Organic chem exam 1

Organic chem exam 1

1. Chapter 17

   • CONJUGATION
     • the overlap of 3 or more p orbitals that are aligned or parallel leading to the delocalization of electrons
     • benzene is cyclically conjugated
       • benzene is very stable and doesn't react with much
   • AROMATICITY
     • molecules
       • must be cyclic
       • have a p orbital on every atom in the ring
       • be planar
       • have 4n+2π electrons
     • Anti aromatic
       • fit all criteria but not the 4n+2π just 4n
       • destabilized by conjugation
     • Lone pairs
       • must go in to an unhybridized orbital if there is a π bond
       • can go wherever makes the molecule aromatic if next to a sigma bond

2. Chapter 18

   • REACTIONS
     • aromaticity prevents addition
     • aromatic compounds undergo electrophilic substitution
       • the addition of the electrophile is the rate determining step.
         • breaks aromaticity
   • MECHANISMS
     • Halogenation
       • Cl2, AlCl3 OR Br2, FeBr3 makes electrophile
         • base removes the substituted H
     • Nitration
       • nitronium ion is electrophile
         • O=N=O
           • adds NO2
     • Sulfonation
       • electrophile is a silver trioxide cation
         • S double bonded to 2 O and and OH
           • adds SO3H
     • Friedel-Crafts
       • creates a benzylic ketone
         • uses electrophilic substitution
       • acylation
       • alkylation
         • electrophile is a carbocation
           • watch out for carbocation rearrangement
   • SUBSTITUATED BENZENE
     • Resonance effect
       • electron donating
         • places negative on the ring
         • ortho/para director
       • electron withdrawing
         • places positive on the ring
         • meta director
   • SnAr reaction
     • nucleophilic aromatic substitution
       • nucleophile takes the place of a leaving group
       • nucleophiles: OR, SR, CN