Question

Draw Sawhorse projection for the eclipsed and staggered conformations of ethane. Which of these conformations is more stable and why?

Answer 1

Stability of conformation : In staggered form of ethane , the electron clouds of carbon-hydrogen bonds are as far apart as possible. Thus , there are minimum repulsive forces, minimum energy and maximum stability of the molecule. On the other hand , when the staggered form changes into the eclipsed form, the electron clouds of the carbon-hydrogen bonds come closer to each other resulting in increase in electron cloud repulsion. To check the increased repulsive forces , molecule will have to posses more energy and thus has lesser stability. Staggered form is more stable.