The product of the pericyclic reaction shown is to be predicted indicating whether the shift is a [5,5] suprafacial or an antrafacial process. Concept introduction: Sigmatropic rearrangements involve the migration of a Ïƒ bond present at the end or in the middle of the system across the Ï€ electron system from one position to another. They are represented by [m,n] where m and n represents the number of atoms between the bond being broken and the bond being formed in two directions. If even number of electron pair is involved then thermal reaction occur through antarafacial pathway and photochemical reactions occur through suprafacial pathway. If odd number of electron pair is involved then thermal reaction occur through suprafacial pathway and photochemical reactions occur through antarafacial pathway. To predict: The product of the pericyclic reaction shown indicating whether the shift is a [5,5] suprafacial or an antrafacial process.

Question

Consider the attached E2 reaction What happens to the reaction rate with each of the following changes?[1] The solvent is changed to DMF. [2] The concentration of −OC(CH3)3 is decreased. [3] The base is changed to −OH. [4] The halide is changed to CH3CH2CH2CH2CH(Br)CH3. [5] The leaving group is changed to I−.

Answer 1

Question

Chapter 30.SE, Problem 28AP

Interpretation Introduction

Interpretation:

The product of the pericyclic reaction shown is to be predicted indicating whether the shift is a [5,5] suprafacial or an antrafacial process.

Concept introduction:

Sigmatropic rearrangements involve the migration of a Ïƒ bond present at the end or in the middle of the system across the Ï€ electron system from one position to another. They are represented by [m,n] where m and n represents the number of atoms between the bond being broken and the bond being formed in two directions.

If even number of electron pair is involved then thermal reaction occur through antarafacial pathway and photochemical reactions occur through suprafacial pathway.

If odd number of electron pair is involved then thermal reaction occur through suprafacial pathway and photochemical reactions occur through antarafacial pathway.

To predict:

The product of the pericyclic reaction shown indicating whether the shift is a [5,5] suprafacial or an antrafacial process.

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Consider the attached E2 reaction What happens to the reaction rate with each of the following changes?[1] The solvent is changed to DMF. [2] The concentration of −OC(CH3)3 is decreased. [3] The base is changed to −OH. [4] The halide is changed to CH3CH2CH2CH2CH(Br)CH3. [5] The leaving group is changed to I−.

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