Question

The specific rotation of a pure enantiomer is `+16^(@)` its observed rotation if it is isolated from a reaction with 25% racemisation and 75% retention is,
A. `-12^(@)`
B. `+12^(@)`
C. `+16^(@)`
D. `-16^(@)`

Answer 1

Correct Answer - B
% enantiomeric excess
`=("observed specific rotation")/("Specific ration of pure enantiomer")xx100`
observed specific rotation`=(3//4)/(100)xx(+16^(@))xx100=+12^(@)`