Answer:
See the image Below
Explanation:
Single C-C bonds have free rotation and thus Newman Projections are quite useful for understanding the different 3D conformations of a molecule.
For any Newman Projection you have 2 bonded carbons, one in front of the other, therefore you rotate the bond by rotating the groups that are bonded to the carbons. i. e. in the 2-Methylpentane (viewing the C3-C4 bond) the carbons chosen are the 3rd and the 4th then you look to which are the other groups bonded; 2 H and an isopropyl for the 3rd one, and 2 H and a Methyl for the 4th one.
The different rotations of those groups receive different names:
- Anti Conformation: Main groups of the two Carbons are 180º apart from one another. Making this the most stable conformation of the molecule. (Taking into account steric effects)
- Gauche Conformation: Principal groups are 60º apart from each other. Since are 6 spaces between groups (360º/6)=60º. It is less stable than an Anti conformation due to the same reason.
- Eclipsed Conformation: The less stable conformation since the main groups are confronted.
