Ether

ETHER, in chemistry, any member of a certain class of sub stances (of which the well known anaesthetic, di-ethyl ether, commonly called "ether" or "aether," is one) composed of carbon, hydrogen and oxygen, and having the general formula, R.O.R', where R•R' = alkyl or aryl groups (see CHEMISTRY : Organic) .

The term ether formerly included the esters (q.v.) of organic acids, such as acetic ether, now termed ethyl acetate. The true ethers are formed by elimination of one molecule of water from two molecules of the alcohols; the two hydrocarbon radicals are similar in simple ethers, and dissimilar in mixed ethers. They may be prepared by the action of concentrated sulphuric acid on the alcohols; alkyl sulphuric acids are first formed, and yield ethers on being heated with alcohols. The process is rendered con tinuous by running an alcohol slowly into the heated reaction mix ture of alcohol and sulphuric acid. Benzenesulphonic acid has been used in place of sulphuric acid (F. Krafft, 1893). A. W. William son explained the mechanism of this action in 1850; in 1851 and 1852 he prepared di-ethyl ether (v. below) by the action of sodium ethoxide on ethyl iodide, and showed that all ethers possess the structural formula given above. They may also be prepared by heating the alkyl halides with silver oxide. Phosphorus pentachlo ride or halogen hydrides convert them into alkyl chlorides. With chlorine they yield substitution products.

Di-methyl ether,

first obtained by J. B. Dumas and E. Peligot, 1835, is best prepared by heating methyl alcohol and sulphuric acid to 540° C and leading the evolved gas into sul phuric acid. The sulphuric acid solution is then allowed to drop slowly into an equal volume of water, when the methyl ether is liberated (E. Erlenmeyer and A. Kriechbaumer, 1874). It is a pleasant-smelling inflammable gas, condensing to a liquid which boils at —23.6° C. It is somewhat soluble in water and readily soluble in alcohol and concentrated sulphuric acid. It combines with hydrogen chloride to form a compound Methyl ethyl ether, prepared from methyl iodide and sodium ethoxide, or from ethyl iodide and sodium methoxide, is a liquid boiling at 1o.8° C. The homologous ethers are also liquids, with boiling points rising with increase of carbon content.

Di-ethyl ether,

(C2H5)20, the ether of pharmacy is a colour less, volatile, highly inflammable liquid, of specific gravity 0.736 at o°, boiling-point 35° C, and freezing-point —117.4° C, with a pow erful characteristic odour, and a hot sweetish taste; it is soluble in ten parts of water, and in all proportions in alcohol ; it dissolves bromine, iodine, and, in small quantities, sulphur and phosphorus, also the volatile oils, most fatty and resinous substances, guncot ton, caoutchouc and certain vegetable alkaloids. A mixture of the vapour with oxygen or air is violently explosive. The making of ether by the action of sulphuric acid on alcohol was known in about the 13th century; and later Basil Valentine and Valerius Cordus described its preparation and properties. The name ether appears to have been applied to the drug only since the times of Frobenius, who in 1730 termed it spiritus aethereus or vini vitrio latus. It was considered to be a sulphur compound, hence its name sulphuric ether; this idea was proved to be erroneous by Valentine Rose in about 1800. Ether is manufactured by the dis tillation of 5 parts of 90% alcohol with 9 parts of concentrated sulphuric acid at a temperature of C, a constant stream of alcohol being caused to flow into the mixture during the operation. The distillate is purified by treatment with lime and calcium chloride, and subsequent distillation.

The presence of so small a quantity as 1% of alcohol may be detected in ether by the colour imparted to it by aniline violet ; if water or acetic acid be present, the ether must first be shaken with anhydrous potassium carbonate. Chromic acid oxidizes ether to acetic acid and ozone oxidizes it to ethyl peroxide. Ethyl peroxide also forms spontaneously in ether under many conditions of storage. This action is inhibited by certain metals, notably copper. In contact with hydrogen iodide at o° C, it forms ethyl iodide, and with water and a little sulphuric acid at 180° C, it yields alcohol. It forms crystalline compounds with bromine and with many metallic salts.

Ether may be transported in iron drums, glass bottles and tin cans. Its principal use is in the manufacture of smokeless powder, organic synthesis as a solvent in analytical chemistry and for medicinal purposes. (See below.) No flames or sparking electrical equipment may be used in connection with the industrial applica tion of ether.

Medicinal Uses.—(See ANAESTHESIA.) Applied externally, ether evaporates rapidly, producing such intense cold as to cause marked local anaesthesia. It is best applied as a fine spray, but ethyl chloride (q.v.) is generally found more efficient and produces less subsequent discomfort. Ether aids the absorption of fats and may be used with cod liver oil when the latter is administered by the skin. Ether, when subcutaneously injected, is perhaps the most rapid and powerful cardiac stimulant known, and is often em ployed for this purpose in cases of syncope under anaesthesia. Taken internally, ether acts in many respects similarly to alcohol and chloroform, but its stimulant action on the heart is much more marked owing to its rapid diffusion.

Chronic Poisoning.—A little more than a teaspoonful will pro duce a condition of inebriation, but the dose must soon be in creased. The principal symptoms of chronic ether-drinking are a weakening of the activity of the special senses, and notably sight and hearing, a lowering of the intelligence and a partial paralysis of motion. The whole moral tone of the addict is lowered and he neglects his personal appearance. The effect is similar to chronic alcoholism in an advanced stage but the deterioration is more rapid and more marked.