Question

Select the correct stability order of the conformation /Rotamers/ Rotational isomers of Ethane Molecule

 (a) Partially Eclipsed > Fully Eclipsed > Anti-staggered > Skew or Gouche

 (b) Skew or Gouche > Partially Eclipsed > Fully Eclipsed > Anti-staggered

 (c) Anti-staggered > Skew or Gouche > Partially Eclipsed > Fully Eclipsed

 (d) Fully Eclipsed > Anti-staggered > Skew or Gouche > Partially Eclipsed

Answer 1

The correct answer is (c) solution::

The isomers which can be produced by the free rotation about single bond are known as conformation /Rotamers/ Rotational isomers and this phenomenon is called as conformational analysis These isomers can be represented by

1. Sawhorse projection

2. Newman’s projection formula

3. A staggered conformer is more stable than an eclipsed conformer as the latter involves unfavourable energy interactions between atoms.

4. In conformational analysis (energetics study of different rotational conformers or rotamers), structures are represented by *Newman projection * (atoms and bonds are viewed along the axis of rotation).