CH3  .CO-CO•CH3 CH3•C-CO-CH E CH3•CO•CO•CH3 HC-CO•C-CH3; whilst P . H . Bayrac (

Bull. sac. chim., 1894 (3) 11, p . 1129) obtained anilino-derivatives of the paraquinones by the action of an aqueous solution of potassium chromate on an acetic acid solution of para-aminodimethylaniline and phenol: C6H60H+H2N•C6H4•N (CH3)2->O:C6H4:N.C6H4•N(CH3)2; these compounds yield the quinone when heated with mineral acids . The paraquinones are generally crystalline solids of a yellowish colour, having a characteristic sharp odour and being volatile in steam . They are readily reduced to the corresponding hydroquinones or para-dihydroxy-benzenes, and also combine with hydroxylamine hydrochloride to form nitrosophenols, ON•C6H4.OH, which can further yield quinone dioximes, HON:CsH4:NOH . Paraquinones also combine with ammonia and with amines yielding amino-derivatives and hydroquinones . The orthoquinones more resemble the a-diketones; they are crystalline solids of a red or yellow colour, but differ from the paraquinones in being devoid of smell and not volatile in a current of steam . Benzoquinone (para) or ordinary quinone, C6H402, is formed by the oxidation of aniline with sodium bichromate and sulphuric acid . It sublimes in 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 bromine .

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 molecule a peroxide configuration which accounts for its oxidizing powers but not for the fact that each oxygen atom is capable of replacement by one atom of chlorine . The second formula, due to R . Fittig (Ann., 1876, 18o, p . 23) readily explains the formation of the mono- and di-oximes of quinone and also that it readily combines with bromine . Quinone-chiorimide, C1N : C6H4 : 0, is obtained when paraaminophenol is oxidized with bleaching 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

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 cold concentrated nitric acid oxidizes it to para-dinitrobenzene . Quinhydrone, C6H402•C6H4(OH)2, is formed by the direct union of quinone and hydroquinone or by careful oxidation of hydroquinone with ferric chloride solution . On boiling with water it decomposes into quinone and hydroquinone . Benzoquinone (ortho).—C . L . Jackson (Amer . Chem . Jour., 1901, 26, p. to) attempted to prepare this compound by the action of iodine on the lead salt of pyrocatechin suspended in chloroform . A deep red solution was obtained but the free quinone was not isolated since the solution on standing deposits nearly black crystals of dihydroxyphenylhydroxybenzoquinone (HO)2C6H3•C6H2O2.OH . R .

Willstatter (Ber., 1904, 37, p . 4744), by dissolving pyrocatechin

QUINTAIN in absolute ether containing ignited sodium sulphate and then adding dry silver oxide, obtained the quinone in dark red crystalline plates which decompose between 6o° and 7o° C . For naphthalene quinones see NAPHTHALENE; for anthracene quinone see ANTHRAQUINONE; and for phenanthrene quinone see PHENA NT H RENE . Quinoles.—The quinoles are a series of compounds of the type HoR >(=-- --\–/-O,obtained by the oxidation of para-alkylated phenols with nitric acid, Caro's acid or bromine (Auwers, Ber., 1897–1903; E . 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 character . QUINO%ALINES (Benzopyrazines), in organic chemistry, heterocyclic compounds containing a ring complex made up of a benzene ring and a pyrazine ring (formula I.); they are isomeric with the cinnolenes, phthalazines and quinazolines .

They are formed by the condensing ortho-diamines with 1.2 diketones (Hinsberg, Ann., 1887, 237, p . 327), the

parent substance of the group (quinoxaline) resulting when glyoxal is so condensed, whilst substitution derivatives arise when a-ketonic acids, a-chlorketones, a-aldehyde alcohols and a-ketone alcohols are used in place of diketones .