Synthesis and complex-forming properties of crown ethers incorporating glucuronic acid moieties

Crown ethers 1 and 4 of the 18-crown-6 type containing two glucose units have been oxidised by KMnO4 into mono- and dicarboxylic acid derivatives (5 and 11), and derivatives with different lipophilicities of the above crown ethers, namely the acetyl, benzyl and butyl derivatives (8-10, 13, 14) and methyl esters (6 and 12) have been synthesized. The association constants (K-a) with Li, Na, K and NH4 cations measured in CHCl3 indicate that complexing ability increases on introduction of carboxy groups, and selectivity changes in favour of the Na cation. These compounds were able to transport alkyl-ammonium salts through a CHCl3 liquid membrane, displaying, however, no chiral recognition ability.