General Organic Chemistry

Introduction

• Focus on inductive effect, resonance, hyperconjugation.
• Organic Reagents: substances that react with organic molecules to give products.

Organic Reagents

• Types:
  • Electrophiles: Electron deficient, attracted to electron-rich areas.
    • Positively charged (e.g., CS3+, CL+, BR+, NO2+).
    • Neutral but become electron deficient (e.g., CO2, BCl3).
  • Nucleophiles: Electron-rich, donate electrons.
    • Lone pairs or negative charges (e.g., NH3, OH-).
    • Types: negatively charged, neutral, ambident nucleophiles.

Reaction Intermediates

• Types:
  • Carbocation: Carbon with a positive charge.
  • Carbanion: Carbon with a negative charge.
  • Free Radical: Unpaired electron on an atom.
  • Carbene: Carbon with two electrons or lone pair.
  • Nitrene: Nitrogen with unpaired electrons.

Electronic Effects

• Inductive Effect:

  • Permanent effect, electron withdrawing/donating groups impact electron density.
  • Minus I effect: Electron withdrawing (e.g., Cl, CN).
  • Plus I effect: Electron donating (e.g., CH3).
  • Applications: Stability of carbocations/carbanions, acidic/basic strength.

• Resonance:

  • Delocalization of electrons, increases stability.
  • Requires conjugation (alternating single and double bonds).
  • Types: pi-pi, pi-p, positive charge conjugation.

• Hyperconjugation:

  • Interaction between sigma bonds and pi systems.
  • Also known as "no-bond resonance" or sigma-pi conjugation.
  • Affects stability of alkenes based on the number of alpha hydrogens.

• Electromeric Effect:

  • Temporary, occurs in presence of a reagent.
  • Plus E effect: Electrophile-based.
  • Minus E effect: Nucleophile-based.

Organic Reactions

• Types of Reactions:
  • Substitution Reaction: Atom/group replaced by another.
    • Nucleophilic, Electrophilic, and Free Radical substitution.
  • Addition Reaction: Atoms/groups add to double or triple bonds.
  • Elimination Reaction: Atoms/groups removed, often forming double/triple bonds.
  • Rearrangement Reaction: Structural reorganization of atoms within a molecule.

Examples

• Substitution: Replacement of Cl in CH3Cl with OH-.
• Addition: HBr addition to alkenes, presence of peroxide changes outcome.
• Elimination: Removal of HBr from alkane forming alkene.
• Rearrangement: Conversion of primary to tertiary carbocation.

Conclusion

• Understanding these concepts is crucial for mastering organic chemistry reactions.
• These principles will recur throughout organic chemistry studies.