Extraktion von alkali- und erdalkalimetallionen mit (sym-dibenzo-14-krone-4-oxy)- und (sym-dibenzo-16-krone-5-oxy)-carbonsäuren

Abstract (Extraction of alkali on alkaline earth metal ions with (sym-dibenzo-14-crown-4-oxy)- and (sym-dibenzo-16-crown-5-oxy)-carboxylic acids.) The extraction of lithium, sodium, potassium, calcium and some other metal ions with dibenzo-4-crown-4-oxy- and dibenzo-16-crown-5-oxycarboxylic acids containing the groups -CH 2 COOH, -(CH 2 ) 2 COOH, -(CH 2 ) 3 COOH, -CH(C 2 H 5 )COOH and -CH(C 4 H 9 )COOH was studied. The extraction increases as a function of the lipophilic character of the carboxylic acid group. Calcium, barium and strontium ions are better extracted than Li + , Na + and K + ; there are only small differences among the alkaline earth metal ions. Evaluated from the extraction data, the composition of the extracted species was 1:1 (metal/ligand) for Li + , and 1:2 for CaCa 2+ ; Na + and K + favour the formation of 1:2 complexes with dibenzo-14-crown-4-derivatives bbut 1:1 complexes with dibenzo-16-crown-5-oxy-carboxylic acids. The dependence of the distribution ratio on pH does not provide unequivocal evidence for the composition of the extracted compounds.