Q7-56E - Organic Chemistry (Mcmurry)

Question

Carbocations can be stabilized by resonance. Draw all the resonance forms that would stabilize each carbocation:

Step-by-Step Solution

Answer

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Step 1: Stability of carbocation

Carbocations are electron deficient species. So they are stabilized by electron donating groups and destabilized by electron withdrawing groups.

Step 2: Definition of Resonance

The electronic displacement of 𝛑 bonds present in the molecule that leads to the stabilization of the carbocation is termed as resonance. The greater the number of resonance forms, greater will be the stabilization of the carbocation.

Step 3: Resonance forms

The molecule contains conjugated double bonds. The carbocation formed shows three resonance structures. The resonance structures are shown below.

Step 4: Resonance forms

An electron withdrawing group is present in the molecule. Thus, there will be no resonance structure where the carbocation and the nitro group will be present on the same carbon atom. The three resonance structures formed are given below.

Step 5: Resonance forms

The methoxy group is an electron donating group. The lone pair of electrons present in oxygen stabilizes the carbocation formed adjacent to it. The three resonance structures are given below.