Chapter 29 - Fused-Ring Polycyclic Aromatic Compounds Containing One or More Five-Membered Rings

Abstract

This chapter describes specific hydrocarbons, and their derivatives, in which a five-membered ring is fused to two or more other, usually benzenoid, ring systems. Four main groups of such compounds are studied according to the number of rings contiguous with the cyclopentane ring and the manner in which they are fused. The compounds benzindan, acenapthene, fluorene, and fluoranthene, respectively have three, two, one and zero “free” positions on the cyclopentane ring. Compounds with two five-membered rings, and certain hydrocarbons containing seven-membered rings are also reviewed. The bendinzan group is characterized by hydrocarbons, in which a five-membered ring is fused on one side to an aromatic system. The main source of acenapthene is coal tar, but it can be synthetically produced in the laboratory. Fluorene, biphenylenemethane is a colorless crystalline coaltar hydrocarbon. The biphenyl system, diphenylmethane system, indene system, phenanthraquinone, and fluoranthene are the few sources from which fluorenes are obtained. High acidity of the methylene group (9th position) in fluorene accounts for the formation of metallic derivatives, either directly, or by exchange with other organometallic compounds. Fluoranthene is a colorless hydrocarbon abundantly present in coal tar.