[C:1](OC(=O)C)(=O)C.[C:8]([O:11][CH2:12][C@H:13]([O:15][CH3:16])C)(=[O:10])[CH3:9].C(=O)([O-])[O-].[Na+].[Na+].C(=O)=O>O.[Cl-].[Zn+2].[Cl-]>[C:8]([O:11][C@@H:12]([CH3:1])[CH2:13][O:15][CH3:16])(=[O:10])[CH3:9]To a 25-ml flask was added 4.0 g (0.044 mole) of the (S)-PM-2/(R)-PM-1 mixture with 0.02 g anhydrous zinc chloride. A reflux condenser with drying tube was attached and 4.7 g (0.046 mole) acetic anhydride was added by lifting the drying tube momentarily. The mixture was refluxed at about 118° C. for 2 hours and then allowed to cool. GC-analysis of a 1% solution in water showed a single peak for PMA-2 with retention time matching the first peak observed for commercial PMA-2 enantiomers. These results indicated that the first PMA-2 peak is the (S) enantiomer. A single peak was also observed for the PMA-1 enantiomer. This peak also matched the first peak for PMA-1, present in ˜3% in the commercial mixture, indicating that it was (R)-2-methoxy-1-propanol acetate. These results indicate that the (R) and (S) PMA-1 enantiomers exhibit opposite elution order from that observed for the corresponding PMA-2 enantiomers. The mixture was neutralized by adding 2.44 g (0.024 mole) anhydrous sodium carbonate and stirring for approximately 1 hour with CO2 evolution. A short path distillation head was attached and the reaction product was distilled using a heat gun as heat source. About 5.0 g material boiling in the 95-137° C. range was collected. GC analysis showed sample purity to be about 95% (S-PMA-2 92.6% and R-PMA-1 2.7%).
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