Question

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

• A. 2
• B. 3
• C. 4
• D. 1

Hint:

When scanning a carbon chain for chirality, look out for the terminal ends. A $\text{-CH(CH}_3)_2$ group at the end of a chain immediately makes that specific branch carbon achiral since it holds two identical methyl twins!

Answer 1

The Correct Option is B

Step 1: Draw the chain.
For 2-bromo-3,4,5-trimethylhexane, number the six carbons. C2 has Br, while C3, C4, C5 each carry a methyl.

Step 2: Test each carbon.
A chiral carbon has four different groups. C2 (H, Br, methyl, long chain), C3, and C4 each have four different groups, so they are chiral.

Step 3: Rule out C5.
C5 carries two identical methyl groups, so it is not chiral. That leaves three chiral carbons.
\[ \boxed{3,\ \text{option 2}} \]