Increasing order of reactivity of the following compounds for S_{N}1  substitution is :

  • Option 1)

    (B)<(C)<(D)<(A)

  • Option 2)

    (B)<(C)<(A)<(D)

  • Option 3)

    (B)<(A)<(D)<(C)

  • Option 4)

    (A)<(B)<(D)<(C)

Answers (1)

 

Mesomeric or Resonance effect -

Migration of lone pair or \pielectron in a conjugated system.

- wherein

It is a permanent effect

 

 

Stability due to resonance -

More the no of resonating structure more is the stability.

- wherein

 

 

 

 

 

Hyperconjugation or σ-π resonance or Baker and Nathan effect -

The conjugation between \alpha C-H sigma bond and adjacent  multiple bond or carbocation is called Hyperconjugation.

- wherein

It is permanent effect.

 

 

 

Application of Hyperconjugation -

More is the no of Hyperconjugation  structure more is the stability of carbocation

- wherein

 

 

(a)  

 

(b) 

 

(c)

(d)  

order \Rightarrow\:\:\:\:b<a<d<c

1^0 < 3^0

+M>delocalisation >3^{0}>1^{0}


Option 1)

(B)<(C)<(D)<(A)

Option 2)

(B)<(C)<(A)<(D)

Option 3)

(B)<(A)<(D)<(C)

Option 4)

(A)<(B)<(D)<(C)

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