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JEE Advanced levelSingle correct optionDifficulty 3 of 3nm044

What is the IUPAC name (2013 rules; lowest locants to all multiple bonds together, then to the double bond if there is a tie) of ?

  1. A2-methylhex-1-en-4-yne
  2. B2-methylhex-5-yn-1-ene
  3. C2-methylhex-1-en-5-yne
  4. D5-methylhex-5-en-1-yne

Answer: C

The six-carbon chain contains both multiple bonds. Numbered from the CH2= end the locants are ene 1, yne 5; from the HC-triple-bond end they are yne 1, ene 5. Both give the set {1,5}, so the double bond receives the lower locant. The CH2= end is C1, the methyl is on C2, and the name is 2-methylhex-1-en-5-yne.
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