MHT CET202523 Apr 2025Evening ShiftChemistryGeneral Organic ChemistryActual
Which of the following is structural formula of mesityl oxide?
Options
- A( CH ₃ )₂ CH - CH = CH - CO - CH ₃
- B( CH ₃ )₂ C = CH - CO - CH ₃
- C( CH ₃ )₃ C - CH = CH - CO - CH ₃
- D( CH ₃ )₂ CH - CH = CH - CO - CH ( CH ₃ )₂
Correct answer
B. ( CH ₃ )₂ C = CH - CO - CH ₃
Step-by-step solution
The compound mesityl oxide is systematically named 4-methylpent-3-en-2-one, indicating a five-carbon chain with a ketone at position 2, a double bond at position 3, and a methyl substituent at position 4. The correct structural formula must correspond to CH₃-CO-CH=C(CH₃)-CH₃ , which is 4-methylpent-3-en-2-one under standard numbering. Option A, ( CH₃ )₂ CH-CH=CH-CO-CH₃ , is 5-methylhex-3-en-2-one. Option B, ( CH₃ )₂ C=CH-CO-CH₃ , expands to CH₃-C(CH₃)=CH-CO-CH₃ and corresponds to 4-methylpent-3-en-2-one. Option C,