Nomenclature of Ethers, Epoxides, and Sulfides

1 Nomenclature of Ethers, Epoxides, and Sulfides 650 Structure and Bonding in Ethers and Epoxides 652 Physical Properties of Ethers 652 

Descriptive Passage and Interpretive Problems 16 Epoxide Rearrangements and the NIH Shift 682 

Intestinal parasites in cattle are controlled by adding monensin to their feed. Monensin belongs to a class of antibiotics known as lonophores ( ion carriers ) that act by forming stable complexes of the kind shown in the space-filling model with metal ions. For more, see the boxed essay Polyether Antibiotics. 

In contrast to alcohols with their rich chemical reactivity, ethers (compounds containing a C—O—C unit) undergo relatively few chemical reactions. As you saw when we discussed Grignard reagents in Chapter 14 and lithium aluminum hydride reductions in Chapter 15, this lack of reactivity of ethers makes them valuable as solvents in a number of synthetically important transformations. In the present chapter you will learn of the conditions in which an ether linkage acts as a functional group, as well as the methods by which ethers are prepared. 

Unlike most ethers, epoxides (compounds in which the C—O—C unit forms a three-membered ring) are very reactive substances. The principles of nucleophilic substitution are important in understanding the preparation and properties of epoxides. 

Ethers are named, in substitutive lUPAC nomenclature, as alkoxy derivatives of alkanes. Functional class lUPAC names of ethers are derived by listing the two alkyl groups in the general structure ROR in alphabetical order as separate words, and then adding the word ether at the end. When both alkyl groups are the same, the prefix di- precedes the name of the alkyl group. 

Substitutive lUPAC name Functionai ciass lUPAC name  

Recall from Section 6.18 that epoxides may be named as -epoxy derivatives of alkanes in substitutive lUPAC nomenclature. 

Sulfides are sometimes informally referred to as thioethers, but this term is not part of systematic lUPAC nomenclature. 

Ethers are described as symmetrical or unsymmetrical depending on whether the two groups bonded to oxygen are the same or different. Unsymmetrical ethers are also called mixed ethers. Diethyl ether is a symmetrical ether ethyl methyl ether is an unsymmetrical ether. 

Substitutive lUPAC name Functional class lUPAC name  

Cyclic ethers have their oxygen as part of a ring—they are heterocyclic compounds (Section 3.15). Several have specific lUPAC names. 

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Introduction to Ethers Nomenclature of Ethers Structure and Properties of Ethers Crown Ethers Preparation of Ethers Reactions of Ethers Nomenclature of Epoxides Preparation of Epoxides Enantioselective Epoxidation Ring-Opening Reactions of Epoxides Thiols and Sulfides... 

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