Supercritical fluid extraction: a novel method for the resolution of tetramisole

A new resolution method, based on the selective distribution of enantiomers between a chiral solid and an achiral supercritical fluid phase, is report ed. The chiral solid phase is formed from the optically active dicarboxylic acid derivative, (2R,3R)-O,O'-dibenzoyltartaric acid, and the racemic base (tetramisole). A new method is also described for the enrichment of enanti omeric mixtures which have an enantiomeric ratio other than 1:1. This is ba sed on the partial salt formation of the enantiomeric mixture with an achir al substance, which is then followed by supercritical fluid extraction of t he free enantiomer. The extract has an enantiomeric composition which is di fferent from the starting mixture. The method is applied to an enantiomeric mixture of tetramisole with hydrochloric acid. (C) 1999 Elsevier Science L td. All rights reserved.