Chapter 18.7, Problem 12CC

Interpretation Introduction

Interpretation:

• The structure of products formed in the reaction of ethoxy benzene with mixture of sulfuric acid and nitric acid has to be drawn.

• The mechanism for the formation of the major product by the same reaction has to be depicted.

Concept Introduction:

• Electrophiles are electron deficient species. In Electrophilic substitution reaction a group or atom in a compound is replaced by electrophile. This kind of reaction occurs predominantly in aromatic compounds. Electrophilic substitution reactions of aromatic compounds are known as aromatic electrophilic substitution reactions.

• Benzene is an electron rich Aromatic compound. It undergoes aromatic electrophilic substitution reaction. 

• The delocalized nature of pi electrons in benzene attributes a special property to benzene called resonance.

• The carbocation formed in Benzene (arene) ring Carbon is known as arenium carbocation. It is also known as sigma complex. It is the intermediate involved in all the aromatic electrophilic substitution reactions of benzene and related compounds.  It is stabilized by delocalization of pi electrons also known as resonance.

• Mixture of concentrated Nitric acid and concentrated Sulfuric acid is known as Nitrating mixture and used in nitration reaction of benzene and its related 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.