Question

How was optical rotation different from other physical properties

4. Describe the physical properties (color and state) of L-(+)-tartaric acid, trans-1,2- diaminocyclohexane, and your diastereomeric salt mixture. How is optical rotation different from other physical properties?

Answer 1

L-(+)tartaric acid

Colour is white crystaline powder or colourless crystaline solid.(2R,3R)-2,3-dihydroxybutanedioic acid.Naturally occurring tartaric acid is chiral, and is a useful raw material in organic chemical synthesis. The naturally occurring form of the acid is dextrotartaric acid or L-(+)-tartaric acid (obsolete name d-tartaric acid). Because it is available naturally, it is slightly cheaper than its enantiomer and the meso isomer. The dextro and levo prefixes are archaic terms. Modern textbooks refer to the natural form as (2R,3R)-tartaric acid (L-(+)-tartaric acid), and its enantiomer as (2S,3S)-tartaric acid (D-(-)-tartaric acid). The meso diastereomer is (2R,3S)-tartaric acid (which is identical with ‘(2S,3R)-tartaric acid’).

1,2-diaminocyclohexane

Colourless to Light yellow liquid. A mixture of cis- and trans-1,2-diaminocyclohexane is produced by the hydrogenation of o-phenylenediamine. It is also side product in hydrogenation of adiponitrile. The racemic trans isomer [1:1 mixture of (1R,2R)-1,2-diaminocyclohexane and (1S,2S)-1,2-diaminocyclohexane] can be separated into the two enantiomers using enantiomerically pure tartaric acid as the resolving agent.