Acyclic polyether dicarboxylic acids having butyl and tetradecyl side alkyl chains at the a-position of the carboxylic acid sidearm unit were prepared by the reaction of bisphenol and 2-bromoalkanoic acid in the presence of sodium hydride with quantitative yields. Complexation studies and solvent extraction on complexes of these ethers with alkaline earth metal ions indicate that 1,2-bis((2-2＇-carboxybutyloxy)-phenoxy)ethane (2) shows an excellent selectivity for the calcium ion.