Question

How many chiral carbon atoms are present in 2-Iodo-3, 4, 5-trimethylhexane ?

• A. \(2\)
• B. \(3\)
• C. \(4\)
• D. \(1\)

Hint:

A chiral carbon has four different groups attached.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
A chiral carbon is sp3 hybridised and bonded to four different groups. First draw the structure: \(\text{CH}_3-\text{CH(I)}-\text{CH(CH}_3)-\text{CH(CH}_3)-\text{CH(CH}_3)-\text{CH}_3\) (carbons 1 to 6).

Step 2: Test carbons one by one:
C-1 and C-6 are \(\text{CH}_3\) groups, so they are not chiral.
C-2 has H, I, \(\text{CH}_3\) and the rest of the chain: chiral.
C-3 has H, \(\text{CH}_3\), C-2 side and C-4 side, all different: chiral.
C-4 has H, \(\text{CH}_3\), C-3 side and C-5 side, all different: chiral.
C-5 has H, \(\text{CH}_3\) (the substituent), \(\text{CH}_3\) (C-6) and C-4 side. Two groups are the same methyl, so it is not chiral.

Step 3: Count:
Chiral carbons are C-2, C-3 and C-4, which is 3 in total.

Final Answer:
Three chiral carbons, option (B). \[ \boxed{3} \]