See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# Delocalized π-electrons Analysis Delocalized π-electrons occur when π-electron density is distributed over more than two atoms through conjugation or aromaticity. ## (A) Cyclopentadienyl anion ($C_5H_5^-$) The cyclopentadienyl anion is **aromatic** with 6 π-electrons (satisfies Hückel's rule: $4n+2$ where $n=1$). The π-electrons are delocalized equally over all 5 carbon atoms in the ring. ✓ **Has delocalized π-electrons** ## (B) $CH_3CH_2NHCH=CH-CH_3$ The nitrogen atom has a lone pair that can participate in conjugation with the adjacent $C=C$ double bond: $$N-CH=CH-CH_3 \text{ (conjugated system)}$$ The lone pair on nitrogen overlaps with the π-electrons of the double bond, creating a resonance structure where negative charge extends from N to the β-carbon, delocalizing electrons. ✓ **Has delocalized π-electrons** ## (C) $(CH_3)_2C^+-CH_2-CH=CH_2$ The carbocation is separated from the double bond by a saturated $CH_2$ group. No conjugation or overlap between the carbocation p-orbital and π-system occurs—they are isolated by a $sp^3$ carbon. ✗ **No delocalized π-electrons** ## (D) $CH_3CH=CH-CH_2-OCH_3$ The double bond and oxygen are separated by a saturated $CH_2$ group. Although oxygen has lone pairs, the saturated carbon breaks conjugation, preventing π-electron delocalization. ✗ **No delocalized π-electrons** **Answer: (A) and (B)**