NEW LARIAT ETHER CARBOXYLIC AND HYDROXAMIC ACIDS - SYNTHESIS AND LANTHANIDE ION COMPLEXATION

Twenty-six new lariat ether carboxylic and hydroxamic acids based upon dibenzo-13-crown-4, dibenzo-14-crown-4, dibenzo-16-crown-5 and dibenz o-19-crown-6 ring systems are synthesized and the solid-state structur e for a dibenzo-19-crown-6 lariat ether hydroxamic acid is determined. The efficiency and selectivity for lanthanide ion extraction into chl oroform by these proton-ionizable lariat ethers is strongly influenced by the crown ether ring size, lipophilic group attachment site and id entity of the acidic function. In general, the lariat ether hydroxamic acids were more efficient and selective lanthanide ion extractants th an the corresponding lariat ether carboxylic acids. The H-1 nmr and ir binding studies indicate that both the macrocyclic polyether unit and the proton-ionizable group are involved in lanthanide ion complexatio n.