Question

What is the most stable conformer for 3-methylhexane, viewed along the `C_3-C_4` bond using Sawhorse projections?

Answer 1

The structure of 3-methylhexane is

Start by drawing a sawhorse template.

C-3 will be at the lower left, and C-4 will be at the upper right.

The groups attached to C-3 are CH₃CH₂, CH₃, and H. Attach these groups to C-3, with CH₃CH₂ at the top.

The groups attached to C-4 are CH₃CH₂, H, and H. Attach these groups to C-4, with CH₃CH₂ at the bottom.

You want the two big ethyl groups to be anti to each other, because this minimizes their repulsions.

The most stable conformation of 3-methylhexane is

Here's an image from a molecular modelling program. Can you see the similarity?