Depto. Química Orgánica

AROMATIC NITRATION

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15/07/2017
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The nitration of an aromatic ring cannot be achieved with nitric acid alone.
One has to "activate" nitric acid by making it react first, as a base!!!, with sulfuric acid, of higher acidic strength.
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Even though nitric acid is usually considered as a quite strong acid, since acidity is a relative concept, HNO3 behaves as a base when confronted with stronger acids like sulfuric acid.
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Nitronum ion is an excellent electrophile that is able to be attacked by the pi cloud of benzene leading to nitrobenzene. Notice that sulfuric acid is recovered and thus a catalytic amount of it , not a stequiometric one, is needed.
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