Abstract: Two new substituted calix[4]arene derivatives 2 and 3 were synthesized by the reaction of calix[4]arene with methyl o-bromomethyl-benzoate in the presence of potassium carbonate under nitrogen. Their compositions and structures were confirmed by elemental analysis, IR, ¹H NMRand ¹³C NMR. Both the compounds are in the cone conformation. The percent extraction of the tetrasubstituted calix[4]arene derivative 2 for Li⁺, Na⁺, K⁺ and Cs⁺ are 6.8, 19.4, 69.8 and 7.1, respectively, indicating that derivative 2 extracts K⁺ better than Li⁺, Na⁺ and Cs⁺. The higher selective complexation of compound 2 with K⁺ elucidated that the radius of potassium cation may be matched with the inclusion cavity formed by the carbonyl and phenoxy groups. There is only a little extractivity of disubstituted calix[4]arene derivative 3 for alkali metal ions.

Key words: Calix[4]arene, Potassium ion, Extraction