The two tetrahedral methyl groups can rotate about the carbon-carbon bond axis yielding several arrangements called conformers. The extreme conformations are staggered and eclipsed conformations. There can be number of other arrangements between staggered and eclipsed forms and their arrangements are known as skew forms.
Eclipsed conformation:
In this conformation, the hydrogen of one carbon atom is directly behind those of the other. The repulsion between the atoms is maximum and it is the least stable conformer.
Staggered conformation:
In this conformation, the hydrogen’s of both the carbon atoms are tir apart from each other. The repulsion between the atoms is minimum and it is the most stable conformer.
Skew formation:
The infinite numbers of possible intermediate conformations between the two extreme conformations are referred as skew conformations.
The stabilities of various conformations of ethane are Staggered > Skew> Eclipsed
The potential energy difference between the staggered and eclipsed conformation of ethane is around 12.5 kJ mol-1 HBr The various conformations can be represented by Newman projection formula.
Newman Projection formula for Ethane:
