4. Alkanes and Cycloalkanes

Which of the following is not a conformer of $\mathrm{butane}$?

Which conformer of ${\mathrm{tert}}^{-}-\mathrm{butylcyclohexanol}$ is the most stable at room temperature?

Given the Newman projection of $2_3$,$3_{\mathrm{dimethylbutane}}$ looking down the $C_2–C_3$ bond, where both methyl groups are gauche to each other, estimate the strain energy of this conformation.

Which of the following statements about the conformations of acyclic alkanes is true?

Which chair conformation of $1_{\mathrm{tert}-\mathrm{butyl}}-4-\mathrm{methylcyclohexane}$ has the lowest energy?

Which of the following conformers of $C_2{H}_6$ (ethane) has the highest energy?

Which of the following represents a gauche conformer of $C_2{H}_6$ (ethane) or $C_2{H}_5{F}_2$ (2-fluoroethanol)?

Which of the following best describes the process of translating a theoretical conformer of ethane from the staggered to the eclipsed conformation?

In 2-butanol, which group is gauche to the hydroxyl ($\mathrm{OH}$) group in its most stable staggered conformation?

Given the following conformations of 2-methylbutane: (A) anti (methyl and ethyl groups opposite), (B) gauche (methyl and ethyl groups $60°$ apart), (C) eclipsed (methyl and ethyl groups aligned), and (D) fully eclipsed (methyl and methyl groups aligned), rank them from lowest to highest energy.

Draw a perspective representation of the most stable conformation of 3-methylhexane.

For rotation about the C-3---C-4 bond of 2-methylhexane, do the following:

c. About which other carbon–carbon bonds may rotation occur?

d. How many of the carbon–carbon bonds in the compound have staggered conformers that are all equally stable?

Determine if the following pairof molecules is isomers or conformers?

In the lowest energy conformation of $C_2{H}_6$ (ethane), what is the dihedral angle between the two methyl groups?