THE NITRATION OF PHENYL-SUBSTITUTED HETEROCYCLES

This chapter reviews the nitrations of aromatic compounds that represent one of the most important classes or organic reactions. However, although a lot of data has been collected in relation to simple substituted benzenes and the reactions have been subjected to quantitative and theoretical studies, the nitration of phenyl heterocycles has been much less studied in a systematic way. There are many methods for effecting the nitration of aromatic compounds. Reactive compounds— for example, phenol—will nitrate in dilute nitric acid, but usually more vigorous reaction conditions consisting of nitric acid (either concentrated or fuming) or nitrate salts in sulfuric acid are used. The cchapter discusses the five-membered ring systems and their benzo derivatives, including pyrroles, benzopvrroles, furans, thiophenes, pyrazoles, indazoles, thiazoles and isothiazoles, and benzimidazoles. The chapter also reviews rings with three and four heteroatoms and fused five-membered ring systems. © 1993, Academic Press Inc. All rights reserved.