Question

If this is Energy vs Dihedral angle graph of Butane, then I,II and III are respectively :

• A. Fully Eclipsed , Gauche , Anti
• B. Fully Eclipsed, Anti, Gauche
• C. Anti, Eclipsed, Gauche
• D. Gauche, Anti, Eclipsed

Answer 1

The correct option is B

Fully Eclipsed, Anti, Gauche

I and VII, II and VI, III and V are same.

Energy vs. Dihedral agle or angle of rotation diagram:

Mainly three conformational isomers of butane

Stability order: Staggered $>$ Gauche (Skew) $>$ Eclipsed.

All other infinite possibilities in between staggered and eclipsed conformations are known as skew (Gauche) form.