Selective chromogenic reagents based upon phenolic cryptands
Abstract
Chloroform solutions of the chromoionophore 4c, which has been synthesised by a simple procedure from diaza-15-crown-5 2a, extract lithium cations from aqueous solutions in the pH range 7–8 with very high selectivity as compared with the extraction of sodium, potassium, magnesium and calcium; the related reagent 5 shows moderate selectivity for sodium.