Chapter 18.8, Problem 13CC

Interpretation Introduction

Interpretation:

The regiochemical outcome for Nitration of 1,3-dinitrobenzene has to be illustrated.

Concept Introduction:

• The reaction of Nitration in aromatic compounds is insertion of ${\text{-NO}}_{\text{2}}$ group onto the aromatic ring. Mixture of concentrated Nitric acid and concentrated Sulfuric acid is known as Nitrating mixture and used in nitration of aromatic compounds.

• If the substituents on benzene Carbon are Electron rich groups they are known as activating groups. They are ortho- and para- directing groups because these groups when directly bonded to benzene Carbon increases the electron density at ortho and para positions. So they direct the incoming electrophile towards ortho and para position in electrophilic substitution reactions.

• If the substituents on benzene Carbon are Electron withdrawing groups they are known as deactivating groups. They are meta-directing groups because these groups when directly bonded to benzene Carbon decreases the electron density at ortho and para positions and so the incoming electrophile is directed towards meta position.

• The term Regioselectivity is referred as preference of a particular group to occupy a specific position in a compound. In case an aromatic ring has one or more than one substituents the position in the aromatic ring occupied by the incoming electrophile depends on various factors.

• Reactions always take place in such a way to furnish most stable products. In reactions of aromatic compounds the stability of a product is attributed to the number of resonance structures it forms.