Org Chem Lec 4th Exam

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Created by
Christian Pilapil

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Cards (25)

  • Aromatic compounds

    Class of compounds structurally related to benzene
  • Aromatic compounds

    • Benzene
    • Benzaldehyde
    • Toluene
  • The term "aromatic" was originally used to describe fragrant substances
  • Benzene

    • Has 8 fewer hydrogens (C6H6) than the corresponding six carbon alkane (C6H14)
    • Unsaturated
    • Represented as a six-membered ring with alternating double and single bonds
  • Resonance in benzene

    • Benzene is a hybrid of two equivalent forms
    • True structure of benzene is somewhere in between the two resonance forms but is impossible to draw with our usual conventions
  • Wherever we find resonance, we find stability
  • Because of resonance, benzene is more stable and less reactive than a typical alkene
  • Electrophilic aromatic substitution

    A process in which an electrophile (E+) reacts with an aromatic ring and substitutes for one of the hydrogen atoms
  • Electrophilic aromatic substitution mechanism

    1. Electrophilic attack
    2. Formation of arenium ion intermediate
    3. Deprotonation
  • Electrophilic aromatic substitution reactions

    • Halogenation
    • Nitration
    • Sulfonation
  • Halogenation

    Substitution of a halogen atom, usually bromine or chlorine, for one of the ring hydrogens
  • Halogenation

    • Chlorobenzene
    • Bromobenzene
  • Nitration

    Substitution of a nitro (-NO2) group for one of the hydrogen atoms bonded to the ring
  • Aromatic nitration does not occur in nature but is particularly important in the laboratory because the nitro-substituted product (Ar-NO2) can be reduced to yield an amino-substituted product (Ar-NH2)
  • Sulfonation

    Formation of an arenesulfonic acid (Ar-SO3H) by heating an aromatic compound with concentrated sulfuric acid (H2SO4)
  • Uses of sulfonation

    • Preparation of synthetic detergents
    • Synthesis of sulfa-drug family of antibiotics
  • Phenols

    Aromatic compounds with a hydroxyl group (-OH) bonded to a benzene ring
  • Phenols

    • Phenol
    • Cresols
    • Thymol
    • Vanillin
    • Urushiol
  • Acidity of phenols

    • Phenols are weak acids, with pKa values of approximately 10
    • Most phenols are insoluble in water, but they react with strong bases such as NaOH and KOH to form water-soluble salts