The mono-amino derivatives or eurhodines are obtained when the arylmonamines are condensed with orthoamino zo compounds; by condensing quinone dichlorimide or para-nitrosodimethyl aniline with monamines containing a free para position, or by oxidizing ortho-hydroxydiaminodiphenylamines (R.
It crystallizes in monoclinic tables which melt at 148-149° C. Chromic acid oxidizes it to pyrene quinone, C16H802, and pyrenic acid, C15H1806.
When treated with chlorine, pyrocatechol (1.2 or ortho-dioxybenzene) (1) yields a tetrachlor ortho-quinone, which suffers further chlorination to hexachlor-o-diketo-R-hexene (2).
This assumed that all coloured substances were derivatives of orthoor para-quinone (see Quinones), and although at the time of its promotion little practical proof was given, yet the theory found wide acceptance on account of the researches of many other chemists.
Quinone, which is light yellow in colour, is the simplest coloured substance on this theory.
He suggests that the term " quinone " theory be abandoned, and replaced by the Umlagerungs theory, since this term implies some intermolecular rearrangement, and does not connote simply benzenoid compounds as does " quinonoid."
The views as to the question of colour and constitution may be summarized as follows: - (i) The quinone theory (Armstrong, Gomberg, R.
Chem., 9, p. 405; To, p. Chromic acid oxidizes phenanthrene, first to phenanthrene-quinone, and then to diphenic acid, HO 2 C C 6 H 4 C 6 H 4 C02H.
Phenanthrene-quinone, [C 6 H 4] 2 [CO] 21 crystallizes in orange needles which melt at 198° C. It possesses the characteristic properties of a diketone, forming crystalline derivatives with sodium bisulphite and a dioxime with hydroxylamine.
Chromic acid oxidizes it to retene quinone, phthalic acid and acetic acid.
It behaves more as a ketone than as a quinone, since with hydroxylamine it yields an oxime, and on reduction with zinc dust and caustic soda it yields a secondary alcohol, whilst it cannot be reduced by means of sulphurous acid.
Soc. chim., 18 94 (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: C 6 H 5 OH+H 2 N C 6 H 4 N (CH 3) 2 - *O:C 6 H 4 :N C 6 H 4 N(CH 3) 2; these compounds yield the quinone when heated with mineral acids.
OH, which can further yield quinone dioximes, HON:C 6 H 4 :NOH.
Benzoquinone (para) or ordinary quinone, C 6 H 4 0 2, is formed by the oxidation of aniline with sodium bichromate and sulphuric acid.
Fittig (Ann., 1876, 180, p. 23) readily explains the formation of the monoand di-oximes of quinone and also that it readily combines with bromine.
Quinone-chlorimide, C1N : C 6 H 4: 0, is obtained when paraaminophenol is oxidized with bleaching powder.
Quinone-dioxime, HON: C 6 H 4: 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, C 6 H40 2 -C 6 H 4 (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.
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 C6H202.OH.
Willstatter (Ber., 1904, 37, p. 4744), by dissolving pyrocatechin in absolute ether containing ignited sodium sulphate and then adding dry silver oxide, obtained the quinone in dark red crystalline plates which decompose between 60° and 70° C.
For naphthalene quinones see Naphthalene; for anthracene quinone see Anthraquinone; and for phenanthrene quinone see Phena Nt H Rene.
As being quinone hydrazones, type R NH N: R l: 0.
Chem., 1896, 21, p. 355; Ber., 1900, 33, p. 1302)examined the questionfromthe physico-chemical standpoint by determining the freezing-point depressions, the result being that the para-oxyazo compounds give abnormal depressions and the ortho-oxyazo compounds give normal depressions; Auwers then concluded that the para compounds are phenolic and the ortho compounds are quinone hydrazones or act as such.
Hantzsch (Ber., 18 99, 3 2, pp. 59 o, 3089) considers that the oxyazo compounds are to be classed as pseudoacids, possessing in the free condition the configuration of quinone hydrazones, their salts, however, being of the normal phenolic type.
Soc., 1900, 77, pp. 99 et seq.) nitrated para-oxyazobenzene with dilute nitric acid and found that it gave a benzene-azo-ortho-nitrophenol, whereas quinone are not attacked by dilute nitric acid.
The so-called chrysophanic acid found in Xanthoria (Physcia) parietina is not an acid but a quinone and is better termed physcion.
Chromic acid in glacial acetic acid solution oxidizes it to picene-quinone, picene-quinone carboxylic acid, and finally to phthalic acid.
On oxidation .ith chromic acid it forms a quinone, C 15 H 8 0 2, and an a-diphenylene keto carboxylic acid C E I-4 3.
Para-dinitrobenzene results from the action of nitrogen peroxide on an ethereal solution of quinone dioxime (R.
, 27, p. 39 2), crystallizes in colourless prisms which melt at 234° C. When heated in vacuo to 240° C. it yields hydroquinone, quinone and pyrogallol.