A solution of pure (R)-2-bromobutane has a specific rotation of -23.1°. If a mixture of stereoisomers of 2-bromobutane shows a specific rotation of −14°, determine the percentage of (R)- and (S)-2-bromobutane in it.

• A. (R)-2-bromobutane = 80.3%
  (S)-2-bromobutane = 19.7%
• B. (R)-2-bromobutane = 20%
  (S)-2-bromobutane = 80%
• C. (R)-2-bromobutane = 60.6%
  (S)-2-bromobutane = 39.4%
• D. (R)-2-bromobutane = 39.4%
  (S)-2-bromobutane = 60.6%

Answer: (A)