Chapter 11.10, Problem 15P

Interpretation Introduction

Interpretation:

The structural formula of the carbocation formed by protonation of either $\text{C-2 or C-3}$ in $\text{1,3-cyclopentadiene}$ is to be written for verifying that it is not allylic and hence not as stable as the one formed by protonation of either $\text{C-1 or C-4}$

Concept Introduction:

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The allyl group contains the unit ${\text{CH=CH-CH}}_{\text{2}}$ .

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A ${\text{sp}}^3$ carbon atom of an allyl group is the allylic carbon atom.

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Carbon atoms which are adjacent to the double bonded carbon atoms are the allylic carbon atoms

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Allylic carbocations are more stable than the corresponding alkyl carbocations because the vinyl group ${\text{(CH}}_2\text{=CH)}$ is a better carbocation-stabilizing substituent than alkyl groups.