KETONES, in chemistry, organic compounds containing the carbonyl group CO and having the general formula R.CO.R', where R and R' are alkyl or aryl groups (see CHEMISTRY : Or ganic). If the groups R and R' are identical, the ketone is called a simple ketone, of which the best known and simplest example is acetone (q.v.), used in large amounts during the World War as a solvent in the manufacture of the explosive cordite. If the groups R and R' are different, a mixed ketone results, and of this class acetophenone (q.v.), may be cited as a typical representative. It is used as a soporific under the name of "hypnone." The Aliphatic Ketones.—This group of ketones is derived from the fatty acids of the acetic acid series. The lower members are liquids and are lighter than water ; the higher members containing C12 and upwards are solid. (For the initial member of the series see ACETONE.) Methyl ethyl ketone, the simplest of the mixed ketones, occurs in crude wood spirit and is also pre pared by distilling a mixture of calcium acetate and propionate; it is a pungent liquid boiling at 81° C. This ketone is employed in the preparation of dimethylglyoxime, a useful analytical reagent for nickel (q.v.). Pinacolin, or methyl tertiary-butyl ketone, a liquid boiling at io6° C and having a cam phoraceous odour, is produced by the action of dilute sulphuric acid on pinacol (see GLYCOLS), this peculiar rearrangement being known as the "pinacone reaction." Methyl nonyl ketone, (CH2)8.CH3 (m.p. C, b.p. 232° C), is the main constitu ent of oil of rue, which also contains methyl heptyl ketone, CH3.00.(CH2)6.CH3 (m.p. C, b.p., 195° C).
(white leaflets, m.p. 55.5° C), together with some acetone, which is readily removed. (3) The catalytic decomposition of fatty acids over thoria or zirconia at 400° C, or over manganous oxide at 45o° C. Either simple or mixed ketones may be thus prepared. (4) Hydration of homologues of acetylene, prefer ably in presence of sulphuric acid or of mercuric salts, I CH3.CO.C6H5. (5) The interaction of Grig nard reagents (q.v.) and nitriles; e.g., acetonitrile, IN, and magnesium ethyl iodide, give an additive compound, :N.MgI, which on treatment with water yields methyl ethyl ketone. (6) The Friedel and Crafts reaction is ap plicable to ketones containing one or two aromatic radicals, e.g., carbonyl chloride with benzene (2 mol.) gives benzophenone, acetyl chloride with benzene gives acetophenone. This reaction has been extended by J. F. Norris and H. E. Couch (192o) to condensations with open-chain unsaturated compounds. Ethylene and benzoyl chloride in presence of aluminium chloride furnish phenyl vinyl ketone, as a yellow oil.