Q.Draw Newman's projections of two extreme conformations of ethane. Which conformation is more stable?

Ethane's two extreme conformations, viewed in a Newman projection along the C-C bond, are staggered (dihedral angle 60 degrees) and eclipsed (dihedral angle 0 degrees); the staggered form is more stable due to lower torsional strain.

In a Newman projection, we view the C-C bond of ethane (CH3-CH3) end-on: the front carbon's three C-H bonds are drawn as lines meeting at the centre point, and the back carbon's three C-H bonds are drawn as lines from behind a circle.

1. Staggered conformation: the three C-H bonds of the back carbon are positioned exactly between (at 60 degrees from) the three C-H bonds of the front carbon, when viewed down the C-C axis. This arrangement keeps the bonding electron pairs of the front and back C-H bonds as far apart as possible, minimising electron-electron repulsion (torsional strain).

2. Eclipsed conformation: the three C-H bonds of the back carbon directly line up with (are eclipsed by) the three C-H bonds of the front carbon (dihedral angle = 0 degrees). The C-H bonding pairs on adjacent carbons are close to each other, causing greater repulsion (torsional strain).

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