Process for preparing (S) and (R)-2-[4-(4-chlorobenzhydryl)piperazin-1-yl]-ethoxyacetamide

1. Chromatographic process for preparing (S)-2-[4-(4-chlorobenzhydryl)piperazin-1-yl]-ethoxyacetamide and (R)-2-[4-(4-chlorobenzhydryl)piperazin-1-yl]-ethoxyacetamide, by enantiomeric resolution of 2-[4-(4-chlorobenzhydryl)piperazin-1-yl]-ethoxyacetamide, which process comprises using a system comprising series of fixed-bed columns connected in series, wherein the charge (solution of the compounds to be separated) and the eluent are injected continuously into the system while the separated compounds are removed continuously in the extract (compound most strongly retained) and the raffinate (compound least strongly retained), wherein the system comprises at least six columns filled with chiral stationary phase.

2. Process according to claim 1 , wherein the chiral stationary phase is chosen from phases based on silica gel supporting polymeric compounds.

3. Process according to claim 1 , wherein the chiral stationary phase is a phase based on silica gel supporting an ester or a carbamate of cellulose or of amylose.

4. Process according to claim 1 , wherein the system uses at least one column packed with an optical resolution packing material, said packing material consisting of silica gel supporting amylose tris(3,5-dimethylphenylcarbamate) or a chemically modified form thereof.

5. Process according to claim 4 , wherein the average particle diameter of the packing material is 1 to 300 μm.

6. Process according to claim 5 wherein the particles of the packing material are porous.

7. Process according to claim 6 , wherein the pore diameter of the particles is 10 Å–5000 Å.

8. Process according to claim 4 , wherein the amylose tris(3,5-dimethylphenylcarbamate) or chemically modified form thereof is 1 to 99% weight percent of the silica gel support.

9. Process according to claim 1 , wherein it is performed at a temperature of 5–50° C.

10. Process according to claim 1 , wherein the system comprises eight columns.

11. Process according to claim 1 , wherein the system uses an eluent an alcohol or mixture of alcohol and of alkane in a proportion (by volume) of between 50/50 and 100/0.

12. Process according to claim 1 , wherein the system uses an eluent selected from methanol, or a mixture of n-heptane and n-propanol.

13. Process according to claim 2 , wherein the polymeric compounds are selected from polysaccharide derivatives, polyacrylic derivatives and polyamide derivatives.