For each pair of conformations shown, choose which is most stable. [If both conformations have the same number of gauche interactions, choose the one where the interactions are between smaller groups.]
(f)

Which conformation in each of the following pairs has the least strain energy?

(c)

Construct a graph, similar to Figure 3-11, of the torsional energy of 3-methylpentane along the C2―C3 bond.

e. Indicate which conformations are the most stable (lowest energy) and the least stable (highest energy).

Why is it incorrect to say that the dihedral angle shown is 120° or even 109°?

For each pair of conformations shown, choose which is most stable. [If both conformations have the same number of gauche interactions, choose the one where the interactions are between smaller groups.]

(e)

Which of the following structures represent the same compound? Which ones represent different compounds?

(f)

Construct a graph, similar to Figure 3-11, of the torsional energy of 3-methylpentane along the C2―C3 bond.

a. Place C2 in front, represented by three bonds coming together in a Y shape, and C3 in back, represented by a circle with three bonds pointing out from it.

b. Define the dihedral angle as the angle between the methyl group on the front carbon and the ethyl group on the back carbon.

Calculate the dihedral angle (θ) for the conformations shown.

(c)

Given the following Newman projection of ethane viewed down the $C_1-C_2$ bond, which bond-line structure does it represent? (Front carbon: three hydrogens; back carbon: three hydrogens; all staggered)