KETONES (apocopated from acetone, from acct-ic, from Lat. uretuni, vinegar), or AcrroxFs. A large and important class of carbon compounds that arc in many respects similar to the alde hydes. While the aldehydes (q.v.) are character ized by the carbonyl group CO to which one hydrogen atom and some hydrOcarbon radicle arc attached, and while most organic acids are char acterized by the carbonyl group CO to which one hydroxyl group (I ) and some hydrocarbon radicle are attached—the ketones contain a car bonyl group to which tiro hydrocarbon radicles are attached. If 11 stand for any hydrocarbon radicle, like methyl (CII,), or ethyl (CJ1.,). the following formulas represent respectively the structure of any aldehyde. any organic acid, and any ketone: For example: 1 trditmry aldehyde, acetic acid, and acetone ( the simplest ketone) are represented respectively by the following structural formulas: .Test as aldehydes are obtained from primary by oxidation, so are ketones produced by the oxidation of seeondary alcohol,. (See Al.conot.s.) In case the oxidation consists in the removal of two hydrogen atoms from the alcohol molecule. Thus normal propyl alcohol.
yields C11,.C1L.C110 (propio nic aldehyde), while isopropyl alcohol, CIL.
CH yields CH,CO.CII, (acetone). One of the general methods employed for the prep aration of ketones consists in heating the cal cium or barium salts of organic acids. Thus ace tone may be prepared by distilling calcium or barium acetate. (See ACETONE.) From the higher fatty acids ketones may be obtained di rectly by heating the acids with phosphoric an hydride. Thus heptylie acid may be directly de composed, according to the following equation: 2C,H„COOH = C,H„.CO.C.H„d- H,0 Heptyllc acid Like the aldehydes, ketones are capable of com bining with acid sodium sulphite, with hydro cyanic acid, etc., and precisely as in the ease of aldehydes, two chlorine atoms may be readily substituted for the oxygen of the carbonyl group, by the action of phosphorus pentaehloride. Thus acetone may be transformed into di-ehloro-pro pane, according to the following reaction: