反应详情

483 g (=3.75M) of enriched (-)-pipecolic acid are suspended in 3 liters of hot methanol. 565 g of D-(-)-tartaric acid are rapidly scattered in and an attempt made as quickly as possible to obtain a solution. Crystallization commences before a complete dissolution can be achieved. The mixture is cooled, filtered and well washed with methanol. The filtrate is concentrated and recrystallized. The obtained crystals are dissolved hot in ca 800 ml of water and 400 ml at acetone and treated with active charcoal. The clear almost colorless filtrate is diluted with ca 2 liters of acetone. The resulting crystals are filtered of and well washed with acetone/H2O 4:1 followed by 100% acetone. The filtrate is concentrated and diluted with acetone to obtain a second fraction. Both fractions are dried. [α]D20 =20.3° for the first fraction and -20.7° for the second fraction, (c=2, H2O) total weight 706 g. Separation is effected with 3 liters of Amberlite 7R 120 in the H+ form. After working the tartrate salt with 10% ammonia, the L-(-)-pipecolic acid is obtained by elution and concentration by evaporation and then once recrystalized out of a minimum of H2O and a maximum of alcohol, [α]D20 -27.5 (C=2, H2O).

1. customto obtain a solution
2. customCrystallization commences
3. dissolutionbefore a complete dissolution
4. temperatureThe mixture is cooled
5. filtrationfiltered
6. washwell washed with methanol
7. concentrationThe filtrate is concentrated
8. customrecrystallized
9. dissolutionThe obtained crystals are dissolved hot in ca 800 ml of water
10. addition400 ml at acetone and treated with active charcoal
11. additionThe clear almost colorless filtrate is diluted with ca 2 liters of acetone
12. filtrationThe resulting crystals are filtered of and
13. washwell washed with acetone/H2O 4:1
14. concentrationThe filtrate is concentrated
15. additiondiluted with acetone
16. customto obtain a second fraction
17. customBoth fractions are dried
18. custom[α]D20 =20.3°
19. customfor the first fraction and -20.7°
20. customSeparation