ETHERS

This article appears in Volume V09, Page 808 of the Encyclopedia Britannica.

Encyclopedia Britannica - Main :: EMS-EUD

ETHERS , in organic

chemistry

, compounds of the general

formula

FORMULA
FORMULA (Lat. diminutive of forma, shape, pattern, &c., especially used of rules of judicial
procedure
- PROCEDURE (Fr. procedure, from Lat. procedere, to go for-ward)
)

ROR', where R, R'=alkyl or aryl groups. They may be regarded as the anhydrides of the

alcohols

, being formed by elimination of one molecule of water from two molecules of the

alcohols

; those in which the two hydrocarbon radicals are similar are known as simple ethers, and those in which they are dissimilar as mixed ethers. They may be prepared by the action of concentrated sulphuric acid on the alcohols, alkyl sulphuric acids being first formed, which yield ethers on

heating

HEATING

with alcohols. The process may be made a continuous one by running a thin stream of alcohol continually into the heated reaction mixture of alcohol and sulphuric acid. Benzene sulphonic acid has been used in place of sulphuric acid (F. Krafft, Ber., 1893, 26, p. 2829). A. W. Williamson (Ann., 1851, 77, p. 38; 1852, 81, p. 77) prepared ether by the action of sodiumethylate on

ethyl

ETHYL

iodide, and showed that all ethers must possess the structural

formula

given above (see also Brit. Assoc. Reports, 185o, p. 65). They may also be prepared by

heating

HEATING

the alkyl halides with silver

oxide

OXIDE

.
The ethers are neutral volatile liquids (the first member, methyl ether, is a gas at

ordinary

ORDINARY (med. Lat. ordinarius, Fr. ordinaire)

temperature). Phosphorus pentachloride converts them into alkyl chlorides, a similar decomposition taking place when they are heated with the haloid acids. Nitric acid and chromic acid oxidize them in such a manner that they yield the same products as the alcohols from which they are derived. With chlorine they yield substitution products.
Methyl ether, (CH3)2O, was first prepared by J. B. Dumas and E. Peligot (Ann. chim. phys., 1835, [2] 58, p. 19) by heating methyl alcohol with sulphuric acid. It is best prepared by heating methyl alcohol and sulphuric acid to 14o C. and leading the evolved gas into sulphuric 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, Ber., 1874, 7, p. 699). It is a pleasant-smelling gas, which burns when ignited, and may be condensed 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 hydrochloric acid gas to form a compound (CH3)2OHC1 (C.

Friedel

FRIEDEL, CHARLES (1832-1899)

, Comptes rendus, 1875, 81, p. 152). Methyl

ethyl

ETHYL

ether, CH3.OC,H5, is prepared from methyl iodide and sodium ethylate, or from ethyl iodide and sodium methylate (A. W. Williamson, Ann., 1852, 81, p. 77). It is a liquid which boils at ro8 C.
For diethyl ether see ETHER, and for methyl phenyl ether (anisole) and ethyl phenyl ether (phenetole) see CARBOLIC ACID.

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