ETHERS. An important class of carbon com pounds related to the alcohols (q.v.). Their re lation to the alcohols is analogous to the relation of the metallic oxides (like to the metallic hydroxides (like KOH). Thus, while the com position of ordinary ether (the liquid used for ana•stliesia during surgical operations) is repre sented by the formula the composition of ordinary alcohol is C,I1,0H. While, therefore, an alcohol may be defined as a hydroxide of a hydrocarbon radiele (like methyl. CH„ or ethyl, an ether may be defined as an oxide of such radicles. The close relationship existing between ethers and alcohols is shown by the readiness with which the former may be pre pared from the latter. Thus ordinary ether is usually made by the action of sulphuric acid upon alcohol. (See ETHER.) Another method by which ethers may be prepared is very in genious and serves to demonstrate clearly their chemical constitution. lt consists in treating a halogen derivative of a hydrocarbon, such as ethyl chloride, ethyl bromide, or ethyl iodide, with the sodium compound of an alcohol. Ethyl iodide is represented by the formula so dium alcoholate, by the formula Since sodium (Na) has a great affinity for iodine (1), the iodide and the alcoholate will, on being mixed, readily enter into chemical reaction, by virtue of which a transformation will take place that can be represented only by the following chemical equation: = NaI + Ethyl Iodide Sodium Sodium Di-ethyl ether alcoholate Iodide Ethers arc usually subdivided into simple and mixed. The two hydrocarbon radicles in a sim
ple ether are identical; in a mixed ether they are different. Thus ordinary ether is a simple ether, its formula being On the con trary, methyl-ethyl ether, represented by the formula is a mixed ether. Mixed ethers may be prepared by the same methods as simple ethers. Thus methyl-ethyl ether may be obtained either by treating a mixture of methyl alcohol (wood alcohol) and ordinary (ethyl) alcohol with sulphuric acid, or by treating so dium methylate with ethyl iodide (CAI). By the latter method the formation of the mixed ether would take place according to the following chemical equation: = NaI Sodium Ethyl iodide Sodium Methyl-ethyl methylate Iodide ether The ethers are as a rule very stable compounds that are not affected either by alkalies or by di lute acids. Most of them are light, volatile, in flammable liquids, insoluble in water, but readily soluble in the alcohols. The most typical and useful compound of the class is ordinary ether. The chemical constitution of the ethers was first clearly explained by Williamson in 1855.
The term compound ethers is sometimes applied to another class of compounds, which are. how ever, at present usually termed esters, or ethereal salts. See ESTERS.