Synthesis of a Lithium Specific Chromogenic Crown Ether

Abstract
Recent experiments have shown that monobasic chromophoric crown ethers have very selective extraction behavior making them useful as analytical organic reagents.(1–6) The chromogenic crown ethers are synthesized by reacting a chromophore like picryl chloride to an aminobenzo crown ether. One such compound 2″4″-dinitro-6-trifluoromethylphenyl-4′-aminobenzo-15-crown-5 (1) exhibits linear response to K+ from 700-5ppm in the presence of 3000ppm Na+.