Calculations with Enantiomeric Percentages Practice Problems

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 sample enriched with the R enantiomer has a %ee of 76%. What percentage of the sample is racemic? What is the S to R ratio of the enantiomers in the sample?

The specific rotation of the S enantiomer of a proposed cancer treatment drug is −26.9°. A researcher attempted to synthesize an enantiopure form of the said drug but synthesized it with a specific rotation of −22.7°. Determine the S to R ratio of the drug synthesized by the researcher.

An unknown drug has a specific rotation of +82. The commercial synthesis of this drug results in a mixture with an enantiomeric excess of 94%.

a. Determine the absolute configuration (R or S) of this drug.

b. What is the percentage of each of its enantiomers in the commercial product?

A substance has a specific rotation of -40.0. In a polarimeter tube that is 5 cm long, a solution of the compound (0.81 g/100mL) causes an observation of the rotation of -7.52. How much of each enantiomer is in the solution?

A commercial drug has an enantiomeric excess of 86% of R isomer. Determine the percentage of the S isomer.