Ch. 4 - Alkanes and CycloalkanesSee all chapters
All Chapters
Ch. 1 - A Review of General Chemistry
Ch. 2 - Molecular Representations
Ch. 3 - Acids and Bases
Ch. 4 - Alkanes and Cycloalkanes
Ch. 5 - Chirality
Ch. 6 - Thermodynamics and Kinetics
Ch. 7 - Substitution Reactions
Ch. 8 - Elimination Reactions
Ch. 9 - Alkenes and Alkynes
Ch. 10 - Addition Reactions
Ch. 11 - Radical Reactions
Ch. 12 - Alcohols, Ethers, Epoxides and Thiols
Ch. 13 - Alcohols and Carbonyl Compounds
Ch. 14 - Synthetic Techniques
Ch. 15 - Analytical Techniques: IR, NMR, Mass Spect
Ch. 16 - Conjugated Systems
Ch. 17 - Aromaticity
Ch. 18 - Reactions of Aromatics: EAS and Beyond
Ch. 19 - Aldehydes and Ketones: Nucleophilic Addition
Ch. 20 - Carboxylic Acid Derivatives: NAS
Ch. 21 - Enolate Chemistry: Reactions at the Alpha-Carbon
Ch. 22 - Condensation Chemistry
Ch. 23 - Amines
Ch. 24 - Carbohydrates
Ch. 25 - Phenols
Ch. 26 - Amino Acids, Peptides, and Proteins

Everyone draws their chairs different. How do you know if yours is right? 

Determining Which Chairs are Equivalent

Concept #1: The 3 important factors when drawing chairs

There’s only 3 things that you have to keep track of when you draw a chair.

  • Distance between groups
  • Cis vs. Trans
  • Equatorial Preference (determines conformers)

As long as these factors are the same between chairs, they are the same, regardless of what they look like!

Practice: Determine if the following pair of chairs are identical, conformers or different.

Practice: Determine if the following pair of chairs are identical, conformers or different.

Practice: Determine if the following pair of chairs are identical, conformers or different.

Additional Problems
Which pair of structures below are interconvertible by ring-flips? (1) A and B (2) A and C (3) B and C (4) All of them (5) None of them
Draw the ring flip for each of the following compounds:
myo-Inositol is a polyol (a compound containing many OH groups) that serves as the structural basis for a number of secondary messengers in eukaryotic cells. Draw the more stable chair conformation of myo-inositol.
Indicate the absolute configuration of each of the stereocenters in the molecule on the left and complete the chair form of the molecule on the template provided.
Do you expect cyclohexene to adopt a chair conformation? Why or why not? Explain.
For the following cyclohexane derivatives, draw the substituent groups on the two alternative chair conformations to indicate axial vs. equatorial positions. Be as careful as you can to clearly distinguish axial from equatorial in your drawing. If there is a difference in stability, draw a circle around the more stable conformation. If there is not any difference in stability, do not circle either chair form.
Consider the following tetra-substituted cyclohexane: (b) Determine which conformation is more stable.
Based on the molecule (A) shown below (bromine on C1 and chlorine on C5), answer the following questions. a) Draw the flipped chair conformation (B) of the molecule (A). Which one is more stable? Why (the name of specific interaction? b) Draw all other possible configurational isomers of (A) below. Bromine should be placed always in the axial position. In addition, circle “cis” or “trans” for each isomer and “R” or “S” for C1 and C5 configuration. c) Please circle the relationship(s) below between those chair conformations you drew in (b)?            Enantiomers, Diastereomers, Constitutional isomers, Conformational isomers
Draw the chair conformations for the following molecule. Circle the most stable conformer. If there is no difference in stability between the two conformers, then do not circle either of the chair conformations.
Identify the realationship in each of the following pairs. A) Constitutional Isomers B) Configurational Isomers C) Same molecule or Conformational Isomers
For the following structure:In the box provided finish the drawing (flip the chair). Predict where is the equilibrium shifted to (products or reactants); circle one:Left              Right            Neither
In the box provided, finish the drawing (flip the chair).Predict where is the equilibrium  shifted to (products or reactants); circle the appropriate arrow.