A MEMBRANE-STABILIZED PREFERENTIAL CRYSTALLIZATION PROCESS

RACEMIC MIXTURES OF CHIRAL COMPOUNDS THAT CRYSTALLIZE AS CONGLOMERATE MIXTURES MAY BE OPTICALLY RESOLVED USING THE TECHNIQUE OF DIRECT PREFERENTIAL CRYSTALLIZATION. THE METHOD IS BASED ON THE SELECTIVE DEPOSITION OF ENANTIOMERS FROM SUPERSATURATED SOLUTION ONTO OPTICALLY PURE SEED CRYSTALS PROVIDED FOR THIS PURPOSE. THE TECHNIQUE HAS INHERENT ADVANTAGES IN ITS AVOIDANCE OF THE CHIRAL AUXILIARIES AND ADDITIONAL PROCESS CHEMISTRY THAT ARE CHARACTERISTIC OF OTHER METHODS FOR PRODUCING OPTICALLY PUREDRUGS. WHILE PREFERENTIAL CRYSTALLIZATION HAS BEEN APPLIED SUCCESSFULLY TO PRODUCE SEVERAL IMPORTANT CHIRAL COMPOUNDS, IT WOULD UNDOUBTEDLY BE MORE WIDELY USED WERE IT NOT FOR THEFACT THAT SELECTIVE CRYSTALLIZATION CAN BE A DIFFICULT PROCESS TO CONTROL ON THE LARGE SCALE. IT'S PROPOSED TO EXAMINE THE FEASIBILITY AND POTENTIAL BENEFITS OF MEMBRANE-STABILIZED PREFERENTIAL CRYSTALLIZATIONFOR STEREOISOMER SEPARATIONS. IN THIS NOVEL PROCESS, SELECTIVE MEMBRANES ARE USED TO CONFINE INDIVIDUAL ENANTIOMERS AND SEED CRYSTALS IN SUCH A WAY AS TO ENHANCE THE STABILITY OF CRYSTALLIZATION AND THEREBY TO IMPROVE PROCESS RELIABILITY AND EFFICIENCY.