The two chair conformations of cyclohexane-d 1 in which one hydrogen atom has been replaced by a deuterium atom are to be drawn. Which of the two conformers is expected to be present in greater abundance is to be determined. Concept introduction: Cyclohexane exists in two chair conformations which interconvert through a chair flip. The hydrogen atoms in cyclohexane are either in axial or equatorial positions. During chair flip, the hydrogens that were in an axial position are in the equatorial position and vice versa. However, the two chair conformers of cyclohexane are indistinguishable as all atoms bonded to the ring carbons are small hydrogen atoms. In substituted cyclohexane, the larger size of the substituent atom or group reduces the stability of one of the conformations. Bulky groups require more space than hydrogen atoms and, therefore, are more stable in the equatorial position. A substituent in axial position is close to the two hydrogen atoms in axial positions on the same side of the ring. There are no such hydrogens in close proximity to a substituent in an equatorial position. This makes the equatorial conformer more stable.

Question

Want to see the full answer?

Answer 1

Question

Chapter 4, Problem 4.9P

Interpretation Introduction

Interpretation:

The two chair conformations of cyclohexane-d1 in which one hydrogen atom has been replaced by a deuterium atom are to be drawn. Which of the two conformers is expected to be present in greater abundance is to be determined.

Concept introduction:

Cyclohexane exists in two chair conformations which interconvert through a chair flip. The hydrogen atoms in cyclohexane are either in axial or equatorial positions. During chair flip, the hydrogens that were in an axial position are in the equatorial position and vice versa. However, the two chair conformers of cyclohexane are indistinguishable as all atoms bonded to the ring carbons are small hydrogen atoms.

In substituted cyclohexane, the larger size of the substituent atom or group reduces the stability of one of the conformations. Bulky groups require more space than hydrogen atoms and, therefore, are more stable in the equatorial position. A substituent in axial position is close to the two hydrogen atoms in axial positions on the same side of the ring. There are no such hydrogens in close proximity to a substituent in an equatorial position. This makes the equatorial conformer more stable.

Expert Solution & Answer

Want to see the full answer?

Check out a sample textbook solution

See solution

Students have asked these similar questions

Wintergreen from Aspirin: 1. In isolating the salicylic acid, why is it important to press out as much of the water as possible? 2. Write the mechanism of the esterification reaction you did. 3. What characteristic absorption band changes would you expect in the IR spectrum on going from aspirin to salicyclic acid and then to methyl salicylate as you did in the experiment today? Give approximate wavenumbers associated with each functional group change. What signals appeared/disappeared/shifted that indicate that you have your intended product and not starting material? What other impurities are present in your product and how do you know?

Synthesis of ZybanⓇ: 1. Write a mechanism for the bromination of m-chloropropiophenone. Br₂ CH2Cl2 Cl Br 2. Give the expected m/z (to a round number) for the molecular ion from the product above (including isotopic peaks). 3. What signals appeared/disappeared/shifted that indicate that you have your intended product and not starting material? What other impurities are present in your product and how do you know?

Synthesis of Ibuprofen-Part 2: 1. Some pain relievers including ibuprofen (MotrinⓇ) and naproxen (Aleve®) are "α-arylpropanoic acids." Look up the structure of naproxen (AleveⓇ), another a-arylpropionic acid. Using the same reactions that we used for making ibuprofen, show how to make naproxen from the compound below. Show all intermediates and reagents in your synthesis. Show how you would prepare ibuprofen starting from p-isobutylbenzene rather than p-isobutylacetophenenone. What reaction steps would need to change/add? 3. What signals appeared/disappeared/shifted that indicate that you have your intended product and not starting material? What other impurities are present in your product and how do you know?