Process of isolating enantiomer components from enantiomer mixtures by particle-size-controlled crystallization

A process for isolating enantiomer components from a mixture of enantiomers through particle-size-controlled crystallization, comprising the steps of:

• (a) forming a solution of a mixture of enantiomers (R) and (S) in a solvent in the absence of any further additives or agents;
• (b) seeding the solution of step (a) simultaneously or consecutively with seed crystals of enantiomer (R) and with seed crystals of enantiomer (S), wherein the seed crystals of enantiomer (R) differ in size and/or in quantity from the seed crystals of enantiomer (S) to allow separation of the crystals composed of a mixture enriched with enantiomer (R) from the crystals composed of a mixture enriched with enantiomer (S);
• (c) inducing simultaneous crystallization of enantiomer (R) and enantiomer (S);
• and
• (d) isolating crystals composed of a mixture enriched with enantiomer (R) from crystals composed of a mixture enriched with enantiomer (S) through size separation of the crystals,
• wherein the mixture of enantiomers (R) and (S) is a mixture of ((R)-(4-Imino-6-methyl-1,4,5,6-tetrahydro-[1,3,5]triazin-2-yl)-dimethylamine (1) and ((S)-(4-Imino-6-methyl-1,4,5,6-tetrahydro-[1,3,5]triazin-2-yl)-dimethylamine (2),
• wherein the enantiomers are present as a salt selected from the group consisting of the 2,4-dichlorophenyl acetate, the chloroacetate, the hydrochloride, the propionate and the succinate salts.