Transcript Chapter 1 Chemical Bonding and Chemical Structure

Chapter 16
The Chemistry of Benzene Derivatives
Morphine
Valium
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Aromatic Hydrocarbons
• Common sources: coal and petroleum
• Physical properties:
– Tend to be insoluble in water
– MP’s relatively high
– BP’s similar to molecules of similar structure and symmetry
• Each additional C atom adds 20-30°C to the BP
Common Nomenclature
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IUPAC Nomenclature
• Monosubstituted benzenes are named as other
hydrocarbons, with –benzene as the parent name
• Alkyl-substituted benzenes (arenes) are named in
two ways:
1) If the alkyl group has 6 or fewer carbons, it is
named as the substituent and the benzene ring
is the parent
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2) If the alkyl chain has more than 6 carbons, then the
benzene ring is the substituent and is called a
“phenyl” group
• A phenyl group can be represented a few different ways
• Don’t confuse a phenyl group with a benzyl group
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• Disubstitued benzenes can be named in two ways:
– Using o, m, or p
– Using numbers
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Nomenclature
• Principle groups
– If a substituent has highest priority, it is assumed to be on
carbon #1
– If none of the substituents has priority over the others, cite
them in alphabetical order
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• Numbering is required when more than two
substituents are present
• Recall priorities: carboxylic acid > anhydride >
ester > acid halide > amide > nitrile > aldehyde
> ketone > alcohol (phenol) > thiol > amine
16.1 Nomenclature of Benzene Derivatives
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Problems
• Name the following compounds:
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Electrophilic Aromatic Substitution
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Halogenation of Benzene
• Compare with the addition product for that of
an alkene
16.4 Electrophilic Aromatic Substitution Reactions of Benzene
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Mechanism of Halogenation
16.4 Electrophilic Aromatic Substitution Reactions of Benzene
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Mechanism of Halogenation
16.4 Electrophilic Aromatic Substitution Reactions of Benzene
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Recall:
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Three Mechanistic Steps in EAS
1. Generation of an electrophile
2. Nucleophilic reaction of the p electrons of the
aromatic ring with the electrophile
3. Loss of a proton from the carbocation to form
a substituted aromatic compound
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Problem
1) Monobromination of toluene gives 3 products. Draw the entire
mechanism for the formation of one product and draw the
other two.
2) Draw the product(s):
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Nitration of Benzene
• Mechanism:
16.4 Electrophilic Aromatic Substitution Reactions of Benzene
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Nitration of Benzene
16.4 Electrophilic Aromatic Substitution Reactions of Benzene
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Reduction of Nitro-substituted Benzene
Rings to Arylamines
• Also works with SnCl2
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Sulfonation of Benzene
• Mechanism:
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Problems
1) Draw the reactants required to produce the molecule below:
2) Draw the products for each step:
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Friedel-Crafts Alkylation of Benzene
• Compare the role of AlCl3 with that of FeBr3 in the
bromination reaction
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Limitations to Friedel-Crafts Alkylation
1) R must be an alkyl halide
2) The benzene ring cannot have amino or strongly electron
withdrawing substituents
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3) Reaction often does not stop after the first substitution
4) Rearrangement products are often produced
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• Hydride Shift:
• Alkyl Shift:
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Problems
• Give the products for the following reactions:
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