Anthraquinone-2-

Anthraquinone [84-65-1] has yet to be found in nature, although some of its substitution products have been known since antiquity (alizarin, kermes, cochineal, and lac dye). Of all the quinones found naturally, those derived from anthraquinone far exceed all others. Many of these are found in molds (2). 

Anthraquinone, has been variously named 9,10-dLhydro-9,10-diketoanthracene, 9,10-dihydro-9,10-dioxoanthracene, and 

In the eadier Hterature, the 1,4,5,8 positions were known as alpha (a) and the 2,3,6,7 as beta (P). The 9,10-positions are known as meso- or ms-. Other quinones of anthracene are known, but only the 9,10-quinone is of technical importance. 

Kirk-Othmer Encyclopedia of Chemical Technology (4th Edition) 

When sublimed, anthraquinone forms a pale yeUow, crystalline material, needle-like in shape. Unlike anthracene, it exhibits no fluorescence. It melts at 286°C and boils at 379°—381°C. At much higher temperatures, decomposition occurs. Anthraquinone has only a slight solubiUty in alcohol or benzene and is best recrystallized from glacial acetic acid or high boiling solvents such as nitrobenzene or dichlorobenzene. It is very soluble in concentrated sulfuric acid. In methanol, uv absorptions of anthraquinone are at 250 nm (e = 4.98), 270 nm (4.5), and 325 nm (4.02) (4). In the it spectmm, the double aUyflc ketone absorbs at 5.95 p.m (1681 cm ), and the aromatic double bond absorbs at 6.25 p.m (1600 cm ) and 6.30 pm (1587 cm ). 

Anthraquinone. Anthraquinone an important intermediate used extensively in the dye industry can be manufactured through the oxidation of anthracene.1041,1042 Almost all anthraquinone is currently produced by oxidation with Cr03 in the liquid phase (50-100°C) with selectivity better than 90% at complete conversion. 

The selective oxidation of hydrocarbons, particularly that of alkanes, remains a challenge. It is not surprising, therefore, that the problems of oxidation processes are addressed in several books,1043-1045 reviews,1046-1057 and a journal special issue,1058 as well as in international conferences1059-1064 devoted to the topic. For the advances in chirally catalyzed oxidation processes, including asymmetric epoxidation and osmylation, Sharpless was one of the recipients of the 2001 Nobel Prize in Chemistry. 

P-Methylanthraquinone. Use 10-5 g. of p-toluyl o-benzoic add (preceding Section) and 90 g. (46 ml.) of fuming sulphuric acid (20 per cent. S03). Recrystallise the product from alcohol in the presence of a little decolourising carbon. The yield of pure (3-methylanthraquinone, m.p. 176°, is 7 - 5 g. 

Sublime a small amount of the dried anthraquinone ( 35, page 24), and crystallize a little from boiling alcohol. 

Anthraquinone sublimes at about 250° in yellow needles which melt at 273°. The yield in this preparation is 5 grams. 

Boil together for about half a minute a trace of powdered anthraquinone with a little zinc dust and 10 cc. of a solution of sodium hydroxide. Filter the solution and shake it with air. Anthraquinone is partly reduced by zinc and sodium hydroxide to a red salt of the composition  

This salt is oxidized by air to anthraquinone. The reaction is a valuable one in the identification of this substance. 

Compare the properties of anthraquinone with those of benzo-quinone. Does the former oxidize an acidified solution of potassium iodide Is it reduced by sulphurous acid  

5-Methyl-1,4-naphthoquinone (I) was obtained by the Diels-Alder addition of piperylene to / benzoquinone.n 

1-Methylanthraquinone (II) was synthesized by fusing o-(o-toluene)benzoic acid and poly-phosphoric acid and cooling the mixture with the addition of some 

1- Arylcyanomethyl-9,10-anthraquinones (II) were obtained by the interaction of the corresponding anthraquinone derivatives with phenylacetonitrile and penta-fluorophenylacetonitrile in dimethyl sulfoxide (DMSO) in the presence of a base.36 

5- and 8-Monoxy-l-aryl-9,10-anthraquinones (II) were synthesized by the condensation of corresponding halide anthraquinones with phenols.19 

Amino- and methoxy-substituted derivatives of l-acyloxy-9,10-anthraquinone 

---

Dissolves in alkaline solutions to give purple-red solutions which are precipitated as lakes by heavy metal salts. Occurs naturally as a glucoside in madder but produced synthetically by fusing anthraquinone-2-sulphonic acid with NaOH and some KCIO3. Applied to the mordanted fibre. Al(OH)3 gives a bright red lake, Cr(OH)3 a red lake, FefOH) ... 

C. A typical aromatic amine. Best prepared by the prolonged action of concentrated ammonia solution at a high temperature upon anthraquinone-l-sulphonic acid in the presence of BaClj and by reduction of the corresponding nitro compound or by amination of the chloroanthraquinone. 

