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CH3 .CO-CO•CH3 CH3•C-CO-CH E CH3•CO•CO•CH3 HC-CO•C-CH3; whilst P. H. Bayrac (See also:Bull. See also:sac. chim., 1894 (3) 11, p. 1129) obtained anilino-derivatives of the paraquinones by the See also:action of an aqueous See also:solution of See also:potassium chromate on an acetic See also:acid solution of See also:para-aminodimethylaniline and phenol: C6H60H+H2N•C6H4•N (CH3)2->O:See also:C6H4:N.C6H4•N(CH3)2; these compounds yield the quinone when heated with See also:mineral acids. The paraquinones are generally crystalline solids of a yellowish See also:colour, having a characteristic See also:sharp odour and being volatile in See also:steam. They are readily reduced to the corresponding hydroquinones or para-dihydroxy-benzenes, and also combine with See also:hydroxylamine hydrochloride to See also:form nitrosophenols, ON•C6H4.OH, which can further yield quinone dioximes, HON:CsH4:NOH. Paraquinones also combine with See also:ammonia and with See also:amines yielding amino-derivatives and hydroquinones. The orthoquinones more resemble the a-See also:diketones; they are crystalline solids of a red or yellow colour, but differ from the paraquinones in being devoid of See also:smell and not volatile in a current of steam. Benzoquinone (para) or See also:ordinary quinone, C6H402, is formed by the oxidation of See also:aniline with See also:sodium bichromate and sulphuric acid. It sublimes in See also:golden yellow needles. Hot concentrated nitric acid oxidizes it to picric acid and oxalic acid, whilst on treatment with hydrochloric acid and potassium chlorate it yields chloranil (tetrachloroquinone). It combines directly with two and four atoms of See also:bromine. See also:Free hydroxylamine reduces it to hydroquinone. It combines directly with aniline to form dianilidoquinone, dianilidoquinone-anil and dianilidoquinone-dianil or azophenine. Two alternative structural formulae have been given to benzoquinone, namely: ~O O and 0=~>O The former, due to C. Graebe (Zeit. f. Chemie, 1867, 3, p. 39), ascribes to the See also:molecule a peroxide configuration which accounts for its oxidizing See also:powers but not for the fact that each See also:oxygen See also:atom is capable of replacement by one atom of See also:chlorine. The second See also:formula, due to R. See also:Fittig (See also:Ann., 1876, 18o, p. 23) readily explains the formation of the mono- and di-See also:oximes of quinone and also that it readily combines with bromine. Quinone-chiorimide, C1N : C6H4 : 0, is obtained when paraaminophenol is oxidized with See also:bleaching See also:powder. It is a yellow crystalline solid readily volatile in steam. The dichlorimide, CIN : C6H4 : NCI, is formed in a similar manner from paraphenylene diamine. It is a strong oxidizing See also:agent. Quinone-dioxime, HON : C6H4 : NOH, crystallizes in colourless or yellow needles, which decompose when heated to about 240° C. Potassium ferrocyanide in alkaline solution oxidizes it to dinitrosobenzene, whilst See also:cold concentrated nitric acid oxidizes it to para-dinitrobenzene. Quinhydrone, C6H402•C6H4(OH)2, is formed by the See also:direct See also:union of quinone and hydroquinone or by careful oxidation of hydroquinone with ferric chloride solution. On boiling with See also:water it decomposes into quinone and hydroquinone. Benzoquinone (ortho).—C. L. See also:Jackson (Amer. Chem. Jour., 1901, 26, p. to) attempted to prepare this See also:compound by the action of See also:iodine on the See also:lead See also:salt of See also:pyrocatechin suspended in See also:chloroform. A deep red solution was obtained but the free quinone was not isolated since the solution on See also:standing deposits nearly See also:black crystals of dihydroxyphenylhydroxybenzoquinone (HO)2C6H3•C6H2O2.OH. R. Willstatter (Ber., 1904, 37, p. 4744), by dissolving pyrocatechin See also:QUINTAIN in See also:absolute See also:ether containing ignited sodium sulphate and then adding dry See also:silver See also:oxide, obtained the quinone in dark red crystalline plates which decompose between 6o° and 7o° C. For See also:naphthalene See also:quinones see NAPHTHALENE; for See also:anthracene quinone see See also:ANTHRAQUINONE; and for phenanthrene quinone see PHENA NT H RENE. Quinoles.—The quinoles are a See also:series of compounds of the type See also:HoR >(=-- --\–/-O,obtained by the oxidation of para-alkylated phenols with nitric acid, See also:Caro's acid or bromine (Auwers, Ber., 1897–1903; E. See also:Bamberger, ib., 1903, 36, p. 2028; Th. Zincke, ib., 1895, 28, p. 3121); by the action of sulphuric acid on para-substituted phenylhydroxylamines (E. Bamberger), and by the action of the Grignard reagent on quinones (Bamberger). They are crystalline solids which are readily converted into para-alkylated phenols by reducing agents. They possess a weak acid and also an alcoholic See also:character. QUINO%ALINES (Benzopyrazines), in organic See also:chemistry, heterocyclic compounds containing a See also:ring complex made up of a See also:benzene ring and a pyrazine ring (formula I.); they are isomeric with the cinnolenes, See also:phthalazines and See also:quinazolines. They are formed by the condensing ortho-diamines with 1.2 diketones (Hinsberg, Ann., 1887, 237, p. 327), the See also:parent substance of the See also:group (quinoxaline) resulting when glyoxal is so condensed, whilst substitution derivatives arise when a-ketonic acids, a-chlorketones, a-aldehyde See also:alcohols and a-ketone alcohols are used in See also:place of diketones. Additional information and CommentsThere are no comments yet for this article.
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