The more complex phenazines, such as the naphthophenazines, naphthazines and naphthotolazines, may be prepared by condensing ortho-diamines with ortho-quinones (0.
Certain a-diketones condense to form benzenoid quinones, two molecules of the diketone taking part in the reaction; thus diacetyl, CH 3 CO CO CH 3, yields p-xyloquinone, C 6 H 2 (CH 3) 2 0 2 (Ber., 1888, 21, p. 1411), and acetylpropionyl, CH 3 CO CO C 2 H 5, yields duroquinone, or tetramethylquinone, C 6 (CH 3) 4 0 2, Oxymethylene compounds, characterized by the grouping > C:CH(OH), also give benzene derivatives by hydrolytic condensation between three molecules; thus oxymethylene acetone, or formyl acetone, CH 3 CO.
Aminoand oxy-benzenes, aminophenols, quinones, and oxycarboxylic acids.
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.
When treated with hydrochloric acid and potassium chlorate, no chlorinated quinones are obtained (M.
QUINONES, in organic chemistry, a group of compounds in which two hydrogen atoms of a benzene nucleus are replaced by two oxygen atoms. This replacement may take place either in the ortho or para positions, giving rise to orthoquinones or to paraquinones; metaquinones do not appear to have been isolated.
The para or true quinones are obtained by the oxidation of hydrocarbons with chromic acid or of various para di-derivatives of benzene with chromic acid mixture, such, for example, as para-aminophenol, para-phenylene diamine, paraa.minoazobenzene, &c. H.
For naphthalene quinones see Naphthalene; for anthracene quinone see Anthraquinone; and for phenanthrene quinone see Phena Nt H Rene.