Question

Use a Newman projection about the indicated bond to draw the most stable conformer for each compound.

(a)$\text{3-methylpentane\hspace{0.17em}\hspace{0.17em}about\hspace{0.17em}\hspace{0.17em}the\hspace{0.17em}C2}-\text{C3\hspace{0.17em}\hspace{0.17em}bond}$

(b)$\text{3,3-dimethylhexane\hspace{0.17em}\hspace{0.17em}about\hspace{0.17em}\hspace{0.17em}the\hspace{0.17em}C3}-\text{C4\hspace{0.17em}\hspace{0.17em}bond}$

Short answer

Newman projections are often used in drawing conformations. In Newman’s projection, one views the bond end along the axis of connection. The front carbon is represented by the intersection of bonds, while the rear carbon appears as a circle.

Step-by-step solution

Newman projection

Newman projections are often used in drawing conformations. In Newman’s projection, one views the bond end along the axis of connection. The front carbon is represented by the intersection of bonds, while the rear carbon appears as a circle.

Using Newman projections to draw the most stable conformer

While looking from the direction of the arrow, it can be seen that the front carbon has a hydrogen atom pointing straight up, a methyl group pointing down and to the left, and a hydrogen atom pointing down and to the right. The back carbon has a methyl group pointing straight down, a hydrogen atom pointing up to the left, and an ethyl group pointing up to the right.

While looking from the direction of thearrow, it can be seen that the front carbon has a methyl group pointing straight down, an ethyl group pointing up to the left, and a methyl group pointing up to the right. The back carbon has a hydrogen atom pointing straight up, a hydrogen atom pointing down and to the left, and an ethyl group pointing down to the right.