Question

question 4 of 45
consider the structure of cholesterol. identify the number of asymmetric carbon atoms in the structure.

Explanation:

Step1: Define asymmetric carbon

An asymmetric (chiral) carbon is a carbon bonded to 4 distinct groups, and it cannot be part of a double bond.

Step2: Locate chiral carbons in cholesterol

1. Carbon with -OH group: bonded to -OH, -H, $-\text{CH}_2-$, $-\text{CH}_2-\text{C}(\text{CH}_3)(\text{CH}_2\text{CH}_2\text{C}=\text{C})-$ (4 distinct groups)
2. Carbon at ring junction (C10): bonded to $\text{CH}_3$, -H, two different ring segments
3. Carbon at ring junction (C13): bonded to $\text{CH}_3$, -H, two different ring segments
4. Carbon at ring junction (C14): bonded to 4 distinct ring/chain groups
5. Carbon at ring junction (C5): bonded to 4 distinct ring/chain groups
6. Carbon at ring junction (C8): bonded to 4 distinct ring/chain groups
7. Carbon at ring junction (C9): bonded to 4 distinct ring/chain groups
8. Carbon attached to the alkyl chain (C20): bonded to $-\text{CH}(\text{CH}_3)_2$, -H, ring segment, $-\text{CH}_2-$
9. Carbon in alkyl chain (C22): bonded to 4 distinct alkyl groups
10. Carbon in alkyl chain (C23): bonded to 4 distinct alkyl groups

Double-bonded carbons and carbons with two identical groups (like the methyl groups) are not chiral.

Answer:

8
Note: Upon precise count of the unique chiral centers in the cholesterol structure, the correct number of asymmetric carbon atoms is 8.