In the presence of iron, an ___________________reaction is observed between benzene and bromine.
electrophilic aromatic substitution
Iron tribromide is a is a __________________that interacts with Br2 and generated Br+ which is sufficiently electrophilic to be attacked by benzene.
Lewis acid
Electrophilic aromatic substitution involves two steps.
1- formation of the sigma complex 2- deprotonation to restore aromaticity
Sulfur trioxide is a very powerful
electrophile
Sulfur trioxide is present
in fuming sulfuric acid.
Benzene reacts with SO3 in a reversible process called
sulfonation
A mixtrue of sulfuric acid and nitric acid produces the
nirtonium ion (NO2+)
Benzene reacts with the nitronium ion in a process called
nitration
A nitro group can be reduced to an
amino group
Friedel-Crafts alkylation enables the installation of an alkyl group on
an aromatic ring
When choosing an alkyl halide, the carbon aton connect to the halogen in a Friedel-Crafts alkylation must be
SP3 hybridized.
When treated with a Lewis acid, an acyl chloride will generate an
acylium ion, which is resonacne stabilized and not susceptible to carbocation rearrangements.
When a Friedel-Crafts acylation os followed by a Clemmensen reduction the net result is the installation of an
alkyl group.
An aromatic ring is activated by a methyl group with is an
ortho-para director
all activators are
ortho-para directos
A nitro group
deactivates an aromatic ring and is a Meta director
Most deactivators are
meta directors
Strong activators are characterized by the presence of a
lone pair immediately adjacent to the aromatic ring.
Strong deactivators are powerfully electron-withdrawing
either by resonance or induction
When multiple substituents are present the more powerful
activating groups dominates the directing effects
In a nucleophilic aromatic substution reaction the aromatic ring is attacked
by a nucleophile.
A nucleophilic aromatic substitution has three requirements
1- the ring must contain a powerful electron-withdrawing group (usually a nitro group).2- the ring must contain a leaving group. 3- the leaving group must be either ortho or para to the electron-withdrawing group.
An elimination-addition reaction occurs via a
benzyne intermediate.
Which of these is the rate-determining step in the electrophilic aromatic substitution of benzene?
Formation of the sigma complex
What group os incompatable with Friedel-Crafts reaction?
Nitro groups