Online Encyclopedia

RCN

Online Encyclopedia
Originally appearing in Volume V15, Page 762 of the 1911 Encyclopedia Britannica.
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RCN + R'MgI - RR'C:N•Mgl R•CO•R'+ NH3+MgLOH. The ketones are of neutral reaction, the lower members of the series being colourless, volatile, pleasant-smelling liquids. They do not reduce silver solutions, and are not so readily oxidized as the aldehydes. On oxidation, the molecule is split at the carbonyl group and a mixture of acids is obtained. Sodium amalgam reduces them to secondary alcohols; phosphorus pentachloride replaces the carbonyl oxygen by chlorine, forming the ketone chlorides. Only those ketones which contain a methyl group are capable of forming crystalline addition compounds with the alkaline bisulphites (F. Grimm, Ann., 1871, 157, p. 262). They combine with hydrocyanic acid to form nitriles, which on hydrolysis furnish hydroxyacids, (CH3)2CO --> (CH3)2C•OH•CN -> (CH3)2•C•OH•CO2H; with phenylhydrazine they yield hydrazones; with hydrazine they yield in addition ketazines RR'•C:N•N:C•RR' (T. Curtius), and with hydroxylamine ketoximes. The latter readily under-go the " Beckmann " transformation on treatment with acid chlorides, yielding substituted acid amides, RR'.C:NOH --> RC(NR')•OH •-~ R.CO.NHR' (see OxIMES, also A. Hantzsch, Ber.,1891,24, p. 13). The ketones react with mercaptan to form mercaptols (E. Baumann, Ber., 1885, 18, p. 883), and with concentrated nitric acid they yield dinitroparaffins (G. Chancel, Bull. de la soc. chim., 1879, 31, p. 503). With nitrous acid (obtained from amyl nitrite and gaseous hydrochloric acid, the ketone being dissolved in acetic acid) they form isonitroso-ketones, R•CO•CH:NOH (L. Claisen, Ber., 1887, 20, pp. 656, 2194). With ammonia they yield complex condensation products; acetone forming di- and tri- acetonamines (W. Heintz, Ann. 1875, 178, p. 305; 1877, 189, p. 214. They also condense with aldehydes, under the influence of alkalis or sodium ethylate (L. Claisen, Ann., 1883, 218, pp. 121, 129, 145; 1884, 223, p. 137; S. Kostanecki and G. Rossbach, Ber., 1896, 29, pp. 1488, 1495, 1893, &c.). On treatment with the Grignard reagent, in absolute ether solution, they yield addition products which are decomposed by water with production of tertiary alcohols (V. Grignard, Comptes rendus, 1900, 130, p. 1322 et seq.), RR'CO-3 RR'•C(OMgI)•R"-) RR'R"•C(OH) + MgLOH. Ketones do not polymerize in the same way as aldehydes, but under the influence of acids and bases yield condensation products; thus acetone gives mesityl oxide, phorone and mesitylene (see below). _ For dimethyl ketone or acetone, see ACETONE. Diethyl ketone, (C2H6)2•CO, is a pleasant-smelling liquid boiling at 102.7° C. With concentrated nitric acid it forms dinitroethane, and it is oxidized by chromic acid to acetic and propionic acids. Methylnonylketone, CH3•CO•C9H19, is the chief constituent of oil of rue, which also contains methylheptylketone, CH3•CO•C7 H15, a liquid of boiling-point 85-90° C. (7 mm.), which yields normal caprylic acid on oxidation with hypobromites. Mesatyl oxide, (CH3)2C:CH•CO•CH3, is an aromatic smelling liquid of boiling point 129.5-130° C. It is insoluble in water, but readily dissolves in alcohol. On heating with dilute sulphuric acid it yields acetone, but with the concentrated acid it gives mesitylene, C9Hi2-Potassium permanganate oxidizes it to acetic acid and hydroxyisobutyric acid (A. Pinner, Ber., 1882, 15, p. 591). It forms hydroxyhydrocollidine when heated with acetamide and anhydrous zinc chloride (F. Canzoneri and G. Spica, Gam chim. Ital., 1884, 14, P•349)• Phorone,(CH3)2C:CH•CO•CH:C(CH3)2,formsyellow crystals which melt at 28° C. and boil at 197.2° C. When heated with phosphorus pentoxide it yields acetone, water and some pseudocumene. Dilute nitric acid oxidizes it to acetic and oxalic acids, while potassium permanganate oxidizes it to acetone, carbon dioxide and oxalic acid.
End of Article: RCN
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RC (:N•OH)R'-RC(OH)
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RDTALIDACEAE

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