Assessing ion-exchange properties and purity of lipophilic electrolytes by potentiometry and spectrophotometry

D S Silvester; E Grygolowicz-Pawlak; Eric Bakker

doi:10.1016/j.elecom.2009.10.048

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Assessing ion-exchange properties and purity of lipophilic electrolytes by potentiometry and spectrophotometry

Journal article

Peer reviewed

Assessing ion-exchange properties and purity of lipophilic electrolytes by potentiometry and spectrophotometry

D S Silvester, E Grygolowicz-Pawlak and Eric Bakker

Electrochemistry Communications, Vol.12(1), pp.110-113

2010

DOI: https://doi.org/10.1016/j.elecom.2009.10.048

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Abstract

ETH 500

potentiometry

ionic liquid purity

inert lipophilic electrolyte purity

nile blue

spectrophotometry

Many ionic salts synthesized using metathesis are often found to contain significant amounts of impurities, despite careful control of the weighing of starting materials. In this work, a potentiometric method is devised to monitor ion-exchange properties (or ‘purity’) of an organic solvent containing a lipophilic electrolyte. Its permselective behaviour is monitored by treating the solvent as a liquid membrane and contacting it with two aqueous solutions with different electrolyte activities. This electrolyte mismatch results in a drastic potential change when excess lipophilic cation-exchanger is titrated with anion-exchanger, altering the membrane from being cation to anion responsive. Here, the cation-exchanger potassium tetrakis(4-chlorophenyl)borate (KTpClPB) dissolved in nitrobenzene was titrated with tetradodecylammonium chloride (TDDACl), in contact with Ag/AgCl electrodes placed in aqueous 1 M and 10−2 M KCl, respectively. The predicted potential change of −214 mV was observed at the equivalence point, forming the inert lipophilic electrolyte ETH 500, in a very small concentration range of added anion-exchanger (0.8% for ±10 mV), suggesting good precision. The approach was confirmed by monitoring absorbance and fluorescence intensity changes of the chromoionophore Nile Blue. This method may be applied for the synthesis of a range of highly lipophilic salts for which established metathesis protocols are not suitable.

Details

Title: Assessing ion-exchange properties and purity of lipophilic electrolytes by potentiometry and spectrophotometry
Authors: D S Silvester (Author) - Curtin University of Technology
E Grygolowicz-Pawlak (Author) - University of Geneva, Switzerland
Eric Bakker (Author) - Curtin University of Technology
Publication details: Electrochemistry Communications, Vol.12(1), pp.110-113
Publisher: Elsevier Inc.
Date published: 2010
DOI: 10.1016/j.elecom.2009.10.048
ISSN: 1388-2481
Organisation Unit: University of the Sunshine Coast, Queensland
Language: English
Record Identifier: 99450034602621
Output Type: Journal article

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