Organic Chemistry – Some Basic Principles and Techniques

The order of relative stability of the contributing structure is : [figure] Choose the correct answer from the options given below :

1. I = II = III
2. I > II > III
3. III > II > I
4. II > I > III

Answer

(2) I > II > III

Solution

I: neutral, every atom has a complete octet ⇒ most stable

II: charge-separated; on O (more electronegative atom) ⇒ less stable than I

III: charge-separated; on C and on the more electronegative O (O has only a sextet) ⇒ least stable

∵ neutral form > charge-separated forms, and prefers the more electronegative atom

∴ I > II > III

Answer: (2)