Question

Draw arrows to show the movement of electrons in going from one resonance contributor of pyrrole to the next.

Short answer

The structure of pyrrole is given below:

In this compound, there is a lone pair of electrons on the nitrogen atom. This is a five sided structure.

Step-by-step solution

Step-by-Step SolutionStep 1:Structure of pyrrole

The structure of pyrrole is given below:

In this compound, there is a lone pair of electrons on the nitrogen atom. This is a five sided structure.

Step 2: Movement of electrons in resonance structures of pyrrole

The electrons movement in resonance structures of pyrrole is shown in the figure given below:

Movement of electrons in pyrrole

The lone pair of electrons on nitrogen atom is moved and therefore, forms a double bond between nitrogen and ${\mathrm{C}}_1$. Also, the double bond between ${\mathrm{C}}_1$and ${\mathrm{C}}_2$shifts to ${\mathrm{C}}_2$and forms a negative charge on ${\mathrm{C}}_2$.

In the second structure, nitrogen will have a positive charge since its electrons are shifted. The negative charge on ${\mathrm{C}}_2$is shifted to form a bond between ${\mathrm{C}}_2$and ${\mathrm{C}}_3$. The role="math" localid="1652448690155" $\mathrm{\pi }$ bond between ${\mathrm{C}}_3$and ${\mathrm{C}}_4$is shifted to ${\mathrm{C}}_4$forming a negative charge on ${\mathrm{C}}_4$.

In the third resonance structure, the negative charge on ${\mathrm{C}}_4$is moved to ${\mathrm{C}}_4-\mathrm{N}$bond and therefore, forms a double bond. The bond between ${\mathrm{C}}_1$and nitrogen is shifted to ${\mathrm{C}}_1$and now the negative charge is on ${\mathrm{C}}_1$. This negative charge is shifted to ${\mathrm{C}}_1-{\mathrm{C}}_2$bond and the ${\mathrm{C}}_2-{\mathrm{C}}_3$bond is moved to ${\mathrm{C}}_3$forming a negative charge on ${\mathrm{C}}_3$.