JEE Main 2025 · 4 April · evening · Single correct · +4 / −1
The IUPAC name of the following compound is:
HC≡C-CH₂-C(|)(OH)H-CH₂-CH=CH₂
- (a) 4-Hydroxyhept-6-en-1-yne
- (b) Hept-1-en-6-yn-4-ol
- (c) Hept-6-en-1-yn-4-ol
- (d) 4-Hydroxyhept-1-en-6-yne
Answer and solution
Answer (b) Hept-1-en-6-yn-4-ol
Solution
Chemistry ma’am · 3 steps
OH is at C4 from both ends, and so is the 1,6 set for the multiple bonds, so the double bond gets the 1.
- Principal group. The only functional group here is -OH, so it is named with the suffix -ol, not the prefix hydroxy. The chain holds all 7 carbons along with both multiple bonds, so the parent is a heptene-yne-ol.
Number from OH at Triple bond at Double bond at the HC≡C end C4 C1 C6 the CH₂=CH end C4 C6 C1 - Break the tie. Both directions give OH the locant 4 and the multiple bonds the set {1, 6}. When that happens, IUPAC gives the lower number to the double bond. So you number from the CH₂=CH end.
- So. Ene comes before yne in the name, and the -ol suffix goes last: Hept-1-en-6-yn-4-ol, option (b).
The idea to keep. When ene and yne get the same set of locants from either end, the double bond takes the lower number. Use hydroxy as a prefix only when a higher-priority group takes the suffix.
Answer from the NTA final answer key. Solution by PrepWiser.