Advanced Organic Chemistry

12

Aromaticity

LEARNING OBJECTIVES

By the end of this chapter you should be familiar with

• The concept of aromaticity, non-aromaticity, anti-aromaticity and homoaromaticity.
• The annulenes and their aromatic character.
• Aromaticity in charged rings, fused ring systems and heterocyclic rings.

12.1 INTRODUCTION

Organic compounds have been classified on the basis of their structure. Open-chain structures containing carbon–carbon single (C–C), double (C=C) and triple bonds are said to be aliphatic compounds. The term ‘aliphatic’ is derived from the Greek word for fat or oil. In alicyclic molecules, the carbon atoms form a cyclic structure. The generic name aromatic was given originally to a structurally diverse collection of compounds, which had one ...