🧪

Basic Organic Chemistry

Jun 18, 2025

Overview

This lecture explains the essential basics before starting organic chemistry, especially carbon, inductive effect, resonance, and the main nomenclature and reaction chart in simple Hindi.

Special Features of Carbon

  • Carbon is tetravalent, meaning it always forms 4 bonds.
  • When oxygen is attached to carbon, the first oxygen is always in a double bond.
  • Complete the remaining bonds of carbon with hydrogen.

Inductive Effect (I Effect)

  • Inductive effect means the shift of electrons towards the electronegative atom.
  • Electron donating is called plus I (electron releasing), electron withdrawing is called minus I.
  • Plus I: Alkyl groups (CH₃), Minus I: NOâ‚‚, F, Cl, Br, I, etc.

Applications of Inductive Effect

  • Stability of reaction intermediate (carbocation): 3° > 2° > 1° > methyl.
  • Stability increases with plus I, reaction becomes faster.
  • Aldehyde/ketone reactivity: plus I effect decreases reactivity.
  • Acidic strength: plus I decreases, minus I increases.

Resonance Effect

  • Plus R effect: single bond groups on benzene ring send electrons down (ortho and para direction).
  • Minus R effect: double bond groups and oxygen-containing groups take electrons up (meta direction).
  • Plus R: ortho/para directing (Ram-Om light trick), minus R: meta directing (Ravan-Meghnath trick).

Main Nomenclature and Structure

  • Benzyl: a CHâ‚‚ attached to a benzene ring.
  • Allyl: CHâ‚‚=CH-CHâ‚‚- group.
  • Vinyl: CHâ‚‚=CH- group.
  • Phenol: –OH on benzene ring.
  • Ether: R-O-R', Ester: RCOOR', Amide: RCONHâ‚‚ etc.

Important Reaction Chart

  • Alkene + Clâ‚‚/hv → Chloro-alkane.
  • Alcohol + SOClâ‚‚ → Alkyl chloride.
  • Alcoholic KOH does dehydrohalogenation, forming double/triple bonds.
  • Benzene + HNO₃/Hâ‚‚SOâ‚„ → Nitrobenzene, Benzene + SO₃/Hâ‚‚SOâ‚„ → Sulfonic acid.

Dipole Moment

  • p = q × d (Dipole moment = charge × distance).
  • Double bond length is less than single bond, affecting dipole moment.

Key Terms & Definitions

  • Tetravalency — Carbon forming 4 bonds.
  • Inductive Effect — Electron shift towards electronegative atom.
  • Resonance Effect — Electron delocalization (sharing).
  • Carbocation — Positively charged carbon intermediate.
  • Plus/Minus I/R Effect — Electron releasing or withdrawing nature.

Action Items / Next Steps

  • Memorize definitions of plus/minus I and R effects.
  • Memorize reaction intermediate and nomenclature charts.
  • Practice given questions (more acidic, more reactive, etc.).
  • Read the relevant chapter of the book for the next lecture.

Full transcript