Chapter 18, Problem 42PP

Interpretation Introduction

Interpretation:

• The structure of major products formed in the reaction of given following compounds with fuming sulfuric acid has to be explained.

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.

• 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.