Ethers

Abstract

Naturally occurring ethers may be constituents of essential oils and may be extracted from these sources. Although some ethers may appear naturally, they may be prepared synthetically from other chemicals or other ethers. Symmetrical ethers are produced by the catalytic dehydration of their corresponding alcohols, for example, diethyl ether from ethanol. They are also obtained as by‐products from the formation of their corresponding esters or alcohols. Ethers may also be made by special synthesis procedures. Some ethers are obtained through the destructive distillation of selected hardwoods. Ethers have a wide variety of industrial uses. Their commercial value is recognized in the following industries: rubber, plastics, paints and coatings, refrigeration, medicine, dentistry, petroleum, chemical, perfume, cosmetics, toiletries, and food. The more volatile ethers have been used as liquid refrigerants, general anesthetics, commercial solvents, primers for gasoline engines, fuel additives, and rocket propellants. Other ethers have been used as alkylating agents in chemical syntheses of organic chemicals and in the manufacture of polymers. They are also used to denature alcohol. Halogenated ethers are used in the preparation of ion‐exchange resin, which is a modified polystyrene resin that is chloromethylated and then treated with a tertiary amine or with a polyamine. Ethers have wide use as commercial solvents and extractants for esters, gums, hydrocarbons, alkaloids, oils, resins, dyes, plastics, lacquers, and paints. They are used as dewaxing extractants for lubricating oils. Ethers have had limited use as cleaning and spotting agents. They are used as chemical intermediates in the manufacture of textile aids, such as dyes and resins. In the pharmaceutical industry, ethers are used as solvents, suspending agents, flavorings for oral drugs, and dental products. They are used to increase viscosity, as penetrants and wetting agents and as antioxidants and stabilizers. Ethers are used in foods as flavorings and in perfumes as fragrances. They are used as solvents for elastomers and for regenerating rubber. They have use as antiskinning agents in surface coatings and as weathering agents for paints and plastics. Ethers are also used in soaps. Ethers appear in heat transfer agents. Several industries use specific ethers for thickening, dispersing, suspending, binding, and film forming. The data presented here are arranged according to the chemical structure of the compounds. An effort has been made to place the chemicals within each group in an order that represents an increase in chain length. Even though the number of chemicals in any one group is limited, it is possible to make general, comparative statements. This corresponds with the acute toxicity data available in the NIOSH Registry of Toxic Effects of Chemical Substances . The oral toxicity and concentrated vapor data indicate that as the chain length increases in the symmetrical ethers, the toxicity is reduced. The inverse is true for skin penetration toxicity.