Cyclohexane Conformations and Strain

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the major organic product of the bromination of cyclohexene?

  • Dibromocyclohexane with one chiral center
  • Trans-dibromocyclohexane
  • A racemic mixture of dibromocyclohexane (correct)
  • Cis-dibromocyclohexane

How would you characterize the configuration of the starting alkene, cyclohexene, prior to bromination?

  • E configuration
  • Neither E nor Z (correct)
  • Z configuration
  • Both E and Z configuration

What is the stereochemical relationship of the products formed from the hydroboration-oxidation of an alkene?

  • All products are meso compounds
  • Products could be racemic mixtures or diastereomers (correct)
  • All products are identical enantiomers
  • Products have alternating stereocenters

When performing bromination at −5°C in CCl4, what type of interactions mainly govern the reaction mechanism?

<p>Electrophilic additions (A)</p> Signup and view all the answers

In the context of stereochemistry, what should you include when drawing product structures from the given reactions?

<p>Complete structural representations including wedge-and-dash bonds (C)</p> Signup and view all the answers

Which structure is expected to have the most angle strain?

<p>Cyclopropane (C)</p> Signup and view all the answers

Among the following chair conformations of cis-1,3-dimethylcyclohexane, which two are in equilibrium?

<p>Conformation C and Conformation D (B), Conformation A and Conformation B (D)</p> Signup and view all the answers

What is the relationship between two conformations that are considered conformational enantiomers?

<p>They are mirror images of each other. (A)</p> Signup and view all the answers

What would be the expected difference in boiling points between two stereoisomers of 1,3-cyclohexanediol?

<p>One will have a higher boiling point than the other due to polarity. (A)</p> Signup and view all the answers

When considering two chair conformations of α-(+)-glucopyranose, which conformation is typically the more stable one at equilibrium?

<p>The conformation with equatorial substituents. (A)</p> Signup and view all the answers

How do stereo specific properties like solubility differ between stereoisomers?

<p>Solubility can vary based on the arrangement of functional groups. (C)</p> Signup and view all the answers

What type of strain is primarily associated with eclipsed conformations?

<p>Torsional strain (B)</p> Signup and view all the answers

What type of relationship exists if two chair conformations are identical?

<p>They are identical conformations of the same molecule. (C)</p> Signup and view all the answers

Flashcards are hidden until you start studying

Study Notes

Angle, Steric and Torsional Strain

  • Angle strain is caused by deviation of bond angles from ideal values (e.g., 109.5° in tetrahedral structures)
  • Steric strain is caused by repulsion between non-bonded atoms or groups
  • Eclipsing strain (torsional strain) is caused by repulsion between electron clouds of eclipsed bonds

Chair Conformations

  • Cis-1,3-dimethylcyclohexane has two chair conformations: the conformer with both methyl groups in equatorial positions and the conformer with one methyl group axial and one equatorial

Conformational Diastereomers

  • Conformational diastereomers are conformations of the same molecule that are non-superimposable mirror images
  • Conformational diastereomers have different energies and can be interconverted by rotations around single bonds

Cyclohexane Conformational Stability

  • In cis-1,3-dibromocyclohexane, the more stable conformer has both bromine substituents in equatorial positions

Relationship between Structures

  • Two structures might be conformations of the same molecule, conformational diastereomers, conformational enantiomers, or identical
  • If two structures are not conformations of the same molecule, they might be diastereomers, enantiomers

Properties of Stereoisomers

  • Stereoisomers can have different physical properties such as boiling point, density, solubility, optical rotation, and dipole moment
  • Taste can be influenced by chirality

α-(+)-Glucopyranose

  • α-(+)-Glucopyranose has two chair conformations, one more stable than the other
  • The more stable conformation has the largest number of bulky groups in equatorial positions

Bromination of Alkenes

  • Bromination of alkenes can lead to the formation of stereoisomers (diastereomers or enantiomers)
  • The stereochemistry of the product(s) depends on the configuration of the starting alkene (E or Z)

Hydroboration-Oxidation

  • Hydroboration-oxidation of alkenes can lead to the formation of alcohols
  • The stereochemistry of the product(s) depends on the configuration of the starting alkene

Hydrohalogenation

  • Hydrohalogenation of alkenes follows Markovnikov's rule: the hydrogen atom adds to the carbon atom with the most hydrogen atoms
  • The stereochemistry of the product(s) depends on the configuration of the starting alkene
  • The reaction can be influenced by the presence of a tertiary carbocation intermediate.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Quiz Team

Related Documents

Chapter 7 Practice Problems PDF

More Like This

Use Quizgecko on...
Browser
Browser