Sharpless epoxidation of geraniol gave two products,epoxide I (85%)and epoxide II (15%).This mixture of epoxides represents what percent optical purity (or percent enantiomeric excess,% ee)?

Question

Quizplus · Accepted Answer

The Sharpless epoxidation reaction introduces a chiral center at the allylic carbon of geraniol, resulting in two possible stereoisomers: (R)-epoxide and (S)-epoxide. The reaction yields these two stereoisomers in a ratio determined by the enantiomeric excess (ee) of the Sharpless reagent used in the reaction. Since epoxide I is 85% of the product, and assuming that it is either the (R)- or (S)-enantiomer, the ee can be calculated as follows:

ee = ([major enantiomer] - [minor enantiomer]) / ([major enantiomer] + [minor enantiomer]) x 100%
ee = (85 - 15) / (85 + 15) x 100%
ee = 70%

Therefore, the answer is (C) 70%.

Sharpless Epoxidation of Geraniol Gave Two Products,epoxide I (85%)and Epoxide