Extraction of potassium with trifluoromethyl-substituted chromogenic crown ethers

Abstract

Two new chromogenic crown ethers with trifluoromethyl substituents have been synthesised and evaluated as reagents for the extraction and spectrophotometric determination of potassium in the presence of sodium. These crown ethers, 4′-(2″, 6″-dinitro-4″-trifluoromethylphenyl)aminobenzo-15-crown-5 (4TF) and 4′-(2″, 4″-dinitro-6″-trifluoromethylphenyl)aminobenzo-15-crown-5 (6TF), exhibited large differences in the values of λ_max. and molar absorptivity for the complexed and uncomplexed species and also in their extraction efficiencies. 6TF showed the best extraction efficiency and was capable of extracting 5–700 p.p.m. of potassium ions in the presence of 3000 p.p.m. of sodium ions.