What is the specific rotation of pure (S)-carvone if a sample of (R)-carvone of 85% ee has a specific rotation of −52?

Question

Quizplus · Accepted Answer

The specific rotation of (R)-carvone is -52, which means the specific rotation of (S)-carvone must be the same but with the opposite sign. Therefore, the specific rotation of pure (S)-carvone would be +52. Since the enantiomeric excess of (R)-carvone is 85%, we can use the equation [α]obs = %ee × [α]pure to find the observed specific rotation of the mixture, which is -52 = 85% × (+52) + 15% × ??? Solving for ??? gives us +61, which is the specific rotation of (S)-carvone in the mixture. Therefore, the specific rotation of pure (S)-carvone would also be +61.

What Is the Specific Rotation of Pure (S)-Carvone If a Sample