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An optically active compound enriched with R-enantiomer (60% ee) exhibited [α]D + 90°. If the, [α]D value of the sample is -135°, the ratio of R and S enantiomers would be:
- a)R:S = 1:19
- b)R:S = 19:1
- c)R:S = 1:9
- d)R:S = 9:1
Correct answer is option 'A'. Can you explain this answer?
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An optically active compound enriched with R-enantiomer (60% ee) exhib...
Given information:
- Optically active compound enriched with R-enantiomer (60% ee) exhibited []D 90.
- []D value of the sample is -135.
To find: Ratio of R and S enantiomers.
Calculation:
1. Calculation of specific rotation of R and S enantiomers:
- Specific rotation of a pure R-enantiomer = +90 (given)
- Specific rotation of a pure S-enantiomer = -90 (opposite sign of R-enantiomer)
2. Calculation of observed specific rotation of the sample:
- Observed specific rotation of the sample = -135 (given)
3. Calculation of the concentration of R and S enantiomers in the sample:
- Let [α]D be the observed specific rotation of the sample.
- Let c be the concentration of the sample in g/mL.
- Let l be the path length of the sample cell in dm.
Then,
[α]D = (α)cl
- where (α) is the specific rotation of the compound, c is the concentration of the sample, and l is the path length of the sample cell.
- Rearranging the equation:
c = [α]D / (α)l
- Substituting the given values:
c = -135 / (+90)l = -1.5/l
4. Calculation of the ratio of R and S enantiomers:
- Let x be the concentration of R-enantiomer in the sample.
- Then, the concentration of S-enantiomer in the sample is (1-x).
- The specific rotation of the sample is the weighted average of the specific rotations of R and S enantiomers:
[α]D = (αR)x + (αS)(1-x)
- Substituting the values:
-135 = (+90)x + (-90)(1-x)
- Solving for x:
x = 0.05
- Therefore, the concentration of R-enantiomer in the sample is 5% and the concentration of S-enantiomer in the sample is 95%.
- The ratio of R and S enantiomers is R:S = x:(1-x) = 0.05:0.95 = 1:19
Therefore, option 'A' is the correct answer.
- Optically active compound enriched with R-enantiomer (60% ee) exhibited []D 90.
- []D value of the sample is -135.
To find: Ratio of R and S enantiomers.
Calculation:
1. Calculation of specific rotation of R and S enantiomers:
- Specific rotation of a pure R-enantiomer = +90 (given)
- Specific rotation of a pure S-enantiomer = -90 (opposite sign of R-enantiomer)
2. Calculation of observed specific rotation of the sample:
- Observed specific rotation of the sample = -135 (given)
3. Calculation of the concentration of R and S enantiomers in the sample:
- Let [α]D be the observed specific rotation of the sample.
- Let c be the concentration of the sample in g/mL.
- Let l be the path length of the sample cell in dm.
Then,
[α]D = (α)cl
- where (α) is the specific rotation of the compound, c is the concentration of the sample, and l is the path length of the sample cell.
- Rearranging the equation:
c = [α]D / (α)l
- Substituting the given values:
c = -135 / (+90)l = -1.5/l
4. Calculation of the ratio of R and S enantiomers:
- Let x be the concentration of R-enantiomer in the sample.
- Then, the concentration of S-enantiomer in the sample is (1-x).
- The specific rotation of the sample is the weighted average of the specific rotations of R and S enantiomers:
[α]D = (αR)x + (αS)(1-x)
- Substituting the values:
-135 = (+90)x + (-90)(1-x)
- Solving for x:
x = 0.05
- Therefore, the concentration of R-enantiomer in the sample is 5% and the concentration of S-enantiomer in the sample is 95%.
- The ratio of R and S enantiomers is R:S = x:(1-x) = 0.05:0.95 = 1:19
Therefore, option 'A' is the correct answer.
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An optically active compound enriched with R-enantiomer (60% ee) exhibited [α]D + 90°. If the, [α]D value of the sample is -135°, the ratio of R and S enantiomers would be:a)R:S = 1:19b)R:S = 19:1c)R:S = 1:9d)R:S = 9:1Correct answer is option 'A'. Can you explain this answer?
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An optically active compound enriched with R-enantiomer (60% ee) exhibited [α]D + 90°. If the, [α]D value of the sample is -135°, the ratio of R and S enantiomers would be:a)R:S = 1:19b)R:S = 19:1c)R:S = 1:9d)R:S = 9:1Correct answer is option 'A'. Can you explain this answer? for Chemistry 2024 is part of Chemistry preparation. The Question and answers have been prepared according to the Chemistry exam syllabus. Information about An optically active compound enriched with R-enantiomer (60% ee) exhibited [α]D + 90°. If the, [α]D value of the sample is -135°, the ratio of R and S enantiomers would be:a)R:S = 1:19b)R:S = 19:1c)R:S = 1:9d)R:S = 9:1Correct answer is option 'A'. Can you explain this answer? covers all topics & solutions for Chemistry 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for An optically active compound enriched with R-enantiomer (60% ee) exhibited [α]D + 90°. If the, [α]D value of the sample is -135°, the ratio of R and S enantiomers would be:a)R:S = 1:19b)R:S = 19:1c)R:S = 1:9d)R:S = 9:1Correct answer is option 'A'. Can you explain this answer?.
An optically active compound enriched with R-enantiomer (60% ee) exhibited [α]D + 90°. If the, [α]D value of the sample is -135°, the ratio of R and S enantiomers would be:a)R:S = 1:19b)R:S = 19:1c)R:S = 1:9d)R:S = 9:1Correct answer is option 'A'. Can you explain this answer? for Chemistry 2024 is part of Chemistry preparation. The Question and answers have been prepared according to the Chemistry exam syllabus. Information about An optically active compound enriched with R-enantiomer (60% ee) exhibited [α]D + 90°. If the, [α]D value of the sample is -135°, the ratio of R and S enantiomers would be:a)R:S = 1:19b)R:S = 19:1c)R:S = 1:9d)R:S = 9:1Correct answer is option 'A'. Can you explain this answer? covers all topics & solutions for Chemistry 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for An optically active compound enriched with R-enantiomer (60% ee) exhibited [α]D + 90°. If the, [α]D value of the sample is -135°, the ratio of R and S enantiomers would be:a)R:S = 1:19b)R:S = 19:1c)R:S = 1:9d)R:S = 9:1Correct answer is option 'A'. Can you explain this answer?.
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