When the aromatic hydrocarbon naphthalene reacts with nitric and sulfuric acids, two compounds containing one nitro group are formed. What are the structures of these two compounds?
1 Answer
Dec 27, 2014
The two compounds are 1-nitronaphthalene and 2-nitronaphthalene.
The nitration of naphthalene is an electrophilic aromatic substitution.
It involves the attack of nitronium ion, NO₂⁺, on the aromatic system.
Attack at C-1
Nitration at C-1 produces a carbocation that has 7 resonance contributors.
Four of these ( 1, 2, 6, and 7) preserve the aromaticity (six π electrons) of the second ring.
Attack at C-2
Nitration at C-2 produces a carbocation that has 6 resonance contributors.
Two of these (1 and 6) preserve the aromaticity of the second ring.
So attack at C-1 is favoured, because it forms the most stable intermediate.
The major product is 1-nitronaphthalene. The minor product is 2-nitronaphthalene.
