Draw Newman projection, similar to Figure 3-25, down the C1-C6 bond in the equatorial conformation of methylcyclohexane. Show that the equatorial methyl group is also anti toC5. (Using your models will help.)

Newman projections are often used in drawing conformations. In Newman projection, one is viewing the C-C bond end on along the axis of connection. The front carbon is represented by the intersection of bonds from it, while the rear carbon appears as a circle.

Dihedral angle θ gives the identity of any conformation. It may be defined as the angle between C-H bonds on the front carbon atom and the C-H bonds on the back carbon atom in the Newman projection. A staggered conformation takes place at θ =180° ,where the two bulky groups are pointing in opposite direction known as the anti-conformation.

Chair conformation Newman projection

Looking down C1-C6 bond of the equatorial conformation, it can be seen that the methyl group is anti to C5 (red solid lines).