Chapter 16, Problem 78CP

(a)

Interpretation Introduction

Interpretation:

The plausible mechanism for the formation of the product B has to be proposed.

Concept introduction:

There are mainly three types of pericyclic reactions,

1. 1) Electrocyclic reactions
2. 2) Cycloaddition reactions
3. 3) Sigmatropic reactions

  In a cycloaddition reaction “ two new sigma-bonds are formed or brocken”

Click reaction:

Azide reaction with alkyne in the presence of ${\text{CuSO}}_{\text{4}}$ and provides trazole as a product.

(b)

Interpretation Introduction

Interpretation:

The structure of compound C has to be drawn.

Concept introduction:

There are mainly three types of pericyclic reactions,

1. 1) Electrocyclic reactions
2. 2) Cycloaddition reactions
3. 3) Sigmatropic reactions

  In a cycloaddition reaction “ two new sigma-bonds are formed or brocken”

Click reaction:

Azide reaction with alkyne in the presence of ${\text{CuSO}}_{\text{4}}$ and provides trazole as a product.

(c)

Interpretation Introduction

Interpretation:

The reason for decrease in rate if the alkyne A is replaced by alkynes from D-F has to be determined.

Concept introduction:

Angle strain: The strain experienced because of existence of the non-bonded interactions of the atoms which are placed spatially close to each other is called the angle strain.

The angle strain will be very much low for $\text{sp}$-hybridised carbon in linear alkyne but is more in cyclic alkyne.