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.

Thalidomide is a drug used to treat cancer, several skin disorders, and particular complications caused by human immunodeficiency virus (HIV). The (–)-isomer is the biologically active form of thalidomide. A sample of a mixture of thalidomide has a specific rotation of [α]_D = –45.1°. Using the specific rotation of the pure enantiomer below, determine the ratio of (+)- to (–)-thalidomide in the sample.

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

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?