cyclohexane chair forms

MS 900 - Conformers and Cyclohexane Practice Submitted by Matt on August 6, 2011.

Textbook and Chapter: Carey and Giuliano 8th Ed. (2010), Chapter 3

Keywords: conformational analysis, cyclohexane chair forms

Description: Reviews cyclohexane chair forms and conformations of butane:

  • Which dimethylcyclohexane is more stable 1,2-cis or 1,2-trans? Why?
  • Drawing chair forms
  • E2 anti-coplanar conformation and chair forms
  • Newman projects

Total Problems: 4

Problem # 661

The proton NMR of cyclohexane gives only one peak when the NMR is run at room temperature. 

But when the temperature is lowered to -100 ºC the proton NMR spectrum shows two peaks. Explain.

Problem # 319

For a molecule to undergo an E2 reaction, the leaving group and the beta-proton must be in an anti-coplanar conformation (one atom straight up, the other straight down). Based on this, which compound undergoes E2 reaction with KOtBu faster? Why?


Problem # 318

Two stereoisomers of trimethylcyclohexane are shown below (compounds A and B). Compare cyclohexane chair forms to determine which isomer has a lower heat of combustion. Explain your reasoning.


Problem # 317


α-D-Glucose is shown below. Draw its two chair forms. Which conformation is more stable? Explain.

I recommend using the common convention wedge = "up" and dash = "down."