Separation of chlorothalidone enantiomers by chiral extraction with lipophilic L-tartaric esters

Distribution behavior of chlorothalidone enantiomers was examined in aqueous-1 2-diochloroethane of a two-phase system containing one of L-tartaric esters. The influence of pH. length of alkyl chain of L-tartraic esters, concentrations of L-tartaric esters and phosphate salt on partition coefficients and separation factors was investigated. The experimental results show that L-tartaric esters studied all form more stable diastereomeric complexes with chlorothalidone I (+)-enantiomer than with II (-)-enantiomer. With addition of length of alkyl chain of L-tartaric esters, partition coefficients (K) and separation factors (alpha) increase. With increase of pH, K increases, but alpha decreases. The concentrations of L-tartaric esters and phosphate salt also have a big influence on K and alpha.