Question

3. Write short paragraph describing about how you could convert your salt (final product) back to the free diamine. Describe the experimental details that would be needed to generate your optically pure diamine.

trabs 1-2- diaminocyclohexane

Answer 1

The (S, S) diamine-L-Tartarate salt is soluble in water and diastereomer of that (R, R) salt is insoluble in water. Once the salts are prepared with L-Tartaric acid in water. The residue is filtered off using filter paper. This solid residue is of (R, R) diamine isomer. The solid is mixed with ice-cold aqueous NaOH solution to make pH > 9. This leads to the formation of the soluble sodium salt of L-tartaric acid leaving behind the desired (R, R) diamine insoluble in water. But this is a low melting solid (MP= 41-45^oC). Hence, make sure to use an ice-cold solution. the solid is filtered under the cold condition and washed with ice-cold water.