Naphthalene Electrophilic substitution Reaction at 1st position

Naphthalene Electrophilic substitution Reaction at 1st position

Example
Nitration of Naphthalene

Electrophilic aromatic substitution of  Naphthalene depends on the stability of the cationic intermediate. 

 If we compare the substitution at 1st and 2nd position , we notice that several resonance structures for each of the two cationic intermediates. 

However, the substitution resulting from 1st addition has one extra contributing structure that retains the unbroken benzene-like structure. Indicated by pink circle.

whereas the substitution at 2nd position does not have any benzenoid contributing structures.

Because of this the benzenoid bonding pattern is associated with aromatic stabilization at position 1st , we conclude that the preferred pathway of addition will be the one.