Question

2. what is the ratio of enantiomers in a mixture with an enantiomeric excess of 50%?

1. If (R)-2-bromobutane has a specific rotation of -23°, what is the value of [a], for dextrarotatory 2- bromobutane at the same temperature? +23 2. What is the ratio of enantiomers in a mixture with an enantiomeric excess of 50%? 3. a) Draw the structure of (2S,3S)-2,3-difluorobutane in an extended zig-zag line drawing using wedged and dashed bonds where appropriate.

Answer 1

Given that the enantiomeric excess of the mixture is 50% i.e one of the isomer is present in 50% excess when compared to the isomer. Remaining 50% of the mixture contains 25% one enantiomer and 25% of the opposite enantiomer.

Now, finally in the reaction mixture contains 75% of the enantiomer and 25% of the opposite enantiomer.

The ratio of the enantiomers in a mixture with an enantiomeric excess of 50% is 75: 25 = 3:1