Question

The IUPAC name of (CH$_3$)$_3$C–CH = CH$_2$ is

• A. 2,2-dimethylbut-3-ene
• B. 2,2-dimethylpent-3-ene
• C. 3,3-dimethylbut-1-ene
• D. hex-1-ene
• E. 2,2-dimethylhex-2-ene

Hint:

Always give lowest number to double bond before substituents.

Answer 1

The Correct Option is C

Concept: IUPAC naming involves:
• Selecting longest carbon chain containing double bond
• Numbering to give lowest number to double bond
• Identifying substituents

Step 1: Structure expansion \[ (CH_3)_3C-CH=CH_2 \] Central carbon attached to 3 methyl groups.

Step 2: Longest chain including double bond Chain: 4 carbons → butene

Step 3: Numbering Number from end nearer to double bond: \[ CH_2=CH- C(CH_3)_2 - CH_3 \] Double bond at position 1 → but-1-ene

Step 4: Substituents Two methyl groups at carbon 3 \[ \text{Name: } 3,3\text{-dimethylbut-1-ene} \]