Pipecolic Acid → Pipecolic acid, (-)-

Participants

Reaction Steps

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).

Provenance & Evidence