(+)2-butanol has [ θ ] λ 25 = 13. 9 ∘ . A sample of 2-butanol containing both the enantiomers was found to have specific rotation value of − 3. 5 ∘ under similar condition. The percentage of the ( + )

Question

(+)2-butanol has [ θ ] λ 25 = 13. 9 ∘ . A sample of 2-butanol containing both the enantiomers was found to have specific rotation value of − 3. 5 ∘ under similar condition. The percentage of the ( + ) and ( − ) enantiomer present in the sample are, respectively :

TestHub · Accepted Answer

Explanation Question:

The question asks about the d and ℓ (+ and –) enantiomers in the sample.

Concept:

This question is based on optical purity and enantiomeric excess.

Solution:

% optical purity $= \frac{o b ser v e d s p ec i f i c R o t a t i o n}{s p ec i f i cro t a t i o n o f p u re E nan t i o m er} \times 100$

$\displaylines = \frac{- 3.5}{13.9} \times 100 = 25.18$

% racemic mixture (d + ℓ mixture) is:

$100 - 25.18 = 74.82$

The total percentage of ℓ (– enantiomer) is:

$\frac{74.82}{2} + 25.18 = 37.41 + 25.18 = 62.59$

The total percentage of d (+ enantiomer) is:

$\frac{74.82}{2} = 37.41$

Final Answer: (A)

Chemistry - STEREO ISOMERISM Question with Solution | TestHub

Options:

Doubts & Discussion