Ethers epoxides

For the most part, cyclic ethers hehave like acyclic ethers. The chemistry of the ether functional group is the same, whether it s in an open chain or in a ring. Common cyclic ethers such as tetrahydrofuran and dioxane, for example, are often used as solvents because of their inertness, yet they can be cleaved by strong acids. 

The one group of cyclic ethers that behaves differently from open-chain ethers are the three-membered-ring compounds called epoxides, or oxiranes, which we saw in Section 8.7. The strain of the three-membered ring gives epoxides unique chemical reactivity. 

Ethylene oxide, the simplest epoxide, is an intermediate in the manufacture of both ethylene glycol, used for automobile antifreeze, and polyester polymers. Approximately 18 million metric tons of ethylene oxide is produced worldwide each year, most of it by air oxidation of ethylene over a silver oxide catalyst at 300 °C. This process is not useful for other epoxides, however, and is of little value in the laboratory. 

Note that the name ethylene oxide is not a systematic one because the -ene ending implies the presence of a double bond in the molecule. The name is frequently used, however, because ethylene oxide is derived from ethylene by addition of an oxygen atom. Other simple epoxides are named similarly. The systematic name for ethylene oxide is 1,2-epoxyethane. 

In the laboratory, as we saw in Section 8.7, epoxides are usually prepared by treatment of an alkene with a peroxyacid (RCO3H), typically m-chloroperoxy-benzoic acid. 

---

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

The most striking chemical property of epoxides is their far greater reactivity toward nude ophilic reagents compared with that of simple ethers Epoxides react rapidly with nude ophiles under conditions in which other ethers are inert This enhanced reactivity results from the angle strain of epoxides Reactions that open the nng relieve this strain... 

Carey Organic Chemistry I 16 Ethers Epoxides and I Text Fifth Edition Sulfides... 

Because di-/ fZ-alkyl peroxides are less susceptible to radical-induced decompositions, they are safer and more efficient radical generators than primary or secondary dialkyl peroxides. They are the preferred dialkyl peroxides for generating free radicals for commercial appHcations. Without reactive substrates present, di-/ fZ-alkyl peroxides decompose to generate alcohols, ketones, hydrocarbons, and minor amounts of ethers, epoxides, and carbon monoxide. Photolysis of di-/ fZ-butyl peroxide generates / fZ-butoxy radicals at low temperatures (75), whereas thermolysis at high temperatures generates methyl radicals by P-scission (44). 

Non-glycidyl ether epoxides Diluents, Rexibilisers tmd other Additives Structure and Properties of Cured Resins Applications... 

Production and Uses of Aliphatic Compounds II Ether, Epoxide and Pnlyeiher, Carboxylic Acids and Their Denvatives, Sulfonic Acids, Toxicological Data of Aliphatic Fluorine Compounds (Ger) Liebig, H, Ulm, K Chem Ztg 100 3-14 270... 

---