Q2. Answer any TWO of the following parts: (a) Draw the two main conformations that exist for cyclohexane. Explain clearly why one conformer is more stable than the other. Using cis-1-ethyl-3-methylcyclohexane, as an example, explain how ring flipping occurs. Draw both conformers of cis-1-ethyl-3-methylcyclohexane and explain clearly which one predominates. (b) What is polarimetry? The specific rotation of (R)-carvone is - 61°. A chemist prepared a 750 mg mixture of (R)-carvone and its enantiomer in 10 ml of ethanol and placed the solution in a 10 cm polarimeter cell. The observed rotation was - 4.125°. Calculate the specific rotation for the above mixture. What is meant by enantiomeric excess? Then determine the % enantiomeric excess (% ee) in the mixture. (i) (ii) (iii) What % of the mixture is (R)-carvone and (S)-carvone?

Q2. Answer any TWO of the following parts: (a) Draw the two main conformations that exist for cyclohexane. Explain clearly why one conformer is more stable than the other. Using cis-1-ethyl-3-methylcyclohexane, as an example, explain how ring flipping occurs. Draw both conformers of cis-1-ethyl-3-methylcyclohexane and explain clearly which one predominates. (b) What is polarimetry? The specific rotation of (R)-carvone is - 61°. A chemist prepared a 750 mg mixture of (R)-carvone and its enantiomer in 10 ml of ethanol and placed the solution in a 10 cm polarimeter cell. The observed rotation was - 4.125°. Calculate the specific rotation for the above mixture. What is meant by enantiomeric excess? Then determine the % enantiomeric excess (% ee) in the mixture. (i) (ii) (iii) What % of the mixture is (R)-carvone and (S)-carvone?

Organic Chemistry

8th Edition

ISBN:9781305580350

Author:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. Foote

Publisher:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. Foote

Chapter26: Lipids

Section: Chapter Questions

Problem 26.24P: Following is a structural formula for cortisol (hydrocortisone). Draw a stereo-representation of...

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Following is a structural formula for cortisol (hydrocortisone). Draw a stereo-representation of this molecule showing the conformations of the five- and six-membered rings.
Perspective drawings of Chair and Boat Conformers fo Cyclohexane (C6H12). Note it is impossible to place all the carbons in the same plane without straining the bonds. Take two opposite carbons and pull both of them up to make one conformation adn then pull one of them down to make the other conformation. Can you inercovert one conformer int othe other without breaking any bonds? Explain why these represent conformers and not isomers.
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For trans‑1‑ethyl‑4‑isopropylcyclohexane, which structures represent the possible boat conformations?
How To Draw the Two Conformations for a Substituted Cyclohexane ?
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