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.
Soc., 1906, 89, p. 1787) have disputed the correctness of this explanation, and the latter has prepared melliteins and pyromelliteins, which are highly-coloured compounds produced from mellitic and pyromellitic acids, and which cannot be formulated as quinones.
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.
Bamberger), and by the action of the Grignard reagent on quinones (Bamberger).
It is readily soluble in water, melts at 193° C., and is decomposed at a higher temperature into chromium sesquioxide and oxygen; it is a very powerful oxidizing agent, acting violently on alcohol, converting it into acetaldehyde, and in glacial acetic acid solution converting naphthalene and anthracene into the corresponding quinones.
Examples of novel natural products from higher plants are given and include alkaloids, terpenoids, phenolics and quinones.
Hausen BM (1978) Sensitizing capacity of naturally occurring quinones.
Several potentially allergenic quinones are also present in the wood (Sandermann et al.
18, p. 499) in 1885, who showed that it yielded hexaoxybenzene, C 6 (OH) 6, when acted upon with dilute hydrochloric acid further investigation of this compound brought to light a considerable number of highly interesting derivatives (see Quinones).
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.
It is readily soluble in water, melts at 193Ã‚° C., and is decomposed at a higher temperature into chromium sesquioxide and oxygen; it is a very powerful oxidizing agent, acting violently on alcohol, converting it into acetaldehyde, and in glacial acetic acid solution converting naphthalene and anthracene into the corresponding quinones.
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