5. Chirality

The [α] of pure S-epinephrine is +50°. Calculate the ee of a solution with an observed value of -40°. Calculate percent of each enantiomer. Then sketch the approximate mixture in our sample polarimeter tube.

A sample of (S)-(+)-lactic acid was found to have an enantiomeric excess of 72%. How much R isomer is present in the sample?

A compound has a specific rotation of -39.0. A solution of the compound (0.187 g/100 mL) has an observed rotation of -6.52° when placed in a polarimeter tube 10 cm long. What is the percent of each enantiomer in the solution?

Naproxen, a nonsteroidal anti-inflammatory drug that is the active ingredient in Aleve (p. 115), has a specific rotation of +66. One commercial preparation results in a mixture with a 97% enantiomeric excess.

a. Does naproxen have the R or the S configuration?

b. What percent of each enantiomer is obtained from the commercial preparation?