Sodium anthraquinone- -sulphonate

Sodium anthraquinone- -sulphonate ( silver salt ). Place 60 g. of fuming sulphuric acid (40-50 per cent. SOj) in a 250 or 500 ml. round-bottomed flask and add 50 g. of dry, finely-powdered anthraquinone (Section IV, 145). Fit an air condenser to the flask and heat the mixture slowly in an oil bath, with occasional shaking, so that at the end of 1 hour the temperature has reached 160°. Allow to cool and pour the warm mixture carefully into a 2 htre beaker containing 500 g. of crushed ice. Boil for about 15 minutes and filter off the unchanged anthraquinone at the pump. Neutrahse the hot filtrate with sodium hydroxide and allow to cool, when the greater part of the sodium anthraquinone- -sulphonate separates as silvery glistening plates ( silver salt ). Filter these with suction and dry upon filter paper or upon a porous plate. A second crop of crystals may be isolated by concentration of the fitrate to half the original volume. The yield is 40-45 g. 

Irradiation of sodium anthraquinone sulphonates in micelles leads to photoreduction to the corresponding radical anions, whose lifetimes are much lengthened compared with those obtained in the absence of surfactants.31 It is reported that photoreduction of anthraquinone sulphonates in basic water-alcohol solutions can lead on to desulphonation of the 9,10-dihydroxyanthracenes which are produced.32 Photoreduction of sodium l,2-naphthoquinone-4-sulphonate in water gives the 1,2-dihydroxy-compound.33 In this reaction,... 

Alizarin. Dissolve successively in 75 ml. of water 6 g. of potassium chlorate, 20 g. of sodium anthraquinone- p-sulphonate and 75 g. of sodium hydroxide. Transfer the mixture to a 500 ml. autoclave (compare Section VI,4) and heat for 20 hours at 170°. After coohng, scrape out... 

A mixture of 2 g. of potassium chlorate, 30 g. of commercial sodium hydroxide, 10 g. of finely powdered sodium /3-anthraquinone-sulphonate ( silver salt ), and 40 c.c. of water is heated for twenty hours at 170° (oil bath) in an autoclave or in an iron tube with screwed-on cap. The cooled melt is repeatedly extracted with hot water and the extracts, after being combined and filtered, are acidified while hot with excess of hydrochloric acid, which precipitates the alizarin. When the mixture has cooled the precipitate is collected at the pump, washed successively with dilute hydrochloric acid and water, and dried. 

Fig. 3.130. HPLC chromatograms of the test mixture detected by DAD (270 nm, upper lane) by APCI-MS-TIC (middle) and by ESI-MS-TIC (lower lane). Peak identification l=benzene sulphonic acid sodium salt 2=2-naphtalene sulphonic acid sodium salt 3=2-anthraquinone sulphonic acid sodium salt 4 = sulphorhodamine D sodium salt 5=crocein orange G 6=eriochrome black T 7=2,6-anthraquinone disulphonic acid disodium salt 8 = 1,5-naphtalene disulphonic acid disodium salt 9 = azophloxine 10 = 1,2-benzene disulphonic acid dipotassium salt. Reprinted with permission from G. Socher et al. [178].

Sodium anthraquinone-l-sulphonate (H2O) [107439-61-2] M 328.3. Crystd from hot water (4ml/g) after treatment with active charcoal, or from water by addition of EtOH. Dried under vacuum over CaCl2, or in an oven at 70°. Stored in the dark. 

Sodium anthraquinone-2-sulphonate (H2O) [131-08-8] M 328.3. Recrystd from MeOH [Costa and Bookfield JCSFT 7 82 991 1986]. 

This product melts at 15° C., boils at 171° C. at 4 mm. and has a density of 1 4724 at 25° C. Replacement of the sulphide by / j8 -dichlorodiethyl sulphone or sulphoxide yields respectively di-p-ethylselenolethyl sulphone9 S02(CH2.CH2.SeC2H5)2, M.pt. 72 5° C., and the corresponding sulphoxide, SO(CH2.CH2.SeC2H5)2, an oil, decomposing on distillation at 4 mm. Condensation of sodium ethyl selenide with sodium anthraquinone-1-n-butylsulphone-5-sulphonate similarly yields 5-ethylselenol-l-n-butyl-sulphone anihraquinone, which does not melt below 300° C. ... 

The sulphonation of toluene (Expt 6.37) with concentrated sulphuric acid at 100-120°C results in the formation of toluene-p-sulphonic acid as the chief product, accompanied by small amounts of the ortho and meta isomers these are easily removed by crystallisation of the sodium salt of the para isomer in the presence of sodium chloride. Sulphonation of naphthalene at about 160°C yields largely the 2-sulphonic acid (the product of thermodynamic control) (Expt 6.38) at lower temperatures (0-60 °C) the 1-sulphonic acid (the product of kinetic control) is produced almost exclusively. In both cases the product is isolated as its sodium salt. In anthraquinone the carbonyl groups deactivate the aromatic nucleus towards electrophilic attack and vigorous conditions of sulphonation are required, i.e. oleum at about 160 °C. The product is largely sodium anthraquinone-2-sulphonate (Expt 6.39). 

Occasionally in the synthesis of phenols by this route oxidation products are formed. A particular example is provided by the alkali fusion of sodium anthraquinone-2-sulphonate during which a second hydroxyl group is introduced into the 1-position, forming the dyestuff alizarin (1) (cognate preparation in Expt 6.99). In the procedure described the oxidation step is promoted by the deliberate introduction of potassium chlorate as an oxidant. 

Cognate preparation. Alizarin. Dissolve successively in 75 ml of water 6g (0.049 mol) of potassium chlorate, 20 g (0.065 mol) of sodium anthraquinone-2-sulphonate (Expt 6.39) and 75 g of sodium hydroxide. Transfer the mixture to a 500-ml autoclave (compare Section 2.17.2, p. 97) and heat for 20 hours at 170°C. After cooling, scrape out the violet-coloured mass and extract it three or four times with 100 ml portions of boiling water. Acidify the filtered extract with hydrochloric acid. When cold, filter the orange precipitate of alizarin at the pump, wash it thoroughly with cold water and dry at 100 °C. The yield of alizarin is 14 g (90%). It may be purified by recrystallisation... 

There are numerous references in the Patent Literature (72—76) to the use of anthraquinone and similar compounds as photoinitiators of polymerization or crosslinking required in the preparation of printing plates etc, although apparently little is known of the detailed reaction mechanisms. One literature report (77) described the polymerization of aqueous methyl acrylate by sodium anthraquinone-2-sulphonate in the presence of chloride ions, with a conclusion that the initiating species are chlorine atoms. 

Alizarin, the dyestuff contained in madder, is made from anthracene, another coal tar product, by the action of "sodium bichromate and sulphuric acid to form antbraquinone this is traniSformed by the action of sulphuric acid into anthraquinone sulphonic acid, the sodium salt of which when fused with soda and a little potassium chlorate yields a compound of alizarin containing sodium, from which alizarin itself is made by the action of acid. 

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