Enantiomeric resolution of (+/-)-5-ethyl-5-methylhydantoin by means of preferential nucleation

Enantiomeric resolution of the title compound is performed by means of pref erential nucleation. The antagonism between the absolute configuration of t he dissolved additive and the absolute configuration of the major part of t he solute resulting from the process is confirmed (rule of reversal). Exper imental data suggest that the stereospecific induction of the nucleation (p referential primary nucleation) results from the chiral additive whereas th e enantiomeric enrichment results from a combination of high secondary nucl eation rate and crystal growth, both driven by stirring effect.