JEE MainChemistryGeneral Organic Chemistry
What is the correct IUPAC name of the compound whose structure consists of a five-membered carbon ring containing a ketone group ( >C=O ) and one double bond conjugated with it (i.e., between the and carbons). A hydroxyl ( -OH ) group is attached to the other allylic position, and a methyl group is attached to the saturated carbon atom situated between the hydroxyl-bearing carbon and the ketone carbon.
Options
- A3-Hydroxy-2-methylcyclopent-4-en-1-one
- B4-Methyl-5-oxocyclopent-2-en-1-ol
- C5-Methyl-4-hydroxycyclopent-2-en-1-one
- D4-Hydroxy-5-methylcyclopent-2-en-1-one
Correct answer
D. 4-Hydroxy-5-methylcyclopent-2-en-1-one
Step-by-step solution
The compound contains two functional groups: a ketone ( >C=O ) and a hydroxyl ( -OH ) group. According to the IUPAC priority order, the ketone has higher priority than the alcohol. Thus, the ketone is the principal functional group (taking the suffix '-one') and its carbon is assigned locant 1. The -OH group is treated as a substituent and is indicated by the prefix 'hydroxy'. The ring is numbered to give the double bond the lowest possible locant. Numbering towards the double bond gives it locant 2 (C2=C3). Number