Question

What is the ee for each of the following mixtures of enantiomers A and B?

a. 95% A and 5% B

b. 85% A and 15% B

Short answer

a. The ee is 90%.

b. The ee is 70%.

Step-by-step solution

Enantiomeric excess (ee)

The enantiomeric excess determines the excess amount of any one of the enantiomers (either R or S). It is also termed an optically pure compound.

Formula to calculate the ee

The formula to calculate the ee is as follows:

$\text{ee=\%ofoneenantiomer-\%ofotherenantiomer}$.

Explanation

a. The ee is calculated from the A and B as:

$$\begin{gathered} \text{ee=95\%-5\%} \\ =5\% \end{gathered}$$

Therefore, the ee for enantiomers is 90%.

b. The ee is calculated from the A and B as:

$$\begin{gathered} \text{ee=85\%-15\%} \\ =70\% \end{gathered}$$

Therefore, the ee for enantiomers is 70%.