91Ó°ÊÓ

Resonance is a hypothetical process of movement of pi electrons due to the presence of conjugation. conjugation are of many types such as pi and positive charge, pi and Ion pair are on alternative position, pi and free radical are on alternative position, pi and pi electrons are on alternative position, ion pair and positive charge are on alternative position.

Resonating structures are hypothetical structures represent different positions of pi electrons at different time during resonance.

Given compound with a carbocation has conjugation in which double bond are on alternative position and one double bond is on alternative position to charge. Due to conjugation resonance occur and we get resonating structures. In the structure, pi electrons move towards positive charge due to which positive charge displace to that on from which electron are displaced (carbon 3)

In second structure, second double bond electrons move to 3rd carbon and due to this positive charge generated to 5th carbon.

In third structure, third double bond electrons move to 5th carbon and due to this, positive charge generated to 7th carbon.

In the fourth structure, double bond of side chainin in the second structure would move to the 7th carbon and due to this positive charge again come to first carbon as in 1st structure.

Thus, we get three resonating structures and alll are at equilibrium with each other. In first srtuctrue positive charge is on 1st carbon, in second structure positive charge is on 3rd carbon, in third structure positive charge is on 5th carbon, in forth structure, positive charge is on 7th carbon and in fifth structure, positive charge is agin on 1st carbon.