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ANTHRAQUINONE, C14H802

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Originally appearing in Volume V02, Page 106 of the 1911 Encyclopedia Britannica.
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ANTHRAQUINONE, C14H802 , an important derivative of See also:anthracene, first prepared in x834 by A. See also:Laurent. It is prepared commercially from anthracene by stirring a sludge of anthracene and See also:water in See also:horizontal cylinders with a mixture of See also:sodium bichromate and See also:caustic soda. This suspension is then run through a conical See also:mill in See also:order to remove all grit, the cones of the mill fitting so tightly that water cannot pass through unless the mill is See also:running; the See also:speed of the mill when working is about 3000 revolutions per See also:minute. After this treatment, the mixture is run into See also:lead-lined vats and treated with sulphuric See also:acid, See also:steam is blown through the mixture in order to bring it to the See also:boil, and the anthracene is rapidly oxidized to anthraquinone. When the oxidation is See also:complete. the anthraquinone is separated in a filterpress, washed and heated to r 20° C. with commercial oil of See also:vitriol, using about 22 parts of vitriol to r of anthraquinone. It is then removed to lead-lined tanks and again washed with water and dried; the product obtained contains about 95 % of anthraquinone. It may be purified by sublimation. Various synthetic processes have been used for the preparation of anthraquinone. A. See also:Behr and W. A. v.

Dorp (Ber.,1874,7,p.578) obtained orthobenzoyl benzoic acid by See also:

heating See also:phthalic anhydride with See also:benzene in the presence of See also:aluminium chloride. This See also:compound on heating with phosphoric anhydride loses water and yields anthraquinone, See also:C6H4<CO>O ,CiH4`000Hj5~C6H4.<CO/ CsH4. It may be prepared in a similar manner by heating phthalyl chloride with benzene in the presence of aluminium chloride. Dioxy- and tetraoxy-anthraquinones are obtained when See also:meta-oxyand dimeta-dioxy-benzoic acids are heated with concentrated sulphuric acid. Anthraquinone crystallizes in yellow needles or prisms, which melt at 277° C. It is soluble in hot benzene, sublimes easily, and is very See also:stable towards oxidizing agents. On the other See also:hand, it is readily attacked by reducing agents. With See also:zinc dust in presence of caustic soda it yields the secondary See also:alcohol oxanthranol, C6H4: CO•CHOH : C6H4, with See also:tin and hydrochloric acid, the phenolic compound anthranol, C6H4: CO•C(OH): CsH4; and with hydriodic acid at r 5o C. or on See also:distillation with zinc dust, the See also:hydrocarbon anthracene, C44H10. When fused with caustic potash, it gives benzoic acid. It behaves more as a ketone than as a quinone, since with See also: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. Various sulphonic acids of anthraquinone are known, as well as oxy-derivatives, for the preparation and properties of which see See also:ALIZARIN.

End of Article: ANTHRAQUINONE, C14H802

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