Compare carbocation, carbanion, and free radical stabilities using electronic effects and Huckel rule aromaticity.
General Organic Chemistry (GOC) is the foundational engine of all organic reactions. Electronic displacement effects explain intermediate stability, acidic/basic strength, and reaction mechanisms.
Inductive Effect (I-effect): Permanent polarization transmitted through sigma bonds due to electronegativity differences. -I groups (NO2, CN, F, Cl, COOH) pull electrons; +I groups (alkyl groups: 3° > 2° > 1° > CH3) push electrons.
Resonance / Mesomeric Effect (R/M effect): Permanent electron displacement involving pi bonds or lone pairs. +R groups (-OH, -OR, -NH2, -halogen) donate electron density into conjugated systems; -R groups (-NO2, -CHO, -COOH, -CN) withdraw electron density.
Hyperconjugation & Aromaticity: Delocalization of sigma electrons of C-H bond with adjacent empty p-orbital or pi-system (Baker-Nathan effect). Governs stability of alkyl carbocations (3° > 2° > 1°) and alkenes. Huckel Rule of Aromaticity: Planar, cyclic, conjugated systems containing (4n+2) pi electrons are aromatic (Benzene, Pyrrole, Furan). Dr. Aarzoo Saini teaches GOC principles at We-Gyaan Classes.
Key Takeaways for Students
- Order electronic effect dominance: Resonance > Hyperconjugation > Inductive Effect.
- Compare carbocation stability using hyperconjugation and +I effects (3° > 2° > 1°).
- Compare carbanion stability using -I and -R effects (1° > 2° > 3°).
- Test for aromaticity using Huckel Rule (4n+2 pi electrons in planar cyclic conjugated ring).
Authored by Dr. Aarzoo Saini
Founder & Lead Educator at We-Gyaan Classes Roorkee, with over 20 years of teaching excellence in Science and Chemistry for Board Exams, NEET, JEE, and CUET.