JEE Chemistry 2023 Question with Solution

Given: Testosterone, which is a steroidal hormone, has the following structure.

Find: The total number of asymmetric carbon atom/s in testosterone.

An asymmetric carbon atom (chiral center) is a carbon atom that is bonded to four different groups. Looking at the structure, we can identify the carbon atoms that have four different groups attached. These are chiral centers.

1. The carbon atom at the junction of the six-membered ring with the ketone group $C=O$ and the five-membered ring.
2. The carbon atom in the five-membered ring attached to the methyl group $CH_3$ and the hydroxyl group $OH$.
3. The carbon atom at the top of the other six-membered ring that forms a bridge.
4. The carbon atom at the bottom of the other six-membered ring that forms a bridge.
5. The carbon atom at the top of the six-membered ring with the double bond.
6. The carbon atom at the bottom of the six-membered ring with the double bond.

Therefore, there are a total of $6$ asymmetric carbon atoms in testosterone.

Given: We need to count the asymmetric carbon atoms in testosterone.

Find: Number of chiral centres.

Use the definition: a carbon atom is asymmetric if it is attached to four different groups. In the testosterone skeleton, the ring-junction and substituted bridge carbons satisfy this condition, while $sp^2$ carbons such as those in $C=C$ or $C=O$ do not.

From the identified centres in the structure, the total count is $6$.

So, the required numerical answer is $6$.