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Ebook Organic chemistry (10th edition): Part 2

(BQ) Part 2 book "Organic chemistry" has contents: Radical reactions, alcohols and ethers synthesis and reactions; alcohols from carbonyl compounds oxidation–reduction and organometallic compounds; conjugated unsaturated systems, aromatic compounds. and other contents. | solom_c10_459-501hr.qxd 28-09-2009 15:09 Page 459 Radical Reactions 10 Unpaired electrons lead to many burning questions about radical types of reactivity. In fact, species with unpaired electrons are called radicals, and they are involved in the chemistry of burning, aging, disease, as well as in reactions related to destruction of the ozone layer and the synthesis of products that enhance our everyday lives. For example, polyethylene, which can have a molecular weight from the thousands to the millions, and practical uses ranging from plastic films and wraps to water bottles, bulletproof vests, and hip and knee replacements, is made by a reaction involving radicals. Oxygen that we breathe and nitric oxide that serves as a chemical signaling agent for some fundamental biological processes are both molecules with unpaired electrons. Highly colored natural compounds like those found in blueberries and carrots react with radicals and may protect us from undesirable biological radical reactions. Large portions of the economy hinge on radicals, as well, from reactions used to make polymers like polyethylene, to the target action of pharmaceuticals like Cialis, Levitra, and Viagra, which act on a nitric oxide biological signaling pathway. Reactions with radicals also play a role in organic synthesis. In this chapter we study the properties and reactivity of species with unpaired electrons, and we shall find that they are radically important to chemistry and life. 459 Openmirrors.com solom_c10_459-501hr.qxd 28-09-2009 460 15:09 Page 460 Chapter 10 Radical Reactions 10.1 Introduction: How Radicals Form and How They React So far almost all of the reactions whose mechanisms we have studied have been ionic reactions. Ionic reactions are those in which covalent bonds break heterolytically and in which ions are involved as reactants, intermediates, or products. Another broad category of reactions has mechanisms that involve homolysis of covalent bonds with the .