Question

Explain: Stability ∝ extent of delocalization,give example

Answer 1

In resonance if there is delocalization of π Bond positive charge and negative charge or lone pair more is the stability.

Answer 2

Extent of delocalization basically means extent of resonance in a compound. It is the shifting of pi bonded or lone pair electrons throughout the compound, shared by the elements. For example, let's take benzene. It has three double bonds and has two kekule structures. It undergoes extensive resonance and all the pi electrons are delocalized, shifting around in cyclic resonance throughout the six carbon atoms. Thus, benzene is a really stable compound. Let's take another example, a three carbon structure with a double bond at one end and a positive charge on the carbon at the other end. This is called a allyl carbocation. It is EXTREMELY stable in terms of carbocation because of delocalized electrons. The pi bond is shifted, giving one Carbon a positive charge and the other carbon having the positive charge initially is now neutral. Neither of the two structures exists in reality, instead a hybrid of both exists. So, there are two partial double bonds between the three carbons and the positive charge is shared among the two terminal carbons. This distribution of charge stabilizes the molecule. Thus, delocalization increases stability.