Enantiomeric enrichment of partially resolved N-methyl-amphetamine

The enantiomeric enrichment of N-methyl-amphetamine (MA) was tried by eight different preparative separation methods. The enrichment process was also studied by thermoanalitical methods (DSC,TG). There is no enantiomeric enrichment during fractional distillation and selective extraction of the liquid base. The enantiomeric mixture of MA·HCl can be enriched by crystallization or by sublimation. The most effective enrichment can be achieved by fractional crystallization or distillation of the reaction mixture after partial salt formation with hydrochloric acid. The separation is less effective in case of fractional steam distillation and selective extraction when the enantiomer and the racemate are distributed between two liquid phases. This supports the general experience that having a solid phase in the system makes enantiomer separation more efficient.