A Manual of the Chemistry of the Carbon Compounds

436 THE CHEMISTRY OF
trioxide in the same solveut. It readily sublimes in bright-yellow
crystals, melting at 125°, and is volatile in the vapour of water
at 100°, communicating to it a pungent odour, resembling that of
ordinary quinone.
Naphtlwhydroqiiinone Cl((Ho(OH)2 is prepared by boiling the quinone
with strong hydriodic acid and amorphous phosphorus; on cooling,
the hydroquinone is deposited in long colourless needles, melting at
176°. Oxidizing agents reconvert it into the quinone. It differs
from the isomene dioxynaphthalene by being more readily soluble in
water.
Naphihoquinhydrone C,0H8-| Q o C^* OH 1 8 body is obtained
""
by boiling an aqueous solution of napthonydroquinone with naphthoquinone,
or by boiling the latter with weak hydriodic acid, and
amorphous phosphorus; it forms dark-purple crystals.
DidUorompMlwquinone C8H4CLj0£ is produced by the action of
potassium chlorate and hydrochloric acid ou a dinitronaphthoL It
crystallizes from hot alcohol in yellow needles.
DickloronaplUlwhydroquinone C0H4CL(OHL is obtained by boiling
the preceding compounds with hydriodic acid and phosphorus, and
crystallizes in colourless prisms.
Oxyeliloronaphtlioquinone, or Chtoi-oxynapMlvalic Acid Cj0H4(OH)
CIO;, is formed by treating chloronaphthalens dichloride with nitric
acid ; it forms yellow crystals, melting above 20(1°, and forms salts
having a yellow or red colour. By dissolving dichloronaphthoquinone
in hot soda-solution a crimson liquid is obtained, containing the
sodium-salt :—
C10H4C1203 + 2NaOH = C10H4(ONa)ClOs + NaCl + HaO
Dioxynaphtlwquinane, or Naplithazarin C,0H4(OH)8O!j.—This compound
is prepared by heating sulphuric acid to 200°, and adding onetenth
of its weight of a dinitronaphthalene, and then gradually zinc.
After cooling the solution is diluted with 10 parts of water, boiled
and filtered. The gelatinous moss which separates out on cooling is
crystallized from alcohol, and thus the compound is obtained in brown
needles having a green lustre, On heating it sublimes in feathery
tufts with a brilliant beetle-green reflection. In alfealis it dissolves
with a beautiful blue colour; this solution yields blue precipitates
with the salts of barium, calcium, and lead; alum produces a red lake
and feme salts a bluish-grey precipitate. Red-hot zinc-dust reduces
it to naphthalene, and when sodium-amalgam is added to its aqueous
solution it becomes colourless, showing that this body is a quinone,
whilst its metallic compounds prove that it is also a phenol.
ifapMhylpmpnrie Acid C^H^Sfi^.—By acting with potassium
cyanide on an alcoholic solution ot a dinitronaphthol a deop-red
solution containing the potassium salt of this acid is obtained. The
free acid has not yet been obtained, but a series of salts has been
prepared, resembling the isopurpurates, but crystallizing not so well