JEE Main 2024 · 29 January · evening · Single correct · +4 / −1
According to IUPAC system, the compound
is named as
- (a) Cyclohex-2-en-1-ol
- (b) 1-Hydroxyhex-2-ene
- (c) Cyclohex-1-en-3-ol
- (d) Cyclohex-1-en-2-ol
Answer and solution
Answer (a) Cyclohex-2-en-1-ol
Solution
Chemistry ma’am · 4 steps
The OH group is the boss here: give its carbon number 1, then let the double bond take the lowest number left.
- Find the parent. The six carbons form a ring, so the parent is cyclohexane. The ring has one C=C double bond and one -OH group.
- Pick the principal group. -OH is the principal characteristic group, so the name ends in the suffix -ol. The double bond only changes -ane to -ene, giving cyclohexenol.
- Number the ring. The suffix group gets the lowest locant, so the carbon carrying OH is C1. Now go round the ring in the direction that reaches the double bond first. The double bond lies between C2 and C3, so its locant is 2.
- So. The name is cyclohex-2-en-1-ol, which is option (a).
The idea to keep. In a ring with a principal group, that group always sits at C1. Then number in the direction that gives the double bond the lowest locant.
Answer from the NTA final answer key. Solution by PrepWiser.