Synonyms: Pentacyclo[19.3.1.13,7.19,13.115,19]octacosane,acetic acid deriv.; 4-tert-Butyl calix[4]arene-O,O',O'',O'''-tetraacetic acidtetraethyl ester; 4-tert-Butylcalix[4]arenetetra-O-acetic acid tetraethylester;5,11,17,23-Tetra-tert-butyl-25,26,27,28-tetrakis(2-ethoxy-2-oxoethoxy)calix[4]arene;Sodium ionophore X; tert-Butyl calix[4]arenetetraacetic acid tetraethyl ester