Collect. Czech. Chem. Commun. 1990, 55, 941-950

Potentiometric ion-pair formation titrations of N-alkyl-N-ethylpyrrolidinium cations using plastic membrane electrodes

Karel Vytřasa, Tomáš Čapounb, Emil Halámekb, Jan Součekb and Blanka Štajerováa

a Department of Analytical Chemistry, Institute of Chemical Technology, 532 10 Pardubice
b Department of Chemistry, Military College, 682 03 Vyškov


Cations of the homologous series of N-alkyl-N-ethylpyrrolidinium salts were determined with a good precision by a titration using sodium tetraphenylborate titrant and potentiometric indication with a simple PVC membrane coated-wire electrode. The value of the potentiometric titration break depended on the number of carbon atoms in the alkyl chain. To explain the role of the equilibria involved, the values of both the distribution ratios and the extraction constants as well as the solubility products of N-alkyl-N-ethylpyrrolidinium tetraphenylborates were determined. The value of the titration break could readily be correlated with the logarithmic values of the extraction parameters.