Of little use commercially except as a route to anthraquinone. For this purpose it is oxidized with acid potassium dichromate solution, or better, by a catalytic air oxidation at 180-280 C, using vanadates or other metal oxide catalysts. 

It is an important dyestuffs intermediate. It condenses with chloroethanoic acid to give phenylglycine-o-carboxylic acid for the synthesis of indigo. It can be diazotized and used as a first component in azo-dyes it condenses also with chloroanthraquinones to give intermediates for anthraquinone dyes. 

It is prepared by acidifying an alkali solution of anthrone or by reduction of anthraquinone with aluminium powder and concentrated sulphuric acid. 

Reduction of anthraquinone gives dianthryl, anthrone and finally anthracene. 

It has been used as a bird repellant and is the parent compound of the anthraquinone vat dyes in which the dyeing is carried out by immersion in the reduced vat solution followed by air oxidation to the original insoluble compound. 

Anthraquinone can be brominated, chlorinated directly to the tetrachloro (I, 4, 5, 8-) stage, nitrated easily in the 1-position, but gives the 1,5-and 1,8-dinitro-derivalives on prolonged nitration the nitro groups in these compounds are easily displaced by neutral solutions of alkali sulphites yielding the corresponding sulphonic acids. Sulphonation with 20-30 % oleum gives the 2- 2,6- and 2,7-derivatives in the presence of Hg the 1- 1,5- and 1,8- derivatives are formed. 

Anthraquinone-J -sulphonic acid. Colourless leaflets, m.p. 214 C. It is used in the preparation of l-aminoanthraquinone. 

Fieser s solution An aqueous alkaline solution of sodium anthraquinone -sulphonale (silver salt) reduced with sodium dithionite, Na2S204, and used as a scrubbing solution for partially removing O2 from, e.g., N2. 

Prepared by condensing p-chlorophenol with phlhalic anhydride in sulphuric acid solution in the presence of boric acid. The chlorine atom is replaced by hydroxyl during the condensation. It can also be prepared by oxidation of anthraquinone or 1-hydroxyanthraquinone by means of sulphuric acid in the presence of mercury(ll) sulphate and boric acid. 

The above method has now been largely replaced by a newer process, in which the substance 2-ethylanthraquinone is reduced by hydrogen in presence of a catalyst to 2-ethylanthraquinol when this substance is oxidised by air, hydrogen peroxide is formed and the original anthraquinone is recovered ... 

Compounds containing olefine links may be oxidised to 1,2-diketones, as in C4H CH CHC Hs -> C HjCO-COC H. Anthracene is readily oxidised to anthraquinone, but phenanthrene is almost unaffected. 

Anthracene is oxidised by chromium trioxide, Cr04, to anthraquinone. As the reaction is carried out in solution, a solvent is required which will dissolve both the anthracene and the chromium trioxide, and at the same time be... 

Recrystallise the remaining half of the crude anthraquinone from boiling acetic acid, using animal charcoal filter the hot solution through a Buchner funnel which has been preheated by the filtration of some of the boiling solvent, as the anthraquinone crystallises rapidly as the solution cools. Cool the filtrate in cold water and then filter at the pump, drain, wash with methylated spirit and dry. Yield, 4-5 g. 

Dissolve 1 g. of anthracene in 10 ml. of glacial acetic acid and place in 50 ml. bolt head flask fitted with a reflux water-condenser. Dissolve 2 g. of chromium trioxide in 2 ml. of water and add 5 ml. of glacial acetic acid. Pour this solution down the condenser, shake the contents of the flask and boil gently for 10 minutes. Cool and pour the contents of the flask into about 20 ml. of cold water. Filter off the crude anthraquinone at the pump, wash with water, drain well and dry. Yield, 1 g. Purify by re crystallisation from glacial acetic acid or by sublimation using the semi-micro sublimation apparatus (Fig. 35, p. 62, or Fig. 50, p. 70). 

Anthraquinone is of great technical importance, as many of its derivatives form valuable dyes notable among these are the hydroxy-derivatives (alizarin, etc.)y the amino-derivatives (indanthrene, etc.) and the sulphonic acids. 

Benzoquinone, p-toluquinone, 1 2-naphthoquinone,, naphthoquinone, anthraquinone,, io-phenanthraquinone, alizarin. 

Anthraquinone and alizarin are unaffected by sulphurous acid. Phenanthraquinone is reduced in warm ethanolic solution by SO2 water to hydrophenanthraquinone, m.p. 147°. 1,2-Naphthoquinone gives the corresponding hydronaphthoquinone, m.p. 60°. Toluquinone gives toluhydroquinone, m.p. 124 . 

Anthraquinone does not liberate iodine from KI solution. 

Alizarin dissolves in aqueous NaOH solution giving a purple solu tion. Calcium hydroxide will precipitate a blue sdt from this solution. Anthraquinone is unaffected by NaOH solution. 

---