Studies on the syntheses and properties of o-methoxycarbonylbenzyl substituted calix[4]arenes

Two new substituted calix[4]arene derivatives 2 and 3 were synthesized by t he reaction of calix [4]arene with methyl o-bromomethyl-benzoate in the pre sence of potassium carbonate under nitrogen. Their compositions and structu res were confirmed by elemental analysis, IRI H-1 NMR and C-13 NMR. Both th e compounds are in the cone conformation. The percent extraction of the tet rasubstituted 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 compoun d 2 with K+ elucidated that the radius of potassium cation may be matched w ith the inclusion cavity formed by the carbonyl and phenoxy groups. There i s only a little extractivity of disubstituted calix [4]arene derivative 3 f or alkali metal ions.