Correct structure of γ-methylcyclohexane carbaldehyde is

Solution

Chemistry ma’am · 3 steps

Carbaldehyde means CHO sits right on the ring, so start lettering from the ring carbon carrying it.

1. Read the parent. Cyclohexanecarbaldehyde means a -CHO group joined directly to a ring carbon. The -CHO carbon itself is not part of the ring and gets no Greek letter.
2. Assign Greek letters. The ring carbon bearing -CHO is α, the next ring carbon is β, and the one after that is γ. So γ is ring position 3, and the name is the same as 3-methylcyclohexanecarbaldehyde.

   Option	How CHO is attached	Methyl position	Name
   (a)	directly on ring	ring C3 (γ)	3-methylcyclohexanecarbaldehyde
   (b)	via a CH₂	ring C3 of the cyclohexyl	2-(3-methylcyclohexyl)ethanal
   (c)	directly on ring	ring C2 (β)	2-methylcyclohexanecarbaldehyde
   (d)	via a CH₂	ring C2 of the cyclohexyl	2-(2-methylcyclohexyl)ethanal

3. So. Only (a) has -CHO on the ring and the methyl two carbons away from the α carbon, at γ.

The idea to keep. In Greek-letter names, α is the carbon attached to the functional group, not the functional group carbon itself. Then go β, γ outwards, one carbon at a time.

Answer from the NTA final answer key. Solution by PrepWiser.