resistance of 2.5 X 10 8 ohm. The dielectric constant of solvents was determined by an instrument which was a modification of that used in the Heterodyne Beat method [9]. The sample arm consisted of a sample cell and a factory