Question

Draw sawhorse projections for the most stable and the least stable conformations of butane

Answer 1

Staggered conformations about carbon-carbon single bonds are more stable (have a lower potential energy) than the corresponding eclipsed conformations. The higher energy of eclipsed bonds is known as eclipsing strain. In butane the gauche-conformer is less stable than the anti-conformer by about 0.9 kcal/mol.