Part B
Cyclohexane exists in different types of conformations. The most stable among the conformers are the chair and boat conformations. The bond angles are approximately 109.5° in both the chair and boat forms of cyclohexane. The figure below shows the chair conformers (I and II) and the boat conformer (III). The conformations keep flipping; that is, the conformations undergo interconversions, as shown in the figure below:
In the conversion of the conformations of cyclohexane shown below, which of the following statements are true?
H H
/
C - C
/
H H
(I) In the conversion from I to II, C-H bonds on C2, C3, C5, and C6 become neither axial nor equatorial.
(II) In the conversion from I to II, steric strain is not introduced.
(III) In the conversion from I to III, all axial bonds become equatorial, and all equatorial bonds become axial.
(IV) In the conversion from I to II, at C1 and C4, C-H bonds are brought closer together, increasing repulsive interactions between them.
(V) In the conversion from I to II, the dihedral angle between the hydrogen atoms on adjacent carbon atoms increases.
(VI) In the conversion from III, the bond angle between the C-C-C bond of cyclohexane remains 109.5°.