Conductivities in Thionyl Chloride

Abstract

Conductivity measurements in thionyl chloride are reported for dilute solutions of AICIs, LiAICI4, and the tetrapropylammonium (Pr4N) salts Pr4NCI, Pr4NCIO4, Pr4NAICI4. The data for electrolyte solutions having concentrations in the range of ,,,0.01 to 1 X 10 -5 mole dm -~ were fitted empirically to an equation of the Fuoss-Hsia type. In all cases except for AICIs ion pair formation was found to he extensive. AICIs solutions in thionyl chloride appear to be complex possibly owing to the formation of complex species such as A12C18 and AIsCIT-. The effect of ionic strength on the solubility of LiCl is discussed.In addition to the interesting general solvent properties of thionyl chloride (1), this solvent has received considerable attention as a cathode depolarizer in primary lithium batteries (2, 3). A number of important physico-chemical properties of electrolytic solutions have been reported (1, 4) including the conductivities of LiA1C14 solutions (4). In the present paper, the conductivities of dilute solutions (between 0.01 and 1 • 10 -5 mole dm -8) of various salts including L!A1C14 are reported and analyzed in accordance with an ion pairing model. The dielectric constants and densities of the pure solvent over a small temperature range are also reported. ExperimentalChemicals.--Purified LiA1C14 was supplied by W. K.Behl of this laboratory and was purified as described previously (3). Fluka purris A1C13 was sublimed in vacuum and transferred to a dry box while under vacuum. Tetrapropylammonium perchlorate (Pr4NC104) was recrystallized from distilled water, and Pr4NC1 was precipitated from an acetone/ether mixture: both salts were dried in a vacuum at 60~ and stored in the dry box. AR grade LiC1 was dried at 110~ and stored in the dry box. Tetrapropylammonium tetrachloroaluminate, Pr4NA1C14, was prepared in the dry box by mixing stoichiometric quantities of A1CI~ and Pr4NC1 followed by addition of the solvent. SOC12 (MC/B best grade) was refluxed with P205 at room temperature for 24-48 hr before distillation: the middle 2/3 of the colorless distillate was retained for use. A Vacuum Atmospheres Corporation dry box with an argon atmosphere was used in this work.Dielectric constant measurements.--The static dielectric constants at 15 ~ 25 ~ and 35~ were measured by the comparison method (5), The cell, which utilized Type 304 stainless steel, consisted of concentric steel electrodes threaded onto a Teflon base which also formed part of a water jacket. The cell capacitances were measured at 1 MHz by a substitution method with a General Radio 1606-B bridge and 722-D and 1422-ME precision capacitors. The cell constants were deter-* Electrochemical Society Active Member. mined from measurements with air, benzene, and tetrahydrofuran. The cell was filled with SOC12 in the dry box, sealed with a Teflon stopper, and removed to the laboratory for capacitance measurements at 15 ~ 25 ~ and 35 ~ -4-0.1~ Conductivity measurements.--These measurementswere carried out at 25 ~ __ 0.03~ (uncalibrated thermometer) at 1 kHz using a...

Conductance Studies in Thionyl Chloride: II

“…is essentially constant for KCCD values > 1 • 10 -5 mol dm -8. For all the solutes studied in the present and previous work (1), values of K ~D were always found to be greater than 2 • 10-5 tool dm -3, and it is therefore reasonable to take a lower limit of K~D : 1 X 10 -5 tool dm -3 for NaC1 and KC1. On this basis it is estimated that Csatd.…”

“…0.03~ An Altex model RC-18A conductivity bridge was used for the measurements: The stated accuracy of this bridge is • 0.05%. All solutions were prepared by volume in the dry box at 22~176 and concentration corrections to 25 ~ were made using the temperature coefficient of the density for the pure solvent (1).…”

“…Previous studies (1) on the conductivities of tetrapropylammonium salts, LiAIC14, and LiCI in SOC12 at 25~ have been extended to include tetramethyl-, tetraethyl-, tetrabutyl-ammonium salts (Me4N+, Et4N +, and n-Bu4N +, respectively), and sal~s of tetraphenylarsonium (Ph4As +) and tetraphenylboride (BPh4-). The conductivity data are analyzed in terms of an ion pairing model according to MX --M + -{-X-KcoD [1] and, as expected, all salts are highly associated. From the measured electrolytic conductivities of saturated NaC1 and KC1 solutions, the thermodynamic solubility product constants are estimated for the following reaction MCI(s) : M + (sln) -~ C1-(sln) K~o [2]…”

Titrations in nonaqueous solvents

“…The effect of solvent composition on the conductivity and ion association of tetraalkylammonium and tetraphenylphosphonium salts was studied in acetone, dimethyl sulfoxide, water, and their binary mixtures (427). An ion-pair model was used to analyze data collected in thionyl chloride on lithium chloride and lithium tetrachloroaluminate, and for several tetraalkylammonium salts (423). Both conductance and visible spectroscopy were used to establish the existence in acetonitrile (AN) of species of the type [M(AN)6]2+-2BF4~, where M is cobalt, nickel, manganese, copper, or zinc (302).…”