[dirac23]

Hi all. I'm stuck on a question for my organic chemistry class. We're asked to outling a procedure for resolving a racemic mixture of tartaric acid using chiral 1-phenylethanamne to isolate the (-)-tartaric acid. I'm really not sure where to go with this at all. I was thinking along the lines of a diluton and proceeding wth polarimetery, but i'm not quite sure. Any help would be appreciated.

[skbuncks]

Hi all. I'm stuck on a question for my organic chemistry class. We're asked to outling a procedure for resolving a racemic mixture of tartaric acid using chiral 1-phenylethanamne to isolate the (-)-tartaric acid. I'm really not sure where to go with this at all. I was thinking along the lines of a diluton and proceeding wth polarimetery, but i'm not quite sure. Any help would be appreciated.

Errr, no. Try thinking more along the lines of what physical properties diastereoisomers possess that enantiomers do not.

skb

[AWK]

Usually diastereomeric salts are separated by crystallization.

[OC pro]

Stirring of an 0,5-1 (amine):1 (racemate of acid)-mixture in an appropiate solvent (THF, EtOH) at room temperature. One enantiomer of the tartaric acid will make a salt with phenylethylamine and thus will crystallize out. The crystals can be filtered and washed and even recrystallized to get better enantiomeric purity. Liberation of the free acid can be done by dissolving the crystals in 1N HCl and extraction with ethyl acetate. Phenylethylamine can then be recovered from the aqueous phase by basification and extraction.

[sjb]

Stirring of an 0,5-1 (amine):1 (racemate of acid)-mixture in an appropiate solvent (THF, EtOH) at room temperature. One enantiomer of the tartaric acid will make a salt with phenylethylamine and thus will crystallize out. The crystals can be filtered and washed and even recrystallized to get better enantiomeric purity. Liberation of the free acid can be done by dissolving the crystals in 1N HCl and extraction with ethyl acetate. Phenylethylamine can then be recovered from the aqueous phase by basification and extraction.

At least, that's the theory (yes, I know there's an orgsynth prep on these lines).