Cooling Enantiomorphism

Two mols, for example, 270 grams, of racemic a-methylphenethylamine base are reacted with one mol (150 grams) of d-tartaric acid, thereby forming dl-a-methylphenethylamine d-tartrate, a neutral salt. The neutral salt thus obtained is fully dissolved by the addition of sufficient, say about 1 liter, of absolute ethanol, and heating to about the boiling point. The solution is then allowed to cool to room temperature with occasional stirring to effect crystallization. The crystals are filtered off and will be found to contain a preponderance of the levo enantiomorph. 

G values are greater for heating up than for cooling down in a temperature range from 50 to 80°C. Such a hysteresis behavior was not observed for the enantiomorphic form, and... 

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