Chemistry - STEREO ISOMERISM Question with Solution | TestHub

Question Explanation: Find the optical purity of a mixture of $\mathrm{d}-$ and $\ell$-tartaric acid.

Concept: Optical Purity and Enantiomeric Excess (ee)

Solution:

Optical purity (enantiomeric excess, ee) represents the percentage excess of one enantiomer over the racemic (50:50) mixture.

Given:

d-tartaric acid = 47%

ℓ-tartaric acid = 53% 1. Enantiomeric Excess (ee):    e = ∣53% − 47%∣ = 6%    

2. Optical Purity (with respect to ℓ-isomer):

Since the ℓ-isomer is in excess, the optical purity equals the ℓ-isomer excess: Optical purity = 6%

Thus, the mixture contains 6% excess of the ℓ-tartaric acid enantiomer .

Final Answer:   6