Hydrochloric Acid → Ethyl 4-(4-aminobutyl)piperazine-1-carboxylate

A solution of 200 g of ethyl 4-(3-cyanopropyl)-piperazine-1-carboxylate and 20 g of cobaltous chloride hexahydrate in 2 liters of methanol was cooled in ice and 125 g of sodium borohydride were added in portions with stirring at a temperature of less than 10° C. When the addition was complete, the mixture was stirred at 20° C. for 16 hours and then ~300 ml of concentrated HCl were added thereto until the black suspension turned blue. The solvent was removed under vacuum and the residue was dissolved in 2 liters of water and filtered. The filtrate was adjusted to a pH of 8 with potassium carbonate and was washed with 200 ml of carbon tetrachloride to remove non-polar impurities. The pH of the solution was increased to 9-10 by the addition of more potassium carbonate and then was saturated with sodium chloride. The mixture was extracted 6 times with 250 ml of chloroform and the combined extracts were dried over MgSO4 and evaporated to dryness to obtain 30 g of ethyl 4-(4-aminobutyl)-piperazine-1-carboxylate in the form of a light brown oil which was distilled under reduced pressure to give a pure fraction with a boiling point of 135°-140° C. at 0.3 mm Hg.

1. additionWhen the addition
2. stirringthe mixture was stirred at 20° C. for 16 hours
3. customThe solvent was removed under vacuum
4. dissolutionthe residue was dissolved in 2 liters of water
5. filtrationfiltered
6. washwas washed with 200 ml of carbon tetrachloride
7. customto remove non-polar impurities
8. temperatureThe pH of the solution was increased to 9-10 by the addition of more potassium carbonate
9. extractionThe mixture was extracted 6 times with 250 ml of chloroform
10. dry with materialthe combined extracts were dried over MgSO4
11. customevaporated to dryness

ORD record

ord-c9d0e93a3f2945c9a44821f1cd7a9541

Source dataset

uspto-grants-1983_06

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04390697