Fundamentals of Organic ChemistryChemistryGeneral Organic Chemistry
Identify the correct order of stability for the following carbocations: I. II. III.
Options
- AI > II > III
- BIII > I > II
- CI > III > II
- DII > III > I
Correct answer
D. II > III > I
Step-by-step solution
The stability of the given carbocations depends on the resonance (+M) stabilization provided by the adjacent oxygen atoms and the structural constraints of the rings. For structure II, the carbocation is stabilized by the +M effect of two adjacent oxygen atoms. The 6-membered ring allows the carbocation to adopt a planar geometry, maximizing orbital overlap. This makes it the most stable. For structure III, the carbocation is stabilized by the +M effect of only one adjacent oxygen atom. It is also planar and unstra