Question

Consider the following two compounds. These compounds are stereoisomers of 1, 2, 3-trimethylcyclohexane. One of these compounds has three chirality centers, while the other compound has only two chirality centers. Identify which compound has only two chirality centers and explain why.

Answer 1

(Refer to Image 1)

This compound has two chiral carbon which are $C-1$, $C-3$. $C-2$ is not chiral because it has two similar groups. The alkyl chain on both side containing $C_1$ and $C_3$ carbon have same configuration.

$C_1$ carbon has (Refer to Image 2)

$C_3$ carbon has (Refer to Image 3)

Thus $C-2$ is achiral having two same group

(Refer to Image 4)

This molecule has $3$ chiral carbon

$C_1$ carbon has (Refer to Image 5)

$C_3$ carbon has (Refer to Image 6)

Thus both the group containing $C_1$ & $C_3$ are different therefore along with $C_1$ & $C_3$, $C_2$ is also chiral